Originally Posted by
Discorde
@Vessbot: a very detailed and thoughtful analysis but in day-to-day ops the task is either to follow a defined flight path (pitch for path, thrust for speed), or otherwise pitch for speed and thrust for vertical performance.
V/S and FPA modes can be considered as defined flight paths.
Most of us senior aviators find it incredible that none of the three pilots on the flight deck of Asiana 214 noticed the decreasing airspeed until too late.
The NTSB, and common discussion about that crash, describe what happened as “insufficient monitoring of airspeed.” While true in a dry and technical sense, it doesn’t come close to capturing what was really going on. It’s only part of it. It’s like saying that if someone crashed their car straight into a wall at 90 degrees, with their foot on the gas pedal down to the floor, that he had “insufficient monitoring of closure rate to the wall.” I mean OK but... not really.
The failure was at an earlier point in the brain/control loop. By pulling on the stick with XX pounds, he was
commanding the airspeed to decrease by that much! Just “monitoring” implies that they failed to notice some external event that might or might not have come, and they had to be on their guard to catch it in case it did. If they lost airspeed due to a sudden downdraft or tailwind shear, that’s monitoring. If they lost fuel due to a leak, that’s monitoring. If the FA called asking to turn the temperature down because the thermostat went crazy, that’s monitoring. If someone called them on 121.5, that’s monitoring.
If they lost YY knots because they were pulling on the stick with XX pounds, that’s
not just monitoring.
AOA determines airspeed, and they didn’t merely fail to monitor, but rather they
caused that airspeed decrease by pulling on the stick and increasing the AOA.
Someone with an understanding of System 2 sees that clearly; while according to System 1, pitch control is merely for flight path and the airspeed loss was a separate incidental event that they would have caught had they just been monitoring better, like the fuel loss or the temperature in the cabin. No, the connection is causal.
And even in regular everyday flight in the middle of the envelope while following a defined fight path, AOA (even though primarily being used for tracking that path) still determines airspeed just the same. And that fact must be embraced like lives depend on it, because they do.
System 1, while simple and easy for an introductory student to see the direct effect of the controls, is not sufficient to truly understand flight.