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Old 25th Jun 2010, 07:15
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John Citizen
 
Join Date: Aug 2003
Location: Melbourne
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Airbus (A320) engine out target speed/SRS after takeoff

I am a bit confused understanding the SRS (engine out) and V2.

For an engine failure after takeoff, the FCOM says
After lift-off, follow the Speed Reference System (SRS).
I always thought that if you follow the SRS as per FCOM, then this will give you V2 speed (if engine out).

In Australia, for our proficiency (CAO's) we are supposed to maintain :
Asymmetric flight tolerances (aeroplanes):
(b) indicated airspeed:
(i) initial climb — nominated 1 engine inoperative climb speeds
+ 5, - 0 knots;
This means maintain V2, +5, -0. I heard someone actually failed a proficiency test because they were outside these limits.

The takeoff performance preamble says
Second Segment - V2 speed (constant KIAS).
Therefore you can conclude that you should fly at V2 (as close as you can) following an engine failure on takeoff.

Here are some quotes from the FCOM which confuse me :

In SRS mode, the aircraft maintains a speed target equal to V2 + 10 knots in normal engine configuration. When the FMGS detects an engine failure, the speed target becomes the highest of V2 or current speed, limited by V2 + 15 knots.
Therefore if you experience an engine failure airborne at V2 + 10, will the SRS now guide you to fly at V2 + 10 instead of V2 ?

Engine Out :

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.
Does this mean that the SRS does not always guide you fly V2 speed ?
Does this mean the SRS will guide you anywhere between V2 and V2 + 15 speed ?

How are we supposed to fly at V2 speed as required by the performance preamble and by the authority for our proficiency if the SRS will not guide us to do so ?

Do we now deliberately ignore the SRS (contrary to FCOM) and set an attitude on raw data to give us V2 speed ?

Or do we follow the SRS and fly at up to V2 +15 speed, contrary to performance preamble and proficiency requirements ?

Or do I just have no idea
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