A320 Angle of bank
 

what function/computer control the AOB of the A320 and why
Single engine >>>AOB reduced to 15 degree
any ref in FCOM?

Hi,

I found it in the LPC Browser (the new Electronics FCOMs from Airbus), but the table of contents is written in a different way:

REF 22-20-60-50 (Auto Flight - Flight Management - Other Functions - Engine Out), it says:

"In the speed reference system (SRS) mode, the takeoff speed target is V2, or the current speed if it is higher but no more than V2 + ​15. The magenta triangle indicates V2 in all cases. The GO Around speed target is VAPP, or the current speed if higher, limited to VLS + ​15 kt.


The system limits autopilot (AP) and flight director (FD) bank angles during takeoff and approach phases as follows :

* ​15 ° when the aircraft speed is below the maneuvering speeds (F, S, or Green Dot speed) ​-10 kt

* Then linear increase to ​25 ° up to maneuvering speeds (F, S, or Green Dot speed) ​-3 kt

* ​25 ° above maneuvering speeds (F, S, or Green Dot speed) ​-3 kt.
Note:

The engine-out bank angle limits apply, when the FG part of the FMGS has detected an engine-out. It cannot be cleared by the crew through the MCDU E.O CLEAR prompt."

I haven't found the equivalent reference in FCOM, but will keep looking and post here again.

Actually found the FCOM reference too:

FCOM 4.04.30, OTHER FUNCTIONS, Engine Out, Flight Guidance part.

Thank you. I did not realized that it will be in FCOM 4 :D

This thread opens a new question to me: Which bank limit do I have during an ordinary approach flying Vapp? I cannot find anything about that in our OMB, FCTM, etc...

DSC-22_30-40 Speed/Mach Control:
".... as long as the speed target is managed, the FMGS limits the aircraft to the maneuvering speed of the current slats/flaps configuration (VAPP, F, S, Green Dot)."
You can use 30 degs bank with managed speeds.

Redfly
From an Airbus presentation quoted below:

Maneuvering capability

• At V2, one engine out: Stabilized turn at 30°bank before alpha max
• At V2 + 10, all engines operative: turn at 40°before alpha floor
• At Green Dot: Stabilized turn at 45°bank before alpha prot

At Vls (final takeoff up to landing) : Stabilized turn 40°bank before alpha floor

Which brings along a point it is worth remembering..

Flap 3 departure. You reach 2 eng accel alt.. You are now just past F speed, Flap 1 selected....Now well below S speed in config 1+F. Engine fails.

Two things worth remembering. If you select a heading to get away from a mountain, you will get max 15deg AOB. Secondly if you now select TOGA, you will get SRS!

But it will be GA SRS.

That 15 degree limitation most likely has to do with requirements for single engine takeoff obstacle clearance that limits bank to 15 degrees below 400'.