Stall. A fundamental flight fail, yet so shrouded in myth that few pilots can describe it correctly. It takes but a few seconds to recover from a stall. But it is now apparent that many pilots out there cannot even recognize a stall.
The airplane doesn’t care if you don’t understand. It will just kill you.
This is a scary story.
Aside from the nutcase conspiracies about aliens abducting airliners, there is little disagreement about the Colgan Air crash in February, 2009.
The Captain failed five previous performance and proficiency checks. The First Officer, paid “food stamp wages,” lived with her parents in Seattle, Washington. She hitchhiked on airliners across the entire United States to report for work in Newark, New Jersey, the night before the crash.
The pilots squatted in the airline crew lounge the whole night and day before the flight, a violation of airline policy. Hotels and ‘crash pads’ were expensive.
At 10:10pm local time on February 12, 2011, Colgan Air flight 3407 was descending past 5,000 feet on approach to its destination, Buffalo, NY. The one-hour hop from Newark was punctuated by the Captain’s one-sided chit-chat about jobs, pay, air traffic control.
They were landing in 10 minutes.
Cockpit voice recorder transcript. “Hot-1” = Captain’s hot mic, “Hot-2” = First Officer’s hot mic, * and # = expletives deleted. CAM = cockpit area mic.
22:10:22.6 HOT-2 is that ice on our windshield?
22:10:25.6 HOT-1 got it on [the wings on] my side. you don’t have yours?
22:10:28.7 HOT-1 * [sound of whistle]
22:10:30.5 CAM [sound of click]
22:10:32.3 HOT-2 oh yeah oh it’s lots of ice.
22:10:47.5 HOT-1 oh yeah that’s the most I’ve seen — most ice I’ve seen on the leading edges in a long time. in a while anyway I should say.
22:10:51.4 HOT-2 oh *.
22:10:57.7 HOT-2 yeah that’s another thing. all the guys— @ came in to our when we interviewed and he said oh yeah you’ll all be upgraded in six months into the Saab and blah ba blah ba blah and I’m thinking you know what. flying in the northeast I’ve sixteen hundred hours. all of that in Phoenix how much time do you think actual I had or any in in ice. I had more actual time on my first day of IOE than I did in the sixteen hundred hours I had when I came here.
22:11:21.0 HOT-1 [sound of laughter]
The First Officer had never had ice before. Ice changes the shape of the wing.
22:11:31.5 HOT-1 but uh as a matter of fact I got hired with about six hundred and twenty five hours here.
22:11:37.6 HOT-2 oh wow.
22:11:39.4 HOT-1 uh.
22:11:39.9 HOT-2 that’s not much for uh back when you got hired.
22:11:42.5 HOT-1 no but uh out of that six and a quarter two hundred fifty hours was uh part one twenty one turbine. multi engine turbine.
22:11:50.0 HOT-2 oh that’s right yeah.
22:11:54.3 HOT-2 no but all these guys are complaining they’re saying you know how we were supposed to upgrade by now and they’re complaining I’m thinking you know what? I really wouldn’t mind going through a a winter in the northeast before I have to upgrade to captain.
Just 45 seconds later, on final approach, the First Officer said,
22:12:05.0 HOT-2 I’ve never seen icing conditions. I’ve never de-iced. I’ve never seen any— I’ve never experienced any of that. I don’t want to have to experience that and make those kinds of calls. you know I’dve freaked out. I’dve have like seen this much ice and thought oh my gosh we were going to crash.
Less than five minutes later they were dead.
The National Transportation Safety Board made a video based on data from the flight data recorder, or ‘black box’. Remember our last article, Death by Ignorance.
- When the wing is inclined too steeply against the airflow, it no longer rides the oncoming air.
- With the wing dragging in the airflow, flight becomes impossible, the wing stalls, and the airplane starts to fall.
- Do the right thing –-> point the airplane down. Lower the nose, reduce the angle of attack, restore the airflow over the wings, and fly again.
Then there is Langewiesche, in 1944.
A pilot is killed because he either fails to recognize the stall for what it is, or fails to control that impulsive desire to haul back on the stick.
They had the autopilot on, with ‘Altitude Hold’ engaged, 2,300 feet selected. The autopilot would hold the airplane at 2,300 feet, no matter what. That was their last clearance from Air Traffic Control – maintain 2,300 feet until lined up with the runway, still several miles away.
APP = Approach Control, RDO-2 = First Officer radio mic
22:15:13.5 APP Colgan thirty four zero seven three miles from KLUMP turn left heading two six zero maintain two thousand three hundred until established localizer. cleared ILS approach runway two three.
22:15:22.2 RDO-2 left two sixty two thousand three hundred ’til established and cleared ILS two three approach Colgan thirty four zero seven.
The autopilot does not fly an airplane. All the autopilot can do is point the airplane – left, right, up, down – to hold altitude and heading. The Dash-8 has no auto throttles. Power management is up to the human pilot.
At 22:16:00 they were at 185 knots (nautical miles per hour) of airspeed, level at 2,310 feet. Six seconds later they lowered the landing gear. The drag of the wheels reduced airspeed. The pilots did not add power.
From this point until they hit the ground, just 47 seconds elapsed.
Just 10 seconds later their speed had dropped to 157 knots.
