(Photo of typical Chinook: Sgt. Sean Casey, Army Times)
Date and Incident: August 6, 2011. During a night-time combat mission to drop off a squad near Wardak Province, a CH-47D Chinook with a quick reaction force on board crashed on approach to landing. Original post on Disaster-Wise is here. (Map: Associated Press)
Setting: Tangi Valley, Wardak Province. Earlier that day, two helicopters had delivered an assault force of Rangers to capture a Taliban leader said to be in the area. The Rangers encountered opposition. Hearing that more Taliban fighters were joining the battle, American commanders ordered reinforcements.
Two CH-47Ds were dispatched; the lead one would carry the entire "immediate reaction force" of SEALs and other personnel to the battle. The trailing helicopter, which carried only the aircrew, was to orbit nearby to be available if needed.
The lead helicopter was on its final approach at 2:00 am when a group of Taliban fighters fired two or three RPG-7 rocket-propelled grenades in quick succession from a mud-brick building 700 feet from the helicopter.
Though it was night and such missiles are unguided, one warhead struck a blade on the aft rotor system, blowing off the outer ten feet of the blade. This threw the rotor out of balance and caused a rapid chain-reaction failure. Having lost all lift from the rotor, the helicopter dropped vertically into a ravine, crashed, and was engulfed in a fuel-ammunition fire.
Consequences: All 38 Americans and Afghans aboard the Chinook died in the crash. It was the deadliest single incident for American forces in Afghanistan since 2001.
Final report: An executive summary prepared by Gen. Jeffrey Colt for the Central Command is here. Key conclusion:
"The decision to load the IRF onto one CH-47D in order to mitigate risk by minimizing aircraft exposure to ground fire and to mass the assault force was tactically sound. The shoot down was not the result of a baited ambush, but rather the result of the enemy being at a heightened state of alert due to 3 1/2 hours of ongoing coalition air operations concentrated over the northwestern portion of the Tangi Valley."
Lessons: While acknowledging the rapid operational tempo in this case, the report recommends careful use of reconnaissance aircraft in such situations: the commander should have a recon aircraft available nearby to scout the area for hostile forces, but its use should be timed so that it comes within earshot only shortly before the assault landing is attempted. (To bring the recon aircraft overhead too early might provide warning to nearby fighters that a landing is imminent.)
My comment: Despite some early speculation that the Taliban used a secret weapon, it appears that this was a freakishly accurate shot considering the distance, the unguided missile, the darkness, and that the helicopter was blacked out.