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FRIDAY, MAY 15, 2009
Thirty Seconds of Confusion
From a certain website that I'm not supposed to link to or even post to, I guess....
Beep!
"Three thousand for two thousand."
It was a dark night; the landing lights lit up the thick layer of clouds slipping rapidly around us. The plane bobbed rhythmically in light turbulence as we descended at flight idle power. Paul, my First Officer, slid his seat forward and cleared his throat.
"I was talking with what's-his-face the other day, our ALPA communications guy."
I looked over at Paul. "Yeah? What about?"
"Advertising. It occurred to me that we could do a much better job of getting out our message to the general public."
"Definitely."
"So why don't we put out some ads that capture people's attention?" Paul continued. "I was reading a magazine the other day, and there was this really brilliant ad. It featured a lovely voluptuous young lady, and she didn't have any clothes on - this was taken from the back, mind you - but this ad was for -."
PPPPPRRRRRBBBBBBBBTTTTTTT! DING DING!
The cockpit erupted into a cacophony of alarm horns and lights as the autopilot disconnected and the yoke began vibrating furiously. I snapped back to the instruments to find the airspeed dangerously low and the torque still at idle. I grabbed the yoke and shoved the power levers forward. "Set power!" I commanded.
It was obvious what had happened, we had leveled off at 2000 feet during the conversation without me noticing and bringing the power back up. Now, with the engines at full power, the airspeed stopped decaying and started creeping back. The stick shaker stopped momentarily.
"Altitude!" Paul called out.
Crap, we had drifted below 1900 feet. I applied some back pressure to the yoke. PPPRRRBBBBTTTT - the stick shaker started up again and the wings began a light burbling back and forth. Ish, don't want that. I eased the back pressure and gingerly nursed the altitude back to 2000 feet. The airspeed finally crept up to a safe number and I started breathing easier.
Fortunately for my career, this incident took place in a SF340 simulator rather than the JungleBus, and my "First Officer" was actually the director of training for a well-known regional airline. This company does stall training completely differently from most airlines, and in the aftermath of Colgan 3407 and Turkish 1951, Paul invited me to fly their jet and turboprop simulators and experience it for myself. We did departure stalls just after departure, approach to landing stalls while approaching for landing, and high altitude stalls at high altitude. A great many stick shaker events in the real world involve distraction at a critical time while on autopilot, so we did the scenario described above. While all of this might seem quite logical to an outsider, it is actually a revolution in the airline world. Moreover, it is done in apparent contravention of the FAA's Practical Test Standards.
In the last few days, a great many pilots - including some of the commenters on my last post - have been asking what in the world could possess a presumably competent airline pilot to pull up in response to a stick shaker - or for that matter, to use 80 to 120 pounds of force to override the stick pusher that might've saved his life. It's the most puzzling aspect of this crash. Even if the crew was relatively inexperienced, it is drummed into pilots from day one that you don't pull up in response to a stall. What could cause an airline pilot to abandon this most elementary of precepts?
Even if the pilot did survive to answer for his actions, I'm not entirely sure that even he could've given a satisfactory answer to the question. Since he is not around, all we - or the NTSB - can do is speculate about some of the possible culprits and do our best to eliminate them as potential causes of future accidents. There are three primary possibilities that have been discussed: 1) the Captain was a poor pilot to begin with; 2) he simply got confused in the heat of the moment; 3) there was some latent defect in his training. These are not mutually exclusive theories, all three could have come into play simultaneously.
By now it has been widely reported that the Captain failed five checkrides in his career. The first was his instrument checkride, back in 1991, on the partial-panel VOR approach and the NDB approach. He disclosed this failure on his application at Colgan. The next two failures, on his Commercial-Single Engine and Commercial-Multi Engine rides, took place in 2002 and 2004 respectively, and were disapproved for a fairly wide range of tasks. He only disclosed the instrument ride failure on his application. At Colgan, he failed a recurrent Proficiency Check as a First Officer and his upgrade/ATP ride. He also had to repeat a small portion of his initial PC as a new FO in the SF340.
