PPRuNe Forums - View Single Post - Boeing 737 Max Software Fixes Due to Lion Air Crash Delayed
Old 22nd Apr 2019, 18:48
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MurphyWasRight
 
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Originally Posted by Smythe
Actually, yes, you can, and the 767 tanker does compare the AoA vane with the gyros. Most unmanned ac do not have AoA vanes, and rely on the inertial system.

Interesting paper showing the results of using different algorithms to estimate AoA

http://www.tc.faa.gov/its/worldpac/techrpt/tc16-52.pdf

Always amused by the CAT designations...from the draft FSB
Aircraft Category
B-737 C
B-737-CL C
B-737-600/700 C (even a 700 at CAT C is a struggle)
B-737-800/900/900ER C or D (CAT C?)
B-737-MAX C or D (CAT C?)
Thanks for the link, very helpful since it provides descriptions and resuls for of a number of approaches, although the classic vane sensor is not included. Have not read in depth yet but did notice this:

AOA DERIVED FROM INERTIAL MEASUREMENTS A third method of estimating AoA was briefly investigated. This consisted of determining the angular separation between aircraft body X-axis pointing angle and flight-path angle, resolved into the aircraft’s plane of symmetry (in level flight, the difference between pitch attitude and vertical flight-path angle). This estimate is shown on some of the AoA comparison plots but compared poorly to the sensed, derived, and calibrated AoA, primarily due to not having a good estimate of vertical flight-path angle.
The other algorithms include a number of other parameters in the mix, seems that inertial sensors (gyros and accelerometers) alone can't provide needed data.

Keep thinking the best thing is to have as many different sensor technologies as possible with intelligent integration and cross checking of them all.
This would (at first at least) not require critical level software if it was done as a separate advisory/diagnostic function.
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