From our last article:
If the airplane slows, the oncoming airflow weakens, and the wing descends. It wants to fly. It was designed to fly. If it gets very slow, it will fly downward.
Unless a pilot tries to make it do the impossible.
The pilots had set the autopilot to hold altitude at 2,300 feet. As the airplane slowed, the autopilot pointed the wings higher to keep the airplane from descending. The pilots still did not add power.
Ten seconds later the speed was down to 134 knots, the low speed warning ‘barber pole’ came out, the wing was running out of airflow, and the autopilot pulled the nose up even higher to try to maintain altitude. The wings were dragging through the air at an increasing angle of attack.
Incredibly, the Captain called for “Flaps Fifteen” and the First Officer deployed the big flaps. This further increased drag and reduced the speed.
One second later the stall horn blared, and the stick shaker activated. Aptly named, this safety device shakes the control wheel violently, telling the pilot, “Let go! Let the nose drop!”
The autopilot automatically disconnected so that the pilot could manually lower the nose, reduce the angle of attack and prevent the stall. So far the safety systems were working.
But the Captain did the exact opposite.
He pulled the control wheel all the way back. The airplane’s nose pitched way up, and the angle of attack went sky high, literally.
The wings, pointed at an impossible angle, were barely flying. The airplane wallowed, rolled hard left, then hard right as the Captain overcorrected,.
Then the stick pusher activated. This was a more drastic safety feature – the airplane tried to take the wheel away from the Captain and push it forward, to lower the nose and get the wings flying again.
The airplane was fighting to save itself from the Captain.
22:16:26.6 HOT-2 uhhh.
22:16:27.4 CAM [sound similar to stick shaker lasting 6.7 seconds]
22:16:27.7 HOT [sound similar to autopilot disconnect horn repeats until end of recording]
22:16:27.9 CAM [sound of click]
22:16:31.1 CAM [sound similar to increase in engine power]
22:16:34.8 HOT-1 Jesus Christ.
22:16:35.4 CAM [sound similar to stick shaker lasting until end of recording]
Without a command from the Captain (a procedure violation), the First Officer retracted the flaps. This reduced drag but made the wings less efficient at low speeds. It didn’t matter. They were 20 seconds away from the end.
22:16:37.1 HOT-2 I put the flaps up.
22:16:40.2 CAM [sound of two clicks]
22:16:42.2 HOT-1 [sound of grunt] *ther bear.
22:16:45.8 HOT-2 should the gear up?
22:16:46.8 HOT-1 gear up oh #.
The Captain struggled to keep the airplane upright. In the end he put in a hard left input, and the right aileron went full down, increasing that wing’s angle of attack even more.
The right wing gave up and stalled completely. The left wing, still flying, rolled the airplane upside down to the right. “Over-the-top” spin entry. The final dive began.
22:16:50.1 CAM [increase in ambient noise]
22:16:51.9 HOT-1 we’re down.
22:16:51.9 CAM [sound of thump]
22:16:52.0 HOT-2 we’re [sound of scream]
22:16:53.9 END OF TRANSCRIPT
END OF RECORDING
One person on the ground and all 48 people in the airplane died.
Here’s the video:
The NTSB report is 285 pages long. I read it all, often astounded, sometimes horrified. The report thoroughly and minutely dissected the crew’s last two days, phone calls, sleep and awake times, spouse interviews, injury chart, aircraft history, etc. It explored crew monitoring failures (nobody noticed airspeed decay), fatigue (commuting, crew lounges, ‘crash pads’), airspeed selection (an eye-opener!), stall training, use of cellphones (the First Officer was texting 2 minutes before takeoff), weather (e.g.. icing).
The NTSB concluded that the probable cause of the accident was
the captain’s inappropriate response to the activation of the stick shaker, which led to an aerodynamic stall from which the airplane did not recover. Contributing to the accident were
(1) the flight crew’s failure to monitor airspeed [despite] the low speed cue
(2) the flight crew’s failure to adhere to sterile cockpit procedures
(3) the captain’s failure to effectively manage the flight
(4) Colgan Air’s inadequate procedures for airspeed selection and management during approaches in icing conditions.
There are 46 detailed findings, including
#5. This accident was not survivable.
#29. The captain had not established a good foundation of attitude instrument flying, and his continued weaknesses in basic aircraft control and instrument flying were not identified and adequately addressed.
#6. The captain’s inappropriate aft control column inputs in response to the stick shaker caused the airplane’s wing to stall.
Number 6 above is precisely and carefully worded. When the stall warning and stick shaker activated, the airplane was not yet stalled (in fact the ref speed switch was set to give an earlier warning of stall). It was not the autopilot, or ice, or low speed that stalled the airplane.
It was the Captain.
When the stick shaker activated, there was a 25-pound pull force on the control column, followed by an up elevator deflection and increase in pitch, angle of attack, and G force. The data indicate a likely separation of the airflow over the wing and ensuing roll two seconds after the stick shaker activated.
Twenty-five pounds of pull on the control wheel overcame the stick shaker and pusher. If The Captain had been a less powerful man, they might all have lived.
Posted from Bangkok, September 2, 2011.
Complete CVR transcript here, from takeoff to the crash.
The entire NTSB report here, 285 pages, facts, data, analysis, conclusions, recommendations. This is a public document and is available on the internet.