San Bruno Pipeline Blast: Another NTSB update

On Tuesday the NTSB released a short update and a few more pictures of a 28-foot-long ruptured section of the pipe involved in the San Bruno gas explosion. 

News reports picked up on two new pieces of information about pipe construction:

• While PG&E's specifications on file for the 1956 construction say that the pipe was of seamless manufacture, some of the length had welded seams; and
• While some of those seams were welded inside and out, others were welded only on the outside.

Earlier photographs indicated that some of the pipes had welded seams, like this one:
 
What appears to be a weld bead is visible as a light gray line in the shadow on the lower left. This is in a long segment.

Despite the headlines and commentaries this week it's not yet clear from the NTSB's sparse technical information whether welding methods played a part in this failure. NTSB might have been pointing out that pipeline companies could do a better job of having their filed surveys match the as-builts.

Based on the photographs and two papers released so far, I'm guessing that the fracture started in one of the short segments (called pups), or a junction between them. Pups are short lengths of pipe, typically installed so that the pipeline can make a bend. This location is at the bottom of a hill so that could explain the pups. 

The pups mentioned in the report are a little more than three feet long. In this photo they are called Short Segments 1 to 4.

My inference from the photos is that the NTSB is taking a good deal of interest in two of the pups, labeled Short Segments 1 and 2. Take a look at this photo:

The investigator is cleaning fracture faces at the junction of two cracks. One crack runs along a failed girth weld that joined Pups 1 and 2; the second is a longitudinal fracture in Pup 2. This second fracture runs down Pup 2 toward the lower right, joins another girth crack, and trails off a few inches later. It's hard to tell from the photograph whether this second crack follows a seam weld.

All catastrophic fractures have to initiate somewhere and I'm guessing that the starting point is in the foreground of the photograph above, perhaps near the investigator's left hand.

I also feel pretty confident that the segment we see in the photographs is inverted, that is, that we are seeing it upside-down compared to its original position underground. 

Note that the NTSB in its update said there is no evidence of external corrosion on the outer surfaces; it didn't dismiss internal corrosion.

Those who want to take a closer look at the photographs and updates can find them on the NTSB's docket page.

Unstoppable and the Story of CSX 8888

The movie Unstoppable will add another heartwarming holiday movie tradition, the runaway train heading for a tank farm. The opening of the movie says it was inspired by true events. As in: loosely inspired by unmanned, runaway locomotive CSX 8888, dragging 47 cars through central Ohio on the afternoon of May 15, 2001. What railfans call the story of Crazy Eights was due to a combination of errors (most of them made in haste by the engineer) that exposed a loophole in the alerter, aka dead man switch.


This particular engine was an Electromotive SD-40-2. It followed all the basic principles of diesel-electric engines used on the high line:

• They're powered by big diesel motors;
• Those diesels turn generators;
• The generators send power through heavy cables to traction motors in the sets of wheels below the main body of the locomotive;
• When he wants to slow down, the engineer has a choice of three braking systems: he can (1) apply air-operated brakes on the locomotive itself (called the independent brake); (2) apply air brakes on all the trailing cars but only if the air lines are connected (called the automatic brake); or (3) reverse the operation of the traction motors so they act as generators, which makes each motor act like a brake (called the dynamic).
• Since the reversed motors now act as generators, the energy has to go somewhere; while in theory it could be used to charge batteries hybrid-fashion, these would have to be very large so instead it's dumped to the air through giant resistance elements on the top of the locomotive. These are called braking grids. If you're standing on a bridge as a train passes under, you can see the big round openings that allow air through the grids. They look like window fans laid on their sides; the fans are to help pull the heat out.
• Because steel wheels on steel rails have low friction, trains and individual railcars can start running away when unpowered, after mass and gravity have overcome brakes and other obstacles. Runaways under power are quite rare.
• Guarding against this is the dead man switch or “alerter”, a fail-safe device to shut off engine power and apply brakes if the engineer fails to show any activity. On this model, that time span was 40 seconds … but only if it wasn't deactivated.
  

The movie had to jazz things up here, and simplify there. There wasn't a man lowered by helicopter; “Crazy Eights” didn't ram railcars or any other vehicles; the only injuries were minor, to the engineer; and it didn't almost fly off on a curve next to a tank farm. And the movie didn't explain the chain of events that set 8888 loose.

But there were many exciting aspects of the real incident that the movie drew upon: an attempt by police to use gunfire to hit the emergency shutoff (failed), an attempt to use a portable derailer (failed), and a chase from behind in which a locomotive latched on and used dynamic braking (which worked well enough, and better than shown in the movie). The train consist did include two cars with molten phenol.

While the chase was exciting, safety-lesson-wise the most interesting events all happened in Toledo's Stanley Yard, where the incident began.

Set aside the full track layout; concentrate only on three relevant tracks. Think of the capital letter “Y,” with a two-armed fork above and a stem below. The time is about 12:30 pm. As the story begins, the train is sitting in one fork of the Y, in the railyard. Because the train isn't complete as a “consist” yet, it needs to pull forward out of one arm of the fork into the stem, then come to a stop while the switch behind it is thrown; and then back up into the other arm of the fork to pick up some more cars. 

This is such a routine operation around railyards, where cars are always being shifted around, that the crews don't fasten the air hoses from the railcars to the locomotive, which would be necessary to operate the brakes on each car. (The movie shows this as an aberration, but it's a routine time-saver.) So the only way to brake this short-lived train will be to use the “independent” air brake on the locomotive. Once it's made up into a consist, the crew will make the train ready by hooking up the air hoses.


To move his train into the stem of the Y so it can be switched, the engineer throttles up. With just a few more cars necessary to clear the switch, a brakeman standing there calls the engineer on his radio and tells him to start slowing down, since the train has to stop and come back once the switch is thrown, to move into another track in the classification yard. No answer! In fact, the train gains speed to 11 mph.


The answer to this odd behavior can be found at the head of the train, a half mile away. The engineer had heard via radio that another switch in front of the engine, further along the stem of the Y, has been left in the improper position. He's moving too fast to stop short of it and he concludes that if the locomotive hits the switch as is, it's going to cause damage and delay. What to do? There's nobody up ahead he can radio to line the switch. 

The engineer decides in a flash that he will reset the controls to slow and then stop the train, but jump off before it stops, and dash ahead to reset the second switch himself. It's an odd decision for an experienced engineer, since engineers aren't permitted to jump off a moving train other than in cases of imminent collision.


His plan is to use all three braking methods to slow the train. He applies the independent brake on the locomotive. Normally the locomotive's brake shoes would be enough to stop the 3,000-ton train … but only if the engine was not producing force.


But he also tries to apply the train's automatic air-brake system and to engage the dynamic brake. These latter two actions are the immediate cause of the problem. I'll get to the reasons in a minute. Without time to check what he did, or tried to do, he jumps off the locomotive and sprints ahead, throwing the second switch with seconds to spare. He hears that the train is under power and sees that it is speeding up. So he tries to get back on board as the engine passes. But it's raining and he slips before getting aboard the engine. He is dragged a few dozen feet, then lets go. He puts out the alarm that a runaway train is heading south on the high line.


Controllers clear the path, police guard the crossings, and CSX tries to use a derailer on a siding to stop it. That fails. In the end, a chase locomotive catches up with it at Kenton, Ohio, and latches on. Using the dynamic brake, the crew slows it enough that an engineer can clamber aboard Engine 8888 and reset the controls.


The first error was that somebody left the second switch ahead of the train in the wrong position. That error forced the engineer into a hasty action that otherwise he wouldn't have taken.