There are a great many capable pilots who have a checkride bust or two in their past, but a long string of them raises warning flags. The interesting thing is that when you read through the NTSB Human Performance Group's interviews, everyone describes Captain Renslow as a good, consciencious pilot. Many FOs he flew with described him as above-average. Perhaps it's simply a case of not wishing to speak ill of the dead, but if he really struggled on the line you'd think the NTSB could've found someone who would have told them about it. It's hard to reconcile the popular Captain with all the checkride busts. It's possible that he simply wasn't a good test taker. That's not insignificant for our purposes: falling apart on tests can be a symptom of not coping well with pressure, period.
There was plenty of pressure to be had in the last thirty seconds of Colgan 3407. That the stick shaker was a complete surprise is self-evident. We don't know where the Captain's attention was in the moments before stick shaker activation; perhaps looking at the wingtips to see how the deice boots were coping, perhaps around the cockpit to see if anything had been missed during the rushed descent and approach checks. Maybe the long day had got to him and he was simply zoning out. It doesn't really matter; it's very unlikely he had any clue that the stick shaker was coming before it went off. It is difficult to explain to those who have never flown airplanes with stick shakers just how jarring their activation is - even in the sim, much less the real world. The whole idea behind them was to have one signal in the cockpit that is so overpowering and unmistakable that the crew cannot possibly ignore or misinterpret it. Both yokes shake so heavily that you can feel it even if your hands are nowhere near the yoke. Loud clattering noise fills the previously quiet cockpit. The autopilot disconnects with the accompanying lights and aural warnings. In the Q400's case, this is a loud horn that repeats over and over until you acknowledge it by pressing the autopilot disconnect button on the yoke. The Colgan crew never did so - they had their hands full enough already - and that sound must have surely contributed to the chaos and confusion that filled that cockpit in the last 30 seconds.
The sudden cacophony had a clear meaning: do something, now. The Captain indeed reacted very quickly, within half a second. More than a few pilots have suggested that he had tail stalls on the mind. It's possible. He'd just transitioned from an airplane that was known to be susceptible to tail stalls (early models, anyway) and had recently viewed the NASA video on tailplane stalls in recurrent training. The crew had been talking about the icing only a few minutes before. With a tailplane stall, of course, one would not expect to see the stick shaker activate, as that indicates a high aircraft angle of attack and, by extension, a low tailplane AoA. I'm not sure that the distinction would be evident to anyone within the space of a half-second, but by the same token I'm a little skeptical that anyone would think of a tailplane stall within a half second in the first place (much less remember that the corrective action for a tailplane stall is to pull up). It's possible that five or six seconds later the Captain mistook the stick pusher for a tailplane stall (they would feel similar in an aircraft with unpowered flight controls, although not in a Q400) and that's why he fought it. It's very easy to play these parlor games after the fact, having reviewed the NASA video and FAA circulars and discussed among ourselves. At the time, caught by surprise and with little idea of what's going on and events moving far faster than he could really think about them, I rather doubt that the Captain consciously thought about what he was doing, in the same way that the First Officer obviously wasn't thinking about what she was doing when she retracted the flaps in the middle of a stall. Amid the confusion, pure instinct took over.
Why that instinct might involve pulling when new pilots are taught over and over again to push may have its roots in the way that most airlines teach stalls. To begin with, they are not even stall recovery procedures; they are stick shaker recovery procedures. The ATP PTS directs you to recover at the first indication of a stall, which includes the stick shaker. Many pilots will never experience a stick pusher or a real stall in the simulator unless they request it; it was never part of the syllabus at Horizon or NewCo. The maneuver is typically taught and checked well above the ground. The setup is far from realistic: the applicant usually hand-flies and stops trimming well before the stall. The reason to do so is that it makes the recovery easier: the plane won't pitch up when you apply power. The purpose of stall training is really to prepare the student to pass the maneuver on the checkride rather than to prepare them for the possibility of being surprised by a stick shaker on the line.
And this brings us to the most outrageous thing about stall training at many airlines. Applicants are taught to hold their altitude throughout the maneuver. Again, this is due to the Practical Test Standards, which state that an applicant must:
Recover to a reference airspeed, altitude and heading with minimal loss of altitude, airspeed, and heading deviation.
