Auto Pitch Trim Freeze High Alpha A320
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Auto Pitch Trim Freeze High Alpha A320
In normal and alternate laws,when exactly does the auto pitch trim freeze when increasing alpha ? The manuals as far as I could glean,only mention the autopilot disconnecting at alpha prot +1.
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Automatic pitch trim freezes in the following situations: ‐ The pilot enters a manual trim order. ‐ The radio altitude is below 50 ft (100 ft with autopilot engaged). ‐ The load factor goes below 0.5 g. When angle-of-attack protection is active, the THS setting is limited between the setting at the aircraft's entry into this protection and 3.5 ° nose down. (Neither the pilot nor the system can apply additional nose-up trim). Similarly, when the load factor is higher than 1.25 g or when the aircraft exceeds 33 ° of bank, the THS setting is limited to values between the actual setting and 3.5 ° nose down. When High Speed or High Mach Protection is active, the THS Setting is limited between the setting at the aircraft's entry into this protection and 11 ° nose-up.
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Auto Pitch Trim Freeze High Alpha A320
If I understand right,in Normal law,the sequence approaching alpha floor would be : Autopilot disconnects,pitch trim freezes and then alpha floor kicks in. What about in alternate law ?
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Originally Posted by Creases67
In normal and alternate laws,when exactly does the auto pitch trim freeze when increasing alpha ?
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A320 Normal Law, FL350
Autopilot disconnects middle of the Alpha Prot range.
With continuous manual sidestick back pressure, Autotrim continues to function.
Autotrim gave pitch up command even while on the Alpha Prot range until a little BELOW ValphaMax, then gave a slow pitch down trim.
If you keep on pulling back the sidestick (did it with both hands to keep it in the full aft detent) the speed oscilllates around ValphaMax.
Observation: Autotrim kept on functioning all the time, but seemed to be reacting to the Vertical Speed, i.e., if the VSI went negative, Autotrim commands pitch up even when within ValphaMax; when VSI recovers to positive (approx 1300fpm w GW of 65T) Autotrim gave pitch down command.
Autopilot disconnects middle of the Alpha Prot range.
With continuous manual sidestick back pressure, Autotrim continues to function.
Autotrim gave pitch up command even while on the Alpha Prot range until a little BELOW ValphaMax, then gave a slow pitch down trim.
If you keep on pulling back the sidestick (did it with both hands to keep it in the full aft detent) the speed oscilllates around ValphaMax.
Observation: Autotrim kept on functioning all the time, but seemed to be reacting to the Vertical Speed, i.e., if the VSI went negative, Autotrim commands pitch up even when within ValphaMax; when VSI recovers to positive (approx 1300fpm w GW of 65T) Autotrim gave pitch down command.
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Auto Pitch Trim Freeze High Alpha A320
Good observation Solipsis.Quite the same as what I noticed as well. Not very much in line with the books though.Also, did you check the auto trim approaching a stall in alternate law ?
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@CONFIture:
Yes I was bored and simulated the whole thing
TL at CLB detent all the time.
THS never reached the limits at all.
Other parameters unable to notice (I was flying alone).
Will try to note other parameters next time once I get to do it with a stand in PNF
Yes I was bored and simulated the whole thing
TL at CLB detent all the time.
THS never reached the limits at all.
Other parameters unable to notice (I was flying alone).
Will try to note other parameters next time once I get to do it with a stand in PNF