The other errors were by the engineer. He inadvertently set the lever in “Run 8” position, which brought it to full power, instead of setting up the dynamic braking. It wasn't a good idea even to try to use the dynamic, since it's something to use on the high line at speed, rather than while crawling around a trainyard. Proper procedure would have been to bring down the throttle and apply the independent brake, accepting any damage to the switch as the lesser of two evils. It wasn't the engineer's problem to solve.

So why didn't the alerter, the deadman switch, automatically shut down the locomotive after just 40 seconds of inactivity by the engineer, before it even left Stanley Yard? Because the engineer had tried to apply the automatic air brakes along the length of the train. They weren't connected so they didn't work; worse, just the attempt to apply them raised the brake pipe pressure and disabled the alerter. The reason for this loophole is that engineers sometimes have to set the brakes and get off a locomotive after it stops, and they want to leave it running rather than have it shut off automatically.

With power in Run 8, the only force holding back the locomotive was the locomotive's independent brakes. Those brakes were of little effect against a full power setting, and even less effective after they burned off entirely.

Snowplows and Snowhogs: Getting to know the Avalanche Effect

 Digging through snowplow-created berms during this weekend's storm: I sent Son #3 to scale the ridge line with a shovel. He on the street, me on the driveway, we attacked it from both sides. First we made a hole and shook hands like sandhogs working on a tunnel from both ends, then went at it with a will until the hole was a valley and finally a gap big enough to drive a car through. Wished for a tunnel-boring machine.


Those living south of the snowplow line may be surprised to hear that snow gently falling on the ground is not the same as snow that has been pummeled by a snowplow blade or, even more, transformed by a slab avalanche.


This phenomenon is rarely depicted in action movies. I suppose it's because the screenwriters haven't been close to an avalanche, nor read much about them.


Slab avalanches leave anyone alive trapped in icy debris that is most impressively dense and hard. This set-up happens instantly, as the friction-heated snow refreezes. Here's an illustration: a hiker whose lower leg is covered by the fringe runout of a slab avalanche will not be able to get her foot loose without literally chopping the ice away. The consistency is something like cured, low-grade Plaster of Paris; not quite as tough as concrete, but not something she can gouge with her hands. Without a metal shovel or better yet an ice axe close to hand, she'll be lucky to get loose, boots or not. Here's an explanation from the Utah Avalanche Center, including a narrative of what it feels like to be inside one and survive.


Which leads me to a book I highly recommend for outdoorspeople: Ian Stark's Last Breath: The Limits of Adventure. It's grim but excellent reading, and goes far to strip away dangerous and foolish notions about the course of medical emergencies in the wilderness.


Each of the eleven chapters is a fictional narrative, with all events grounded in medical fact and relevant physics (as in, the physics of snow and debris in an avalanche). Some of the fictional characters survive; some don't, so there's an element of suspense in each tale. I thought I knew about dehydration until I read Stark's last chapter, "In a Land Beyond the Shade."


Rather than leave readers with bad feelings about snow, here's a picture from the storm: a pretty little cornice that formed under the eaves of our house, changing by the hour as a brisk wind carved here, and added there.

Thermobaric Warheads on the Rise: North Korea and fuel-air explosives

Just what were the North Koreans firing at Yeonpyeong Island, and from what artillery? It's likely that some or all of the fire was from their variant of Russia's BM-21 Grad MLR, short for "multiple rocket launcher" system. These are angle-adjustable banks of launching tubes on a rotating turntable; all this bolted to the back of a flatbed truck. The Grad and its knockoffs are highly mobile and quick to set up for firing; while limited in accuracy, they can launch a fearsome barrage of 40 warheads in just a few minutes, striking targets more than 20 miles away, depending on the model. Then the crew either slaps on a reload pack with 40 more rockets, or if counter-battery fire is on the way, hits the road and hunts shelter.


Allegedly the North Koreans rehearsed the attack to time their fire (which originated from multiple locations) in such a way that the projectiles struck the island at about the same time. In military terms time-on-target coordination is an effective anti-personnel tactic since troops (and civilians, here) don't have time to seek shelter.


Each Grad rocket is about ten feet long including the propellant section, and 122 mm in diameter, or a little more than five inches across. That makes for a big warhead, holding about fifty pounds of payload.


According to an article in the Daily Yomiuri, dud rounds indicate that the warheads held a powerfully engineered explosive called a thermobaric weapon; aka fuel air explosive. ("Thermo" stands for heat, "baric" for pressure.) While engineering a fuel-air explosion from a fast-moving warhead is not easy, thermobaric rounds can be very effective in military terms, and now come in sizes large and small. A unit of Marines reported in 2003 that a relatively small 40mm thermobaric grenade blew apart a single-story building. Users of the rocket propelled grenade launcher called the RPG-7 can choose from a thermobaric round called the TBG-7V.


The Germans may have experimented with thermobaric explosives in World War II and the U.S. used them against them in Vietnam, such as to clear helicopter landing zones. While still not widely used in wartime (so far) there's nothing secret about the physics of thermobaric explosions, which lie behind every house blown apart in a natural gas explosion, and every factory or grain mill wiped out by a dust explosion. Following somebody's unwise decision in February 2010 to purge pipes at the brand-new Kleen Energy Energy Systems combined-cycle power plant with natural gas, a fuel-air explosion demolished that 620-MWe plant before it even started up.


Some experts regard thermobaric explosives as several times more powerful (pound for pound) than conventional high explosives like Comp B; perhaps up to six times as powerful. One reason: because thermobarics draw their oxygen from the air; they don't have to carry an oxidizer in the warhead, so all the filler can be given over to energetics like volatile liquid fuels and aluminum particles. So thermobarics aren't going to work underwater, in space, or at very high altitudes. To see how conventional explosives are burdened with oxygen, take a look at the RDX molecule diagrammed here.


Characteristic of the thermobaric warhead in action, when viewed in slow motion, is the double explosion. The first charge disperses a superheated cloud of fuel so that it can mix with air; the second and much larger explosion that follows is the fuel-air blast. Here's a film of a big thermobaric bomb being tested.


If Country A wants to attack Country B's vast tunnel complex, count on liberal use of thermobaric warheads after armor-piercing rounds open up the portal doors. The effect of a fuel-air explosion, which is plenty devastating in the open, is greatly magnified in confined spaces if the proper fuel-air mix can be achieved.

Helicopters and High-Rise Fires: McDonnell Douglas's "rescue angel"

Here's the second part of my post on helicopters at high-rise fires. This focuses on McDonnell-Douglas's flying rescue machine. The material is adapted from my book The God Machine on the social history of helicopters.

By 1976 it was clear that helicopters responding to high-rise fires like Andraus and Joelma were having problems with unruly crowds and smoke obscuring the roof. 

One solution, it seemed to fire chiefs at the time, was to keep the rescue helicopter high above, away from fires where pilots might lose their orientation, or machines might sustain damage from heat or suffer loss of power. In 1976 the chiefs of two dozen American fire departments wrote to McDonnell Douglas Corporation and described the problem. 

The aerospace contractor came back with plans for the Suspended Maneuvering System and went on to build a prototype. The SMS was a supercharged, sixteen-passenger rescue basket designed to hang from a large helicopter at the end of a 500-foot-long steel cable. 

The SMS had a gasoline engine and adjustable air-thruster nozzles so the operator could move the basket from side to side at the end of that tether, allowing it some horizontal freedom of movement when alongside a tall structure or above a flooding river. It had a little catwalk that could be lowered to bridge the SMS and a window.

The SMS was working in prototype by 1978. Here's a link to a Pop Mechanics profile about how MD's "angel" did in the early tests. Despite their early enthusiasm, though, fire departments dropped all plans to buy them. The chief obstacle was not the rescue device itself, which worked well in tests, but the logistical demands it placed on a fire department compared to the rarity of its use. 

