4 ms·
MCAS only operates at high angles of attack, higher than normal flight would encounter. The reason it was even a factor in these crashes was the bad AoA sensor
by ams6110 8y ago
MCAS only operates at high angles of attack, higher than normal flight would encounter. The reason it was even a factor in these crashes was the bad AoA sensor readings. If the AoA data had been correct, MCAS would not have been changing the trim.
- petilon 8y agoWhen an aircraft pitches up, it increases the angle of attack, right? (If not MCAS would not be a fix for the pitching up problem.) And the pitching up can happen during normal flights, correct?
- jcoby 8y ago> When an aircraft pitches up, it increases the angle of attack, right? Yes, but not what you may be thinking. The AoA is the angle of the wing vs relative wind (the angle the wing is attacking the air). You can have high relative pitch (attitude) to the horizon but a low AoA, such as during climb. That same attitude is a full stall at slower speeds/power. The wing doesn't care where the nose points. All it cares about is its relative angle to the wind. Once it diverges past a critical angle the wing stalls. What appears to have happened with these MCAS issues is that the MCAS senses that the AoA is too high when it's completely normal and safe, so it auto-trims down.
- jboles 8y agoThey can be related but not necessarily. Pitch is where the nose is pointed, while angle of attack is the angle at which the passing air hits the wings. The nose can be pointed up with a low angle of attack (e.g. a climb during cruise) and conversely the aircraft can be pitched down with a high angle of attack (e.g. descent approach with flaps extended)
- pdonis 8y ago> MCAS only operates at high angles of attack, higher than normal flight would encounter. This is true for climb and cruise, but not necessarily true for a bank.