The FAA never defines "minimal loss" of altitude. A great many instructors and check airmen have substituted their own standard, often 100 feet as several Colgan instructors testified. People can be and have been failed for trading altitude for airspeed during a stick shaker recovery. Instead, you are taught to immediately go to full power, and use whatever yoke force is needed to keep the airplane level while it accelerates. This often involves "riding the shaker" for some time. Let me say that again: we are being taught to stay in the shaker for longer than is necessary. Because we stop trimming at such a high airspeed, this can involve significant back force on the yoke until the airspeed increases again. Therefore, you are developing the exact motor memory that, if applied to a real-world situation like Colgan 3407's, will induce exactly the wrong control movements.
It's entirely possible that the Captain was reacting to the stick shaker exactly as he did in the simulator and simply overreacted a bit with the adrenaline rush. It didn't take that much back pressure to start the abrupt pitch-up after the shaker, only about 25-30 pounds according to the Flight Data Recorder. The fact that the autopilot was engaged right up to the stick shaker meant that the plane was trimmed for the speed at which the autopilot disengaged, which certainly didn't help matters when the Captain shoved the power levers forward during the pitch-up. I don't doubt that he was as surprised as anyone that his reaction to the stick shaker induced a 30 degree pitch up and subsequent stall. It was still a recoverable situation at that point; it was fighting the stick pusher the whole way down and retracting the flaps mid-stall that ultimately doomed the crew. These actions may reasonably be attributed to panic at a situation that had quickly spiraled out of control.
So why did stalls come to be taught this way? I think I see the FAA's original reasoning. A lot of training and checking used to be accomplished in real transport category aircraft, many of which reacted very poorly to full stalls. In the interest of safety, the FAA decreed that recovery be initiated at the very first sign of a stall. Simply increasing one's airspeed from a low number to a high number doesn't seem like a very difficult task, and nobody wants crews to be diving transport category jets at the ground in a low-altitude situation, so the FAA added the language about minimum loss of altitude. Transfer this to the simulator, where the element of danger is removed, and many check airmen began treating it not as a survival maneuver but a proficiency maneuver not much different than steep turns.
Many major airlines at least include simulator training to the stick pusher for their pilots, but as far as I know only Paul's regional airline has completely revamped the way they do stall training. They teach their pilots that reducing angle of attack promptly is the most important thing in recovering from a stick shaker, and that this involves both increasing power and lowering pitch to trade some altitude for airspeed. I tried both their method and the traditional method in the sim, and using the new method resulted in far less time spent in the shaker in exchange for altitude loss generally no greater than 200-300 feet (the scenario I described at the beginning of this post was using the traditional recovery method). Just as importantly, this airline trains and checks stick shaker recoveries using the most common scenarios in which real crews have encountered stick shakers: accidental reversion to pitch mode after takeoff, mountain wave at high altitude, leveling off on a non-precision approach, and turning base leg to final approach. Most scenarios involve the autopilot being on and trimming all the way to the low airspeed. They often give students low speed scenarios when they're not expecting them, and make ready use of distraction. In my own case, I knew exactly what Paul was doing when he struck up the conversation about the ad with a naked woman in it, yet I still found myself surprised when the shaker went off. The end result is that if one of their pilots ever finds themselves surprised by a stick shaker at low altitude, it won't be the first time they've had that experience, and they'll have accurate motor memory to call upon for the recovery.
So why haven't more airlines changed the way they train stall recovery? Surprisingly, the FAA isn't standing in the way: they wholeheartedly approved of the changes that Paul introduced to his airline's training program. A lot of it is simply institutional inertia. Until now, few have thought there was a problem that needed addressing. This a symptom of a reactive rather than proactive safety culture at many regional airlines. Another element is cost: many regionals' training programs are all about turning out pilots as quickly and cheaply as possible while maintaining a basic level of competence and safety. When you compare regional airline training syllabi to those at major airlines, you typically see fewer simulator sessions despite having similarly sophisticated aircraft and less experienced pilots. That means that certain things get glossed over, and no "superfluous" training is included. This accident will of course change the way we teach stalls - I fully expect to be using Paul's method next year (and I hope they call it "Paul's method" in recognition of his foresight) - but I do worry that it will take future accidents to expose other weaknesses unless there is a fundamental change in the safety culture at the regional airlines. I'll write more about that in my next post.