Any department that would be depending on the SMS would have to arrange for fast response by a big twin-engine helicopter comparable to the Sikorsky H-60 Black Hawk. That's because of the weight to be carried and the need for extremely high reliability whenever people are being hauled around at the end of a cable hooked to the belly of a helicopter. (A hair-raising subject, and one for a later post.)

Also weighing against deployment of the SMS was a scarcity of high-rise fires after the early 1980s. The frequency plummeted after big cities began requiring sprinkler systems in skyscrapers, a move spurred by the disastrous conflagrations of the Seventies. 

Sprinklers and other fire-minded measures worked so well in stopping fires before they caught that if a fire chief had authorized an SMS unit in 1980 he could have worked another three decades and retired without seeing the SMS squad go into action, even once, at a high rise fire in his city. 

Only one department, the Los Angeles Fire Department, actually readied the SMS for action. That deployment lasted less than a year. I talked to a firefighter who participated in the effort, and he said it performed much as advertised. Here's a link to an image of the SMS as displayed in the LAFD's fire museum.

Would an SMS have been of any use at the World Trade Center that morning of September 11? I believe so ... After all, the SMS was designed specifically for getting people off of high-rises on fire -- including through the windows where the roof was untenable or unreachable. Still and all, the very short time span available would have been a problem. Everything about the mobilization would have had to operate without delay or error, with all forces from the Air National Guard to the NYPD's Aviation Unit to the FDNY acting as one.

Emerging reports about reckless practices behind the recent Shanghai high-rise apartment fire (death toll now up to 58) indicate that other high-rises there are at risk until if and when safety practices are cleaned up. So that city's FD might want to look into setting up an SMS unit; for one thing, helicopters are more reliable now and have better auto-hovering controls. It could be a lot better than nothing!
  

The Ring: Some Background

As I mentioned in an earlier post on cloudspotting, I've been snapping cloud pictures with digital cameras since mid 2008. It's a hobby, like bird watching. The catch adds up to many thousands of pictures in all kinds of weather, mostly in the US. With so much time spent looking out and up, sometimes I come across striking visual effects. They don't come along often, but add zest to the hunt.

This post is to give some context to one of those visual outliers, since I'll be talking briefly about Photo No. 147 tonight with host Ian Punnett at the top of Coast to Coast AM.

Some background: this spring I was getting ready for the summer cloud season, going back through the previous year's crop of cloud pictures to organize them and dispose of unneeded ones; it's like cleaning the electronic attic. That's when an oddity in one image caught my eye; the photo was one out of a series of snaps taken on a weekend afternoon in mid-May 2009. I didn't notice anything special when taking the pictures that day. It's one of those cameras with no viewfinder, just a screen on the back, so in daylight it's very hard to see what the camera is capturing. I was just snapping away because I liked the look of an airliner contrail alongside a set of cool clouds.

Here's the camera I used, of garden-variety:

Here's a portion of the photo in question (No. 147), which I've watermarked for copyright purposes, along with the enlargement below. The anomaly in question is a faint blue oblong in the lower left of the photo.

After enlargement and some added contrast, it looks like this:

It doesn't look like a flying object to me, somewhat more like a ring of plasma, but that doesn't help much either.


Whatever it was, it was fleeting. I had taken a string of pictures in the same general span of sky over a fifteen-minute interval with this camera, and the Ring doesn't show up in any of the others.

In particular, the immediately preceding photo, No. 146, was taken less than a minute before, probably less than thirty seconds before. No. 146 has the same clouds and a slightly shorter jet contrail, but no Ring.

I don't have any great insight about this; I just happened to be outside with a camera; but three things about Photo No. 147 pique my interest. First (and supporting the idea that this was a ring viewed at an oblique angle) is the fact that the "ends" of the ring on the left and right are brighter than other parts of the ring. Look in particular at the tip on the right, how bright it is. This would be the case if looking obliquely at a ring of plasma; the ends would be somewhat overlapped and therefore brighter. Second, there is some kind of central core inside the ring. Third (and this is barely visible until the contrast is raised), there appears to be a faint, bluish arc on the lower left. What the heck is that?

I checked with a few contacts in the world of physics, and they offered no opinion other than the ring might be a camera glitch or a lens flare. I'm no JPEG expert so for all I know, digital cameras produce such glitches randomly. This camera hasn't done so before or since, but maybe it hiccuped that time. 

But I'm pretty sure the ring is not a lens flare given the direction the camera was pointing: north or northeast. It takes a brilliant light to make a lens flare and in Minnesota in May, the sun is nowhere near the field of view of a camera that's pointed north at mid-day. Also, lens flares I've seen don't look like this. 

Date: Allowing for a mistake I made when setting up the camera clock upon purchase (for example, not changing AM to PM), I'm reasonably sure that I took Photo No. 147 on the early afternoon of Saturday, May 16, 2009. Location was the Twin Cities of Minnesota, looking north or northeast.

I'm hoping a high-energy physicist might have a look. In the meantime the only half-baked hypothesis I can offer is that it's a picture of something very distant exploding in the very high atmosphere, and the shock waves glowed so brightly they overcame the brightness of the sky at mid-day. But when comets come in and blow up there's a debris trail, and none is visible here, so my proposition has its own shortcomings.

If some kind of distant large explosion in the high atmosphere did occur and if it was within view of sensors aboard Defense Support Program reconnaissance satellites, it might have been recorded. In addition to looking down for incandescent ICBM booster plumes, DSP satellites allegedly have, over the years, detected rather large breakups of high-velocity objects in the high atmosphere. I have read that at least one was in the multi-kiloton yield. But as of now all such sensor information is classified so I can't check my hypothesis.

That's it for now; just wanted to add a little extra context for Coast to Coast AM listeners. Thanks for tuning in!

High-Rise Fires and Helicopter Rescue

A fire that engulfed a 28-story apartment in the Jing'an District of Shanghai early today appears under control, but 42 people died and over one hundred were injured. 

Initial reports indicate that some residents made it onto the roof and three helicopter crews were orbiting in hopes they could pull people off, but few if any people made it off the roof in helos due to smoke that blocked the way.

After 9/11, the mere mention of helicopter roof-rescue brought down criticism from the Fire Department of New York (FDNY), which under operating rules put into effect after the 1993 WTC bombing (and controversial use of helicopters there) would have to approve and supervise such any such effort by the NYPD's aviation unit.

Does it ever work? Yes, sometimes. Rescue helicopters have participated at more than two dozen high-rise rescues worldwide since 1963. Each of these rescues was unique, and most proceeded under difficult circumstances. Not all went as intended, but helicopters did pluck 1,200 people from roofs, ledges, and balconies.

Two of the earliest and most spectacular fires with elements of helo rescue happened in downtown Sao Paulo, Brazil, in 1972 and 1974. The first to burn was the 330-foot-high Andraus Building, a concrete-framed structure that held offices and a department store. The fire began in a pile of combustibles stored near the fourth floor and went up via the exterior walls, touching off furnishings with heat radiated through the windows as it climbed. Crowds gathered on the street, blocking fire apparatus, to watch. At its peak the wall of flame was 350 feet high, burning with the fury of an oil well fire. 

Three hundred occupants climbed the stairs to the rooftop heliport (coincidentally, the first of many heliports built in Sao Paulo, today the world's most helicopter-friendly city). But after they reached comparative safety, someone in that group went back and blocked the steel door from opening, apparently fearing that those already on the roof would run out of foot room.

Problem: there were two hundred more occupants still in the stairwell, and they jammed against the obstruction. Whether or not those below could be called in a state of “panic” (a subject for another post) they were very upset and pushed hard. They couldn't imagine why a flow up the stairs had stopped all of a sudden.

