Thursday, May 14, 2009
Following Orders
(1)
Beginning beer #3 at 1441L. I'm a bit later than planned, today, after catching up on some TiVo stuff. I have two possible subjects this week: (1) Colgan flight 3407. (2) Stalking.
This NTSB Animation of Buffalow Accident was really quite shocking to me as a former commercial pilot and flight instructor. Indeed, I found it almost unbelievable. Here is the apparent scenerio: They are approaching the Buffalo airport at night in instrument conditions below 10,000 feet. (A bit scary... But they are on autopilot, in contact with ATC. Both may be sleep-deprived and the co-pilot is slightly ill with a cold.) The animation shows them at 180 knots and 2300 feet - very low. Both pilots should be 'all business' here. There were 49 unsuspecting people on board including, apparently, the two pilots. They notice ice on the wings and the co-pilot relates her total ignorance concerning this matter. The pilot agrees that there is quite a lot of ice, maybe the most he has seen. There is no discussion of in-flight de-icing procedures. Meanwhile the gear has been lowered, the flaps set to 5 degrees, and the props set to max rpm. The airspeed rapidly decays under these 'high drag' conditions and the autopilot attempts to maintain altitude by raising the nose, which further increases drag, which further slows the airplane. Meanwhile essential power, which is apparently on manual control, remains at minimum while the pilots chat with each other. As airspeed drops, the AP maintains altitude by 'pulling back on the stick.' It is a classic 'approach to stall' situation which every student pilot is taught right at the beginning of training. The autopilot, deprived of power control, faithfully goes as far as it can go in its quest to maintain altitude by raising the nose. Then, just before the airplane stalls, the autopilot (fearing for its life!) switches priorities from altitude to airspeed, and pushes the nose down after warning the pilot via the 'stick shaker' that the airplane is about to stall due to an extremely high 'angle of attack.' (Notice that the autopilot 'followed orders' right up to the point of absurdity before rebelling, but did not go beyond that point.)
Beginning beer #3 at 1441L. I'm a bit later than planned, today, after catching up on some TiVo stuff. I have two possible subjects this week: (1) Colgan flight 3407. (2) Stalking.
This NTSB Animation of Buffalow Accident was really quite shocking to me as a former commercial pilot and flight instructor. Indeed, I found it almost unbelievable. Here is the apparent scenerio: They are approaching the Buffalo airport at night in instrument conditions below 10,000 feet. (A bit scary... But they are on autopilot, in contact with ATC. Both may be sleep-deprived and the co-pilot is slightly ill with a cold.) The animation shows them at 180 knots and 2300 feet - very low. Both pilots should be 'all business' here. There were 49 unsuspecting people on board including, apparently, the two pilots. They notice ice on the wings and the co-pilot relates her total ignorance concerning this matter. The pilot agrees that there is quite a lot of ice, maybe the most he has seen. There is no discussion of in-flight de-icing procedures. Meanwhile the gear has been lowered, the flaps set to 5 degrees, and the props set to max rpm. The airspeed rapidly decays under these 'high drag' conditions and the autopilot attempts to maintain altitude by raising the nose, which further increases drag, which further slows the airplane. Meanwhile essential power, which is apparently on manual control, remains at minimum while the pilots chat with each other. As airspeed drops, the AP maintains altitude by 'pulling back on the stick.' It is a classic 'approach to stall' situation which every student pilot is taught right at the beginning of training. The autopilot, deprived of power control, faithfully goes as far as it can go in its quest to maintain altitude by raising the nose. Then, just before the airplane stalls, the autopilot (fearing for its life!) switches priorities from altitude to airspeed, and pushes the nose down after warning the pilot via the 'stick shaker' that the airplane is about to stall due to an extremely high 'angle of attack.' (Notice that the autopilot 'followed orders' right up to the point of absurdity before rebelling, but did not go beyond that point.)
