PPRuNe Forums - A320 ALERT HEIGHT : from theory to practice

PPRuNe Forums (https://www.pprune.org/)

- Tech Log (https://www.pprune.org/tech-log-15/)

- - A320 ALERT HEIGHT : from theory to practice (https://www.pprune.org/tech-log/604091-a320-alert-height-theory-practice.html)

Quote:

Originally Posted by mcdhu (Post 10017708)

Have a look at the diagram called "Failures and Associated Actions Below 1000' for Cat111 Approach without DH" in PRO-NOR-SRP-01-70 which makes it clear that from 200'RA to 100'RA you will GA for Triple Clicks, Amber Caution, Eng Fail, Alpha Floor, AP OFF and/or the Autoland Warning Light (unless visual). From AH (100'RA in the minibus) you will only GA for the Big Red Light. You will still hear triple clicks and single chimes, but you can ignore them.
This calls for a mind set change at AH and careful briefing.
I'm sorry I don't have the nouse to be able to post a pic of the diagram - perhaps someone cleverer than me will.....

Mcdhu I had look at the diagram you are referring to and when seen carefully , it would imply that you are not to expect any triple click below AH (100ft RA) . If you look carefully the big arrow with the list of failures , one of which is the reversion (triple click) belongs to , it overlaps the red warning light failure at the 100 ft point and above . By the way since you mention it , are we allowed to attach here material from manufacturers manuals ?

From the FCOM

Quote:

Below 100 ft (radio altimeter), the FMGS freezes the landing capability until LAND mode is disengaged or both APs are off.
Therefore a failure occurring below 100 ft does not change the category of the system

Yup, all agreed. You should not hear a triple click below 100'RA and single chimes can be ignored.
All we are going around for below AH is the Red Autoland Warning Light which, if accompanied by a Cavalry Charge, requires a manually flown GA - "GA Flaps", TOGA and pitch to 15 degrees NU (assuming 2 engines).
Interesting discussion gents - thanks.
Somebody asked if we can post extracts from FCOM etc - I don't know, but some folks do it - I just don't have the know-how.

Yes exactly, a triple click below 100ft RA would have contradicted the whole essence of having the AH in the first place .

AH Minibus 100 feet
A330/A340 200 feet

Below Alert height as people have said you would only go around for a red auto land light. If the cavalry alert comes on then you need to manually fly the go around or if you hit the ground when you go around then the autopilot will trip out due to TOGA+Ground condition sensed.
You would get a single chime below alert height if you had an engine failure for example and the capability on the FMA would downgrade but no triple click and you don't need to go around as you are below alert height and no red auto land light.

Quote:

You would get a single chime below alert height if you had an engine failure for example and the capability on the FMA would downgrade

You don't get FMA change below Alert height for a single failure. That's why there is an Alert Height.