Help was on the way. A helicopter with firefighters approached, then banked away when the crowd charged it. But the helicopter came back and hovered out of reach to drop off firefighters, who quickly took control of the crowd. This allowed helicopters to land safely. 

Here's my point: The helicopters’ biggest contribution toward survival at the world-class disaster at Andraus that day was not getting people off the roof, but getting firefighters to the roof so they could break open the stairwell door. This action certainly prevented many dozens of people on the stairs from being crushed or asphyxiated by the upward pressure. As it was, some in the stairwell had broken bones or lay unconscious from smoke inhalation when help arrived. Survival was a very close thing. 

In the end sixteen people died at Andraus, but the toll would have been much higher had the rooftop doorway remained blocked.

Sao Paulo suffered another skyscraper fire two years later, at the Joelma Building, and helicopters also fluttered to that scene. But the rooftop area available to helicopters was so small, and the fire and smoke so intense, that 90 people died before the aircraft could move in. Some survivors told investigators afterward that they had remembered how helicopters had lifted people off the Andraus roof two years earlier and said that this memory persuaded them to go up the stairs instead of down, because they assumed a similar rescue would be possible. Such false hopes are one reason why the FDNY has been, and remains, very skeptical about relying on helicopters to pull people off high rises.

High-rise emergencies continued worldwide after the twin fires at Sao Paulo, each offering unique lessons in high-angle rescue. A 1980 fire at the 26-story MGM Grand Hotel in Las Vegas prompted the biggest gathering of helicopters at any high-rise emergency, before or since. Here's the NFPA write-up. Police helicopter pilots were the first to see the smoke and sent out a radio alert. Thirty public and private helicopters mobilized to move 300 people from the roof. 

Coincidentally and remarkably, Air Force rescue helicopters and crews were close at hand, having staged at nearby Nellis Air Force Base for an exercise. Fearing that the roof deck was about to catch fire, the pilots organized their ships into a racetrack pattern: approaching from the east side, picking up hotel guests on the roof, departing on the west, then dropping people off in a parking lot. Some who waved for help were on balconies well below the roof level, which ordinarily seem to be out of reach for helicopters; but rescues proceeded even at that difficult location after a flight engineer lowered himself on a “jungle penetrator” seat at the end of a cable, and tossed a rope to those on the balconies. The hotel guests then pulled the engineer to their balcony and, one by one, joined the engineer on the rescue seat. One volunteer pilot was Mel Larson, then a vice president at Circus Circus Casino and owner of a helicopter charter service. I interviewed him later.

“It was not orderly,” Larson told me about his first view of the roof, where people were trying to grab hold of the landing skids as helicopters departed. “It was panicky. We had to have police to get control. ” At one point a police officer drew his gun to make his point. Eighty-four people died at the MGM Grand, but none of the fatalities happened on the roof. (For years afterward, and at his suggestion, the management of Circus Circus cached evacuation equipment on the roof in case of such an emergency.)

One solution to unruly crowds and smoke obscuring the roof, it seemed to fire chiefs at the time, was to keep the rescue helicopter high above fire and smoke where pilots might lose their orientation, sustain aircraft damage from the heat plumes, or suffer loss of power. And rescue pilots have assured me that power loss -- even flame-outs -- due to oxygen starvation has happened. 

McDonnell Douglas took the fire chiefs' suggestions and created a sort of steerable, aerial lifeboat to be hung from a line under a helicopter. It was called the Suspended Maneuvering System. The SMS was a device of amazing abilities but was never put into regular use. A subject for a later post.

Qantas Flight 32: A reminder that turbofan engines still explode

Offering a few elaborations on the catastrophic engine failure on board Qantas Flight 32 last week, over Batam Island, Indonesia. The aircraft landed at Singapore's Changi Airport without injury to crew or PAX, but it could have been disastrous.

The engine in question (one of four mounted on the aircraft) is the Trent 972 model built by Rolls-Royce. It's a model specific to Qantas A380. Here's a link to a Rolls-Royce brochure on the Trent 900 family, with a helpful cutaway diagram.

This was the first such failure in the Trent 900 family. (An engine in the Trent 1000 family broke up in August while being tested, but I don't count that event, because testing is supposed to be rigorous and probe for problems).

The Australian Transportation Safety Board has focused on a breakup of a geared disk. The ATSB asking Batam Islanders to contact authorities if they come across a disk fragment as shown in this article at FlightGlobal.com.

The most alarming run of uncontained engine failures occurred in the late 1990s, mostly among one variant of General Electric's widely-used CF6 engine, which was exploding at an average of four times a year. Failures in later models of CF6 models remain a concern. But to be fair, the CF6 is an extremely popular engine so there are a lot of them.

A common pattern is for an uncontained breakup to happen at full power, during the takeoff run. Full power is when the disks experience the highest stress, rotating thousands of times per minute.

But there have been dozens of engine breakups in flight, as on QF32. The most famous was United Flight 232, which led to a crash-landing at Sioux City, Iowa, in 1989. The tail engine on this DC-10 exploded at altitude and its fragments cut all hydraulic lines to the control surfaces.The crew gained enough marginal control over the aircraft, using asymmetric engine thrust, to bring it down and save most of the people on board.

This reminded disaster historians of how Capt. Bryce McCormick innovated that technique 17 years earlier to bring his American Airlines DC-10 down safely to Detroit's airport, using just the engine thrust, after a cargo-door blowout over Windsor, Ontario, destroyed his ability to use the control surfaces. McCormick's plane didn't crash, it didn't end with any fatalities, and it took to the air again after repairs. See Chapter 5 of Inviting Disaster for how McCormick pulled it off.

McCormick's feat still stands as a landmark in crew emergency preparation and is one of only two airliner cases I know in which such a catastrophic loss of flight controls ended in a controlled landing with no fatalities. (The other was a DHL cargo flight in 2003 that landed safely at Baghdad after being hit by a missile that caused horrendous damage to the A300's wing and chopped the hydraulic lines). McCormick had the keen foresight, two months before the near-crash in June 1972, to train himself in a simulator on how to fly the DC-10 using only the engines. It had been his initiative alone; there was no formal curriculum on such a thing.

So that's one risk to safety, an uncontained failure severing essential controls. Another theoretical risk, which is extremely small given protective measures in modern aircraft, is that shrapnel will injure passengers in seats that happen to be in line with the shrapnel zone.

I believe the more significant risk is that an engine explosion early in the takeoff run will puncture a fuel tank and cause a fire around that wing, after the crew aborts and comes to a hard stop. This happened on a Boeing 737 after an aborted takeoff at Manchester, England. The cause of the fuel leak from a wing tank was catastrophic failure of the combustion-can casing.

But most uncontained engine failures don't cause any injuries at all and they're so exceedingly rare I wouldn't let it affect my travel plans. Major-carrier scheduled flights are much safer than driving, mile for mile. And how else is one to vault the ocean?
 
But this advice to passengers:

• If there is any sign of a sustained fire when the aircraft is on the ground report it to a flight attendant. The flight crew's view to the rear is very poor, and engine instruments sometimes lie or are misunderstood. There was the case with a British Midlands 737 in flight where the left-hand engine started tearing itself to pieces; while passengers on the left saw it happen the information didn't get to the front of the plane. The flight crew in a series of misunderstandings and missed signals concluded the problem was the engine on the right side. So they shut down the single remaining good engine instead of the faulty one on the left. When the left engine finally went to pieces on the descent there was no time for a restart and the plane crashed short of the runway at Kegworth, England. Point being: accurate, timely communication of critical information from clear-headed witnesses to decision makers can be a real life saver!
• Make sure you are familiar with the exit doors nearest to you and how to open them, say, in case the exit-row passengers haven't been paying attention. For example, sometimes removable over-wing doors become a problem if passengers behind you are pressing forward and denying you the space you need to get the door out of the way.
• Put your shoes on but leave the hand luggage behind, including laptops, briefcases, and wheelie bags. If the cabin starts filling with smoke (it will rise to the ceiling and be very visible), you are in an extremely marginal situation so saving the luggage should not be on your list of concerns. Passengers and crew will have to work closely and cooperatively to get everyone out.

