I’m reading about the Boeing 737 Max 8 incidents involving Lion Air Flight 610 and Ethiopian Airlines Flight 302.
In both flights, erroneous AoA data from the pilot side AoA sensor fouled airspeed and altitude measurements for the pilot side FCC which triggered an airspeed disagree and altitude disagree with the correct First Officer FCC.
My question is how is AoA data used to calculate altitude and airspeed, I’m an aerospace engineer and in school we are taught that conventionally, things like altitude and airspeed is measured with static pressure, stagnation pressure etc.
I can’t find any straight forward answers online other than folks on Quora taking a whole essay to say “well AoA data is used to calculate it in the ADIRU” which doesn’t explain anything.
Edit: I just remembered how AoA is used to correct pitot-static pressure and varying angles of attack because the tube isn’t head on into the incoming flow but that still leaves the question of altitude? are they incrementally multiplying the velocity by time to get a displacement and taking the sin(pitch) to get altitude? that’s my guess.
In: Engineering
Altitude is typically a separate measurement, from the altimeter, but you might be referring to rate of climb, which is something the air data computer can calculate.
The pitot tube doesn’t swivel, so it only points directly into the path of motion at the trim AoA. Other AoAs cause it to read low, and the AoA indicator is used to calculate a correction.
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