Comments about technological history, system fractures, and human resilience from James R. Chiles, the author of Inviting Disaster: Lessons from the Edge of Technology (HarperBusiness 2001; paperback 2002) and The God Machine: From Boomerangs to Black Hawks, the Story of the Helicopter (Random House, 2007, paperback 2008)

Friday, May 18, 2012

Superjet-100's Voice Recorder: Found

After a great many conflicting news stories, it's finally settled that one recording device has been recovered from the Superjet 100's crash site on Mt. Salak, Indonesia. The National Transportation Safety Committee will download data from the cockpit voice recorder's solid-state memory boards this weekend.

Here's a photo of the CVR, which searchers found among debris from the tail empennage:
It looks like the FA2100 model from L3 Aviation Recorders. I feel confident in guessing that the data is intact. Even though the jet flew full speed directly into a cliff, because the flight data recorder and cockpit voice recorder are in the tail, that permits a good deal of deceleration prior to impact.

It doesn't matter that in general the unit looks pretty beat up. The only part that matters is this large dome-shaped unit, snipped from the official photo:
That's the crash-survivable memory unit, or CSMU. It's got a stack of flash-memory boards inside. It's probably intact because it's designed to tolerate pressurized seawater (down to 20,000 feet), sustained fuel fires, 3,400 G's of impact, and a wide range of chemicals. The dome provides three layers of protection: aluminum on the innermost surface, an inch of ceramic thermal insulation, and a quarter-inch of stainless steel on the outside. Given the small diameter to be protected, that adds up to a lot of protection.

The damage to the metal housing to the left of the CSMU ...
... is irrelevant, because it holds circuit boards for transferring the four channels of voice data into the CSMU. The boards aren't needed after the aircraft is destroyed. Same for the base:
... which serves as a structural chassis, and a convenient location for data and power inputs. It also holds a circuit board.

What about the little tube-like item on the right?
That's the underwater locator beacon, or ULB. It's a pinger that starts sending out acoustic pulses at a frequency of 37.5 kHz upon immersion in water. Here's what a ULB looks like in happier times:

The ULB is the focus of some interest in the event-recorder community, because (as I mentioned in this post) neither ULB attached to Flight 447's data and voice recorders was detected by the pinger-search teams, even though their ships passed almost directly overhead and during the nominal transmit duration (30 days).

I asked a flight data recorder expert about this minor mystery and I gather from his comments that while the cause isn't known, recent ULB tests at a lake in France show that the metal frame of a CVR can "shadow" the transmissions, drastically reduce the detectable range in those directions. Added to the great depth of the Flight 447 wreckage (more than 12,000 feet), it could explain how the pingers could transmit but not be heard. 

It's too early to say what happened in the cockpit prior to the crash, but there's been plenty of speculation in the interim: that the captain and first officer were distracted by promotional duties, perhaps even admitting VIP's onto the flight deck to gaze out the windscreen. If true, that conversation will be preserved on the audio channels.

Wednesday, May 9, 2012

New Russian Jet, Off the Radar

Readers might be wondering how a modern airliner like the Sukhoi SuperJet 100 could stay missing for the better part of a day. 

In this post I wrote about how airliners hardly ever go permanently missing, the most recent a Pakistan International Airlines Fokker-27 turboprop that vanished among the mountains on its way to Islamabad in 1989; no trace was ever found.

No doubt something of the SuperJet 100 and its 44 souls on board will turn up soon, given that whatever happened couldn't have been more than 50 miles from Jakarta and ten miles from an airbase. 

Here's what the plane looks like on the inside, from FlightGlobal:
All we know now is that a half hour after leaving Halim Perdanakusuma Airport in Jakarta, the crew of a brand new SuperJet on a short demonstration flight for airline customers and the press (registration RA 97004) asked ATC for immediate clearance to descend from 10,000 feet to 6,000 feet. Shortly afterward it vanished from primary and secondary radar.

Nor has any information come to authorities via satellites that receive signals from emergency locator transmitters.

Mount Salak, a dormant volcano in the vicinity, tops out at 7,200 feet and another one is even higher. That raised questions about ground impact in the drizzly conditions, but people who live nearby say they heard no sounds of a crash. 

RT reports that the search has now resumed. Pending some evidence, there is speculation in some quarters about a crash-landing at high elevations because some of the passengers' cellphones do ring when called, without anyone picking up.

Tuesday, May 8, 2012

Sole Survivor

Coming back to Minneapolis following a talk last week to the WebEOC Users Conference in Denver, I was reminded of a Viewpoint editorial I wrote for Aviation Week about the danger of collisions among aircraft maneuvering along airport runways. Our 737 was on final approach at MSP International Airport, wheels down and flaps deployed, maybe thirty feet off the ground, when the crew abruptly poured on the power, cleaned up the aircraft, and started climbing. A brief comment from the crew over the intercom explained later that another airplane hadn't cleared the runway as expected, so they executed a go-around. A good thing!

On the subject of crashes on airport grounds ... Station WKYT  in Kentucky yesterday posted a segment of documentary interview with James Polehinke, who was first officer when Comair Flight 5191 crashed in August 2006 during an attempt to take off from the wrong runway at Blue Grass Airport west of Lexington, Kentucky. 

Here's a diagram from USA Today:
Pulled from the wrecked Bombardier regional jet with serious injuries, Polehinke was the only survivor. Deaths totalled 47 passengers and two crew. Here's the nose:
Production of the documentary, Sole Survivor (slated for release in August), is the first time Polehinke has talked publicly about the crash almost six years ago. Relatives of those who were killed say they would like to hear more from him. Here's one of the few pictures of Polehinke that was available before the show's publicity:
 The show's director has been seeking out 17 sole survivors from airplane crashes. 

One of the central figures in the documentary will be George Lamson, the only person who survived the crash of Galaxy Airlines Flight 203 at Reno, Nevada, in 1985. (That Lockheed L-188 crash was chiefly due to distraction among the flight crew, caused by the slamming of an air-start access door that the ground crew hadn't secured before takeoff.)

How did the Bombardier come to earth? Human error. While verbally acknowledging instructions from the tower to take off from Runway 22, instead the crew turned onto 26 that morning. It was a strip intended for general aviation, and too short for the regional jet to reach takeoff speed. The plane's gear made tire tracks along the grass beyond the runway, bounced briefly into the air after hitting a berm, then crashed upon hitting trees.

As with most disasters there were multiple causes of Comair 5191's crash, and not all happened on the flight deck. The layout of runway thresholds was confusing, and construction made it more difficult. There was only one controller on duty at the time; busy with managing his records, he wasn't looking out the tower window when he could have spotted the error.

One chilling factor that jumps out from the NTSB's final report and the CVR transcript is the prolonged and lighthearted talk on the flight deck about personal matters: family, off-duty activities, and career plans. The captain and first officer did get through the checklist, but the aviation talk was frequently interrupted by non-aviation chatter. The cockpit is supposed to be free of such distractions.