Patterns in AQ-LeT Gun-team Attacks

Last month's attack by a three-man gun team on the Chechen Parliament in Grozny, and the attack earlier this week on Our Lady of Salvation Church in Baghdad, have many features in common with the Parliament House attack in India in December 2001. The principal movers at this time are Al Qaeda affiliates and Lashkar-e-Taiba (LeT).

It's important to maintain basic citizen awareness of this very dangerous tactic, which poses a real threat even though the coordinated gun-team attack has not materialized recently in the West. While a gun-team attack in a major Western city would be up against a fast and capable security response, attackers tend to hold a tactical advantage in the early moments. The best response is to stop these before the shooting starts, and a vigilant citizenry may well help alert the police to precursor events, such as hostile reconnaissance or cache preparation. I understand that now the press is zeroed in on the attempted package-bomb attack last week on cargo airliners, but I recommend that the gun-team attack move up in the public's awareness.

I checked Google News and press coverage of the package bombs is a great deal more intense than coverage of the gun-team attack on Sunday that killed 52 at Our Lady of Salvation in Baghdad. And there was even less press coverage of the October gun-team attack in Grozny.

These common features of a gun-team attack are a squad or squads who move quickly from target to target; who are trying to get past guards and into a closed area packed with people; and who act in such a way to cause maximum havoc and maximum publicity.

If the attack aims for a hostage standoff -- and most gun-team attacks do, as a means to stretch out the timeline -- there will certainly be attempts to use media  for publicity. Note that during the church attack, the gunmen tried to use Al-Baghdadiya television as an outlet for demands, until the government cut the transmitter. Extended attacks also see the gun teams carrying GPS units, satellite phones, and backpacks with ammunition, explosives, and concentrated food. There is some evidence of pre-positioned caches with additional munitions.

Gun teams typically rely on standard assault weapons (the AK-47 and a Chinese copy called the Type 56 have been common), semi-automatic handguns, grenades, and some form of suicide bomb. Lately the equipment has included cellphones linked to a VoIP address to make the controllers hard to trace.

I use the term “gun-team attack” because of the defining characteristic: one or more fast-moving assault teams relying mostly on firearms and other light weapons to attack multiple targets in a city with economic and cultural significance. This is to distinguish it from three other main types of historical terror attacks (mass hostage-taking attacks that are mostly static; assassinations; and explosive attacks on crowded buildings and mass-transit facilities).

Usually a gun team is two to four in size. Some attacks involved multiple gun teams, as in Mumbai 2008. The attack at Mumbai started out as five teams, two of which joined up on the sixth floor of the Taj Hotel (which recently reopened after two years of repairs and security upgrades). The reason for the rendezvous on the sixth floor likely was a hotel room that had been rented and stocked with a cache of weapons and supplies. (A cache was also part of preparations for the mass-hostage event at a school in Beslan, North Ossetia.)

Gun teams are not new. They were among the first in the modern terror tactics – see the 1972 Lod Airport attack by Japanese Red Army members who sympathized with the PFLP.

Three well-documented cases revealing gun-team tactics against soft targets are:

• Lashkar-e-Taiba (LeT): “Parliament House” attack, December 2001
• Al Qaeda (AQ): Attack on the Oasis executive compound, Al Khobar, Saudi Arabia, May 2004
• LeT: Attack on multiple targets in downtown Mumbai, November 2008

In general, a major gun-team attack like Mumbai 2008 develops in ten stages:

1. Hostile reconnaissance of the target, possibly a year or more ahead: these operatives walk around with cameras and GPS devices to note hallways and doors. A list of ~200 principal targets around the world is already known from interrogations, ELINT, and captured computer files and we can hope the security people are watching the cameras for such behavior. 
2. Gun-team training in a remote location, currently Pakistan but Yemen and Somalia are also likely. Gun teams receive intensive training based on such reconnaissance. They spend much time on tactical shooting and physical endurance. These men are young and highly motivated until captured, at which point their resistance seems to melt.
3. Acquisition of special gear, like satellite phones, IEDs, SIM cards for cellphones, and inflatable boats. The attackers at Grozny were in touch with a handler by cellphone, as were the attackers in Mumbai. Given this pattern it's likely that authorities in major cities are now ready to shut down local cellphone networks.
4. Sometimes, staging caches of supplies inside the primary targets.
5. Final selection of gun teams at the training camp. The organizers try to screen out those who will balk at indiscriminate killing.
6. Arrival in target city. Teams split up and try to reach the primary targets without detection. The idea is to penetrate deeply into the target without using most of the ammunition, leaving most of it for use in a confined space crowded with targets. This didn't work at Parliament House but only because the Indian Vice President's motorcade happened to be blocking the narrow gate the attackers were trying to use.
7. First stage of attack: “Large-space attacks”. Timed for high traffic hours in a crowded public place like a mall, tourist destination, or train station. Teams throw grenades and fire automatic weapons at anyone in sight, killing as many as they can and then running off. If police return fire the gun teams will retreat and move to a softer target. If the space is large enough and has enough exits this stage of shooting might go on for an hour, and so the death toll is high. The gun teams are hard to stop unless police can arrive very quickly.
8. Second stage of attack, “Small-space attacks”: A gun team leaves the first location and moves to someplace more confined. Most likely is a restaurant or club near a five-star hotel. They continue shooting there. They begin setting fires and taking hostages before they move to the final destination. If they don't break off the attack and try to escape, this leads to:
9. The third stage of attack, “hostage-holding”: Hostages are brought to a defensible location, likely to be upper floors of a hotel or apartment building. More fires are set, and boobytraps may be laid. At this point the teams may join up with each other and try to establish regular communication with leaders in a remote location. The organizers want to prolong the event as long as possible, adding fires and explosions. Often this involves checking identification and making a big show of releasing Muslims.
10. Fourth stage of attack, “martyrdom”: Die as martyrs in a firefight with police or in a bomb explosion.

The main goals of a gun team attack like Mumbai are to promote the organization as an effective fighting force, attract recruits, and polarize Muslim and non-Muslim societies. Since all these goals depend on receiving 24/7 worldwide publicity, organizers try for attacks in internationally-known locations, that are sustained over many hours, and that have visual elements suited for TV. Mumbai 2008 achieved all of these. Indications are that AQ affiliates and LeT have decided that classic suicide bombings are not able to achieve the high publicity profile that only a sustained drama can provide, though IEDs are likely to be in the list of weapons.

Why don't these attacks happen more often? Obviously there is a lot of preparation and planning but I think the main reason is that the organizers go to a great deal of extra effort to avoid failed missions. Mission failure and particularly capture of their fighters alive strike at the heart of the belief system. If the recruit base starts to think that such attacks aren't working, it's harder to get would-be martyrs to come forward. 

A large-scale collapse of martyr-willingness happened halfway through the Iran-Iraq War of 1980-1988. There is good evidence that the human wave attacks of Basij early in the war couldn't be sustained politically among the Iranian population because human waves just weren't working against massed Iraqi artillery, tanks, and Mi-24 gunships.

So it's important to capture enemy fighters alive during these events, then gather information through patient, humane interrogation. No Abu-Ghraib heavy-handed tactics are necessary. Most young fighters agree to talk, once separated from their handlers. Additional evidence that their resolve is weaker than commonly thought comes from cellphone calls recorded between the attackers in Mumbai and their controllers. Despite LeT's screening efforts, some of the attackers once on the ground repeatedly balked at controllers' orders to carry through with the carnage expected of them, during the hostage-taking stage.

