A320 ALT* mode
Thread Starter
Joined: Nov 2024
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From: Uzb
A320 ALT* mode
Hello! What is engagement conditions of ALT* mode? FCOM, FCTM, AFM didn’t give me the answer.. I think there is time in seconds somewhere in documents or in airbus logic from engagement ALT* to ALT/ALTCRZ mode. And how airbus compute this? Any supposes? Thanks.
Joined: Oct 2024
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From: Terra firma
This is mentioned in the FCOM. Below is the extract from the FCOM - DSC-22_30-40-50-10
“ALT* engages, when ALT is armed, and the aircraft reaches the capture zone of the altitude target. ALT* engagement is inhibited during 3 s after the selected altitude is changed on the FCU.”
Joined: Sep 2011
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From: FL390
ALT* is (loosely) based on a 0.15g demand to achieve the target altitude with some tuning in the very last part of the capture for smoothness. You can just use SUVAT equations to get what you need:
Δh=−v^2/2a
This gives you a blunt force tool to estimate your starting point, but you’ll need to use calculus to handle the final bit smoothly.
Δh=−v^2/2a
This gives you a blunt force tool to estimate your starting point, but you’ll need to use calculus to handle the final bit smoothly.
Last edited by Fursty Ferret; 15th November 2024 at 09:53.
Joined: Sep 2008
Aviation Qualifications: ATPL
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From: Scotland
ALT* is (loosely) based on a 0.15g demand to achieve the target altitude with some tuning in the very last part of the capture for smoothness. You can just use SUVAT equations to get what you need:
Δh=−v^2/2a
This gives you a blunt force tool to estimate your starting point, but you’ll need to use calculus to handle the final bit smoothly.
Δh=−v^2/2a
This gives you a blunt force tool to estimate your starting point, but you’ll need to use calculus to handle the final bit smoothly.
Spoiler
Do you have any good reference for that? Incident report, or Airbus World would be welcome? I’ve been looking for hard info inside the box for how ALT* works for ages!
