4 ms·
A bad AoA probe wouldn't trigger IAS disagreement alert ( that is fed from the separate pitot tubes ) but could activate the corresponding stick-shaker which ma
by dingaling 8y ago
A bad AoA probe wouldn't trigger IAS disagreement alert ( that is fed from the separate pitot tubes ) but could activate the corresponding stick-shaker which may make the pilots consider the possibility of IAS uncertainty.
Just a minor quibble.
Also increasing airspeed isn't a panacea for avoiding a stall, it is entirely possible to enter a high-speed stall if the AoA isn't managed. And in fact as mentioned speed can make recovery more difficult due to airloads on non-FBW aircaft.
- VBprogrammer 8y agoFrom the AD issued after the Lion Air accident: Additionally, pilots are reminded that an erroneous AoA can cause some or all of the following indications and effects: - Continuous or intermittent stick shaker on the affected side only. - Minimum speed bar (red and black) on the affected side only. - Inability to engage autopilot. - Automatic disengagement of autopilot - IAS DISAGREE alert. - ALT DISAGREE alter. - AOA DISAGREE alert (if the AOA indication option is installed) - FEEL DIFF PRESS light
- dingaling 8y agoThank you for the corrections!
- mhandley 8y agoThe bad AoA probe can cause IAS disagree, according to the FAA Emergency Airworthyness Directive: http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgad.nsf/0/83ec7f95f3e5bfbd8625833e0070a070/$FILE/2018-23-51_Emergency.pdf http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgad.nsf/... Take a look at the graphs from the LionAir crash: http://nrg.cs.ucl.ac.uk/mjh/lionair.png http://nrg.cs.ucl.ac.uk/mjh/lionair.png You can see that both airspeed and altitude misread, in addition to AoA. If I understand correctly, the AoA is used by the ADIRU to correct misreading of the static pressure measured by the pitot-static tubes at high angles of attack. Thus one bad AoA probe can cause lots of symptoms simultaneously.