Meatballs with a Chance of Cloudspotting

While as a dad I enjoyed the art and humor in the picture book Cloudy With a Chance of Meatballs, I wasn't interested in going to the recent movie. But I had to watch some of it anyway, as a silent film, since it showed on the airliner during a flight back from Japan this summer.

The blog title refers to my distracted style of eating, say, if we are having Italian. If the sky-light is favorable and the clouds are mobilized, I'll excuse myself several times to peek out the window, sometimes to run outside with a camera. My urge toward cloudspotting is in its third year and shows no sign of abating. It began with collecting digital time-lapse movies of cloud formation.

Many cloudspotters dislike contrails because they can make the sky look like a poorly-scrubbed blackboard. Atmospheric studies during the airline-banned three-day period immediately after the 9-11 attacks did show a distinct difference in cloud formation over the continental US.

But they can have a beauty of their own. Here's a garden-variety contrail:

Sometimes contrails linger and spread out.

Next is a distrail, meaning where a jet cuts a slot. I've only seen this in low- and mid-level clouds. The reason that there are two parallel slots is that sequential jets on their landing approach were following the same track, but the cloud here, which looks like a stratus nebulosus, was moving from south to north so each jet cut a new slot.

If the air is just right, high-level contrails can create some spectacular loops and whorls as the contrails are caught in the wingtip vortices shed by wings and the tail empennage. I see these less than a dozen days a year. In my limited experience it's most likely early in the morning, when the stratosphere is extremely calm. It may more likely during the turnaround, a brief time of year when there is low windshear in the stratosphere - that's when NASA launches its ultra-high-altitude scientific balloons. (Here's a link to an article I wrote for Smithsonian Magazine about that facility's work.)

At any rate the air up there has to be near saturation or else the moisture (which is always in the form of ice crystals) will sublimate before something interesting happens. Here are two contrail-curiosity photos, the first a smoke-ring of sorts I caught a month ago:

Here's a string of contrail beads, from two winters ago, low on the horizon at sunrise. Like nearly all the coolest cloud displays, these last less than five minutes, so if you want to catch them keep a camera close to hand.

Papier Mache + Halloween = Dinosaur Overpopulation

What do bloggers do when not huddled over a keyboard? On Halloween, they could be operating dinosaurs.

This year will be the 20th anniversary of our family's dinosaur display. The star of the show has always been Bronte', a dinosaur neck about fourteen feet long that cantilevers out from an upper window. To a kid, this suggests that the rest of him is inside the house, probably sitting in front of a fireplace. His neck is a Kelly green. In conjunction with a four-way swivel and a hundred-pound counterweight, I can have him raise up and eat leaves off the maple tree, look from side to side, and lean down to greet the kiddies. There's a speaker in his throat connected to a microphone at my side, and his jaw moves when I yank on a wire. There's nothing high tech in the rig; his eyes are painted wide open in a gesture of perpetual surprise.

After two decades of manhandling, storage among the rafters, and snowy evenings, Bronte's paper-mache skin has a well-aged, wrinkly look. When it's snowy, we add a gray scarf. One year a steady drizzle weakened the papier mache (which acts like the fuselage of a monocoque airplane) and his neck broke in half. We finished out the evening by propping him on a ladder. We patched him the following year, adding to his air of longevity.

We began playing with papier while in Texas. Construction of a living fossil starts with a skeleton built up from joists, bolts, and two by fours. Then I give the bones a body with more boards, dowel rods, and stiff wire. I add a skin of chicken wire and strips of gluey newspaper.

Tip: if there are any special effects, install those _before_ installing the skin. Cutting a hole in chicken wire and thrusting one's hands in to for elective surgery is a scarifying experience.

Because such creatures don't look particularly big at the early stages, it's easy to overdo it. Our first attempt was a papier mache claw with dripping red fingernails. Because I wanted it to emerge out of one window and extend to the front porch, it measured the size of a small car upon completion. That's impossible to store from year to year. After moving to Minnesota, we set a size limit of 16 feet in the longest dimension.

... But not a population limit. At its Jurassic peak, besides Bronte', our house had a smoking volcano about five feet high, a cave covering the front door, a large T-Rex in one window, a smaller long-neck dino called Bronte' Junior in another window, a Stegosaurus, and a pterosaur hanging from the entrance.

We found the volcano among the most labor-intensive of the displays, because it had no internal structure but rather was a series of flats that leaned on a central foundation, something like a tepee. We built it in four sections so the flats could be stored during the off-season on racks in the garage above the cars.

Volcanoes are pallid things without smoke. We tried dry ice and various fog and smoke generators, but nothing worked quite so well as a stockpile of highway hazard flares, because they generated a lurid red smoke.  This remained popular until the final year, when one of the magnesium flares melted through the steel bucket we used for a firebox, and came rather close to burning down our volcano. It would have been hard to explain to the firefighters.

Around 2000 the menagerie was cramping our style, at least in the garage, attic, and basement. The great extinction began. After I dropped off Bronte' Junior at the landfill, I looked back in the rearview mirror to see that one landfill guy was holding it up and using it like a big puppet to talk to his co-worker. So I like to think Junior's still in action somewhere.

So now we are one: Bronte' Senior. While running the controls upstairs, I depend on a relative to shill for me in the front yard to listen and call out the kids' first names, so I can strike up a conversation. It's dark on the lawn and there are red and yellow spotlights shining in my eyes between the blackout curtains. Without help I can't tell if the kid in question is dressed as a pirate or a turtle or a Toy Story Army Man.

Yes, our dinosaur is a big fraud, only a paper moon, but otherwise worldly-wise teenagers of the neighborhood still drop by to say hello.

Truman Soap Co: Not with this Ex-President

In this post about the Truman Committee I had mentioned a family connection to Harry Truman; he was the nephew of ex-Confederate guerrilla James J. Chiles, on my father's side.

While in DC last week I was visiting at 4701 Connecticut Ave. and in the second-floor hallway was surprised to see a plaque on a door noting that the apartment (now a condo) had been the Washington home of Truman as a US Senator and for 82 days as vice president, up until FDR's death in April 1945.

The units are roomy and well laid out, with many nice architectural details.

After Truman left the White House in 1953, he couldn't have returned to this apartment. The reason is that he couldn't have afforded it, having no income other than a $112 monthly Army pension. At the time there were no pensions for ex-presidents, and no expense account for office space or staff or a library or anything else. It must have been sobering for him to contemplate James Monroe, who had to move in with his daughter to get by, and Thomas Jefferson, who died in debt.

Still, unlike all recent ex-presidents -- some more than others -- Truman declined to trade honor for cash. He turned down lucrative offers including a ceremonial position with a Florida land company for $100,000 per year, a free car, and cash for selling his name for use by the "Harry S. Truman Soap Company." Evidence of the soap offer can be seen at the Truman Library.

Said Truman: "I could never lend myself to any transaction, however respectable, that would commercialize on the prestige and dignity of the office of the presidency."

Truman's fortunes turned after Life Magazine advanced him money for an autobiography, and later he received a pension of $25,000 a year -- the first president to do so under a new law. That was plenty for where he lived, the family home in Independence, Mo.

Lessons from WWII: When Only a Czar Will Do

Following up on previous "lessons from WW2" posts about Harry Truman's pursuit of war profiteers, and Henry Kaiser's production miracle. Behind those bright lights were plenty of sparks.

Ramping up the arsenal of democracy in 1940 and 1941 set off fights over money and raw materials that dragged in just about everybody: old and new federal agencies, an Army and Navy intensely jealous of each other, industries, farm-belt politicians, unions, and Congress.

One of the first to hit the headlines concerned the feedstocks for synthetic rubber. Rubber was critical to defense equipment and transport, but Japanese occupation of the Dutch East Indies had cut off 95 percent of natural rubber shipments to the U.S. How to fill a quarter-million-ton-per-year shortfall with synthetic rubber set off a very public battle about which production process (and therefore which feedstock) to use.

Should the new synthetic-rubber factories depend on ethanol from patriotic American corn farmers, or oil from patriotic American oil producers? Arguments went beyond lobbying to a fistfight between the rubber administrator and a newspaper publisher in a swank Washington club.

Nobody was really in charge of the U.S. war effort -- at first. Take the single commodity called petroleum: by early 1942, six “alphabet agencies” competed to direct the production and consumption of products from crude oil. Harry Truman (along with Republican leader Wendell Willkie) called for one man at the top to oversee decisions and to be responsible for the outcome.

At their urging, FDR finally decided to entrust all war production planning to a single man, a czar of czars, former Sears & Roebuck executive Donald A. Nelson. Industrial historians say this decision was the turning point of the entire war effort, though FDR had delayed the decision almost to the point of disaster.

Nelson oversaw many sub-czars, such as Admiral Jerry Land, the head of the Maritime Commission. Land decided how many ships the U.S. needed, who would build them, what cargoes they would carry, and when they would sail. Land also commandeered all civilian-owned ships (both U.S. flag and also foreign ships that happened to be in our ports) for the duration.

After Nelson took over, the war mobilization became one big tent rather than a scattering of little tents. That is, there was plenty of work and opportunity for all Americans and most businesses, but under a single overarching plan.

Henry J. Kaiser: Miracle Man of the WWII Home Front

In a previous post I had mentioned that Henry J. Kaiser -- hardly remembered now outside of his health-care organization he set up -- is one of my industrial heroes. The amazing story of Kaiser, instant shipbuilder extraordinaire, shows how fast a well-managed industry can fill a production gap during emergencies, even while looking out for its workers’ welfare. I wrote about it in this article for Invention&Technology, and had the privilege of interviewing some of Kaiser's key men at his fastest shipyard, including Clay Bedford.

In 1940, Kaiser was a construction contractor who had helped put up Hoover Dam and Grand Coulee Dam and the Oakland Bay Bridge in record time. Other contractors knew him for his skill at motivating people, his ability to exploit latest technology to raise productivity, and the odd fact that he painted all his concrete trucks pink because pink was a “happy color.”

While Kaiser knew nothing about building 10,000-ton ships in 1940, his company came up with a way to mass-produce them so effectively that it ranked as the world’s premier shipbuilder by 1942. His brand-new shipyards in Oregon and California set speed records for freighters and tankers that have never been equaled.

One very effective method was “athletic industrialism” that pitted vast teams against each other and measured success in quality, cost-cutting, and speed. The man the press called “Sir Launchalot” or “Hurry Up Henry” also took care of his enormous workforce with subsidized housing, free day care centers, and a low-cost health-care system. He laid down a trolley line in Oakland, virtually overnight, to make workers’ commuting easier. Equal in importance to the bridge of ships, he gave heart to Americans at an early stage of the war when no military victories were in sight.

Suddenly FDR’s demands for other war equipment began to look more inspiring than insane. (When calling for US tank production to jump from four tanks per year to 45,000 per year by 1943, FDR had assured his aides, “Oh, the production people can do it if they really try.”) FDR considered Kaiser for the vice-presidential slot in 1944.

What’s the take-away from this astounding turnaround? Peter Drucker found his lesson in Kaiser’s optimistic ignorance: since Kaiser didn’t know how traditional shipbuilding worked, he was free to try new ways. (I believe Kaiser's success was more complicated than that, but Drucker's take on it was interesting.)

Kaiser did more than assemble ships. He created an entire system including iron mines and a new steel mill. Kaiser’s approach still offers solutions for emergency mass production, harnessed competition, cost cutting, and worker motivation. His approach could be applied productively to building the ships needed to tap “ocean thermal energy” from tropical waters. Fleets of giant floating plants could produce liquid ammonia in vast quantities for factories and power plants requiring process heat, and for fueling vehicles as well.

San Bruno Gas Explosion: NTSB's Preliminary Report

In my previous post on the NTSB's docket page for the San Bruno gas-pipeline blast, I mentioned that the docket was light on data, but the seven photos were worth a look and the Board would be adding more information as it developed.

Three days ago the Board added a three-page report with new detail about pipeline steel, wall thicknesses, segments, corrosion protection, and fracture locations. Now we know this was an above-average grade of 30-inch-diameter steel pipe (0.375-inch, grade X-42, minimum yield strength of 40,000 psi). Thicknesses reported by the NTSB have been close to the nominal, between 0.36 and 0.38 inches. There's no indication in this report of large corroded areas due to pooled moisture, but highly localized stress corrosion cracking is probably something they're still looking into. SCC can happen when corrosion gets a grip on a little flaw in the metal. The combination of corrosion at the tip of a micro-crack, fed with pulses of energy, can cause these tiny cracks to slowly get longer until they reach a critical length, at which they fail at supersonic speed.

The loss of two Comet jet airliners over the Mediterranean in 1954 was probably due to slow, incremental fatigue cracking as the fuselage flexed with pressurization: that's because the cabin inflates, then relaxes slightly as pressure-relief valves balance it out. Remember, in the world of disasters, little things add up!

Yet to come are micro-level test reports about fracture edges and the most likely starting point. The report mentions that "key fracture surfaces" have been cut away for lab analysis and I'd bet these are suspected starting points.

Some info is provided on the 28-foot-long stretch of pipe that, about halfway down its length, includes the rupture that is the special focus of NTSB interest. Right now the description of pipe sections are in text and therefore it's hard to visualize the joints in the length of pipe removed from the excavation. The NTSB writes about the stretch of pipe as two segments: the south segment, about twelve feet long, and the north segment, about sixteen feet long. The "rupture" is between those two.

The north segment includes two short sections (called pups) that were joined with girth welds. Girth welds are where pipes are joined end to end; the other kind of weld is the longitudinal weld, which is done at the factory -- this is where steel plates are rolled into a tube and welded along a seam. Unstated is why the pups are there: were they part of a rebuild since the line went down in 1956? Were they necessary from the first so that the pipe could make a bend at this location, say because it's at the bottom of a hill or it was making a turn? There have been press reports that this area of pipe had enough of an odd shape that the standard testing pigs couldn't slip through; the pups might be part of the reason for this.

In preliminary reports the Board leaps to no conclusions (recall, there is no probable cause finding until the investigation is winding up). Still, a close reading of a preliminary report can shed a little more light about which suspected contributory causes are still "of interest." This list is usually quite a bit shorter than the list of hypothetical ones bounced around by press reports (and commentators like me) in the first two weeks.

One of the live issues continues to be a pressure pulse. Though not one that "pegged the needle," it came just minutes before the rupture. While it could be a coincidence, and likely isn't the whole cause, it's getting the NTSB's attention and rightfully so.

The pressure pulse arose out of a chain of events (in general I call these system fractures).

The timeline started with maintenance work at the Milpitas Terminal 40 miles southeast of ground zero, which is upstream in flow terms. Milpitas has SCADA controls that are part of the pressure regulation. Some cause, presumably human error but not conclusively, caused the 24-volt DC so-called "uninterruptible power" at Milpitas to fall to 7 volts, which dropped all or part of the terminal's SCADA system offline. Without its link to Milpitas, a remotely controlled valve on Line 132 moved to a pre-set uncontrolled position, from partially open to full open. This allowed the transmission-line pressure as measured at a point downstream of ground zero to climb above the maximum operating pressure of 375 psi. The location of these measurements was Martin Station in Daly City.

About 6:00 pm, eleven minutes before the rupture, pressure at Martin Station peaked at 390 psi. Then eight minutes later it dropped slightly to 386 psi, probably due to automatic pressure relief valves. At 6:11 pm it fell rapidly to 290 psi due to the rupture at San Bruno.

At 6:45 PG&E mobilized an emergency team to isolate Line 132. This delay has attracted much criticism considering that the flames were visible 10 miles away and 911 calls began flooding in at 6:11 and 59 seconds. PG&E closed an upstream valve at 7:20 and the downstream valve at 7:40. The total volume of gas released was about 48 million cubic feet. Firefighting work continued at individual homes due to gas-fed flames from the broken house lines. PG&E shut down the distribution lines to the neighborhood at 11:30 pm and the last of the house fires quickly came under control.

Is the pressure pulse a smoking gun, in CSI terms? Maybe part of one. As far as we know from the instrument readings at Martin Station, the measured peak of 390 psi was still 10 pounds below the maximum allowable operating pressure of 400 psi. Just browsing the Web, I see burst-pressures a good deal higher than that for pipes made out of 0.375-inch X-42 steel. But cracks in the wrong places can bring about anything down. If the nearby sewer line work two years earlier played a part, there might not be any marks on the gas pipe at all; a lateral shifting of the soil due to the sewer-line work could have raised the stress on some gas-line welds. The fracture analysis at the Board's materials lab in DC will tell us a good deal.

Here's an example of an NTSB materials-lab report, prepared for the Flight 587 crash investigation. So my advice is to stay tuned, and trust the process.

Land of the Leftovers: Technological Time Capsules

Rhode Island lawyer Leo Connors had always thought that his office on the 30th floor of Providence’s art deco Fleet National Bank Building (now the Bank of America Building) was at the very top.

But one day in 1953 he found an unmarked door opening on a narrow upward stairway. Passing through two more doors, he entered a long-forgotten, rectangular room fitted out as a dirigible cabin. It had wicker chairs, dark leather-lined walls, vintage light fixtures, fine brass fittings, and a liquor closet. Windows on three sides were framed like those of the Graf Zeppelin, which had been thrilling the public when the skyscraper was new. Altogether the dust-covered room looked like an artifact from some pinched-off timeline, an alternate past in which falcons had to share their aeries with blimps and zeppelins.

But the day of powered gasbags never came to Providence. Shortly after the lounge was finished and furnished in 1928, a string of airship crashes erased all hope for a worldwide web of lighter-than-air routes. England abandoned plans for Britain–Egypt–India–Australia route after the R101 flew into a French hill in 1930. Then the United States canceled plans for a dirigible fleet after a series of disasters that culminated in the loss of the Navy’s great aviation pioneer, Adm. William A. Moffett, when the Akron went down in a storm in 1933. Just about everyone else gave up after seeing the newsreel taken at the Hindenburg’s mooring mast in Lakehurst, New Jersey, in 1937. Meanwhile, in terms of all-around performance and reliability, airplane builders zoomed ahead of the dirigibilists.

Today ornithologist Joe Zbyrowski uses the now dilapidated dirigible room in Providence as a blind for his raptor studies. We'll never know what the exact purpose was: rich boys' clubhouse, or an honest-to-God boarding lobby for users of the air yachts that Goodyear hoped to build so long ago. The builders provided a door giving access to the parapets outside, so I'd vote for the latter. There are more such reality-jarring time capsules out there ... fodder for later posts.

Before FEMA: Arthur Woods of the NYPD

Early in the Twentieth Century, one man showed the rest of the country how to organize millions of people to handle disaster. He was Arthur Woods, commissioner of the New York Police Department (NYPD) from 1914 through 1917. The effort he led in the raucous and dangerous city of New York shows how emergencies can be managed effectively at the local level.

It began during his first months in office. Fearing that war in Europe was going to lap onto American shores, Woods ordered the department to prepare for catastrophe. Disaster response and rescue work had never been a formal part of police work before Woods' arrival, but he saw it as the best way to change his department's image. This was at the cost of some friction with the Fire Department, which saw the police as tromping on their emergency-services turf.

The disaster-preparation work that Woods mobilized was more thorough than anything contemplated by today's state or federal emergency responders. Plans were written up to handle mass uprisings on the scale of the 1863 draft riots; all of Brooklyn burning down; the most powerful hurricane ever recorded on the East Coast; and a direct attack by German battleships and saboteurs. How so? The NYPD identified all telephone and telegraph exchanges so officers could guard key equipment from German saboteurs. In case the exchanges were blown up officers were trained and equipped with semaphore signals. That would require standing on rooftops, so officers got ready for that by locating roofs with the best sight-lines.

The NYPD took stock of all buildings that held supplies of clothes, tools, food, and fuel. These inventories were so detailed that index cards showed where all bakeries were located and how much bread each could produce in a day if supplied with a specific quantity of flour.

What if the civilian bakers ran off? Woods had plans for that, too: he sent hundreds of NYPD officers to learn about high-production baking at Army kitchens.

The NYPD mapped churches and schools to provide sleeping quarters for 50,000 refugees, then went on to identify sources of lumber and canvas to erect tent cities if the flood of displaced people filled even that.

In case police officers were called off to do battle with the Germans, Woods trained and equipped a 12,000-man (and -woman) Home Defense League to stand in for the officers. Here's a link to a newspaper page showing 500 clerks of the B. Altman department store training for the HDL by doing calisthenics on the roof.

The Home Defense League, which was probably the best publicized of Woods' efforts, drew from all walks of life for its volunteers, from street sweepers to bankers and stockbrokers. Society women signed up their automobiles for service and offered themselves as drivers, in case of war. It was no tea party: the women donned khaki uniforms and couldn't graduate till they demonstrated how to carry out major repairs, down to grinding valves, troubleshooting carburetors, and disassembling magnetos.

It was a stunning turnaround in civic life for a city that had mostly given up on its police by the time he took office. Who was this man? After graduating from Harvard, Woods started his career as a teacher and schoolmaster at the Groton School (FDR was among his pupils). Then he worked as a newspaper reporter at the New York Evening Sun covering new types of detective work in the U.S. and abroad. He served a short term as deputy commissioner for the NYPD, then went off to Mexico to run a mine in the mountains.

When Mayor John Purroy Mitchel of the Fusion Party won office in a wave of revulsion about the Tammany political machine, Mitchel appointed Woods as police commissioner after two other candidates turned the post down. Mitchel told Woods to take whatever approach he thought best to straighten up the department. Even crime reporters who knew Woods and liked him personally held little hope. No previous commissioner, including Teddy Roosevelt, had been able to achieve more than temporary fixes.

Instead, within three years (and in addition to all his disaster preparation) Woods turned the NYPD into a model of crime-fighting. Woods launched an attack on robbery, pickpockets, gambling, prostitution, and shakedowns. He took on, and dispatched the extortion ring called the Black Hand. Nobody had been able to attack the roots of it before -- a valiant attempt had cost police Lt. Joseph Petrosino his life in 1909 -- but in three years of Woods' administration the rate of extortion bombings dropped by 92 percent.

He valued prevention above all, and to that end he enlisted thousands of children from the tenements into a Junior Police corps, and put a social worker in each troubled precinct. He closed off streets so children could play safely after school. He installed a basketball court at each police station for use by the neighborhood and police officers. Officers were told to get fit or get out.

After Mayor Mitchel lost the election in 1917, Woods left office to serve in the U.S. Army. Despite the short term in office his influence lingers. The reason the NYPD excels in heavy rescue today traces back to Arthur Woods, and his determination to change the police image from "copper to helper."