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SRS ( speed reference system ) ???

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SRS ( speed reference system ) ???

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Old 25th Sep 2009, 10:36
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SRS ( speed reference system ) ???

First off i'd like to apologize for asking too many questions i hope no one is getting annoying ( the reason why i keep posting questions is because im reading through chapter 22 in the A320 Maintanence manual and i always get stuck and come up with a couple of questions ).
Anyways my question is :
what is SRS ( all i know is that its a mode that guides the aircraft along the pitch axis to obtain a reference airspeed ( V2+10 ) at take off phase ).
but i dont quite understand the definition and the purpose of this system
i'd really appreciate it if someone can explain it to me in a brief reply
thanks in advance and sorry for asking alot once again
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Old 25th Sep 2009, 12:24
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You've got it. That's all there is to it. It keeps you at V2 + 10 at takeoff (unless you have an engine failure, in which case you're limited either to your current speed provided it's below V2+15, or V2, whichever is higher).

SRS guidance means your initial climb is performed at a safe speed in case of engine failure. In such an emergency, it also means that the aircraft is guaranteed (!) a minimum vertical speed of +125fpm. It also provides attitude protection to avoid nose-up effect during the takeoff, which could be very dangerous. (it limits to 18degrees or 22.5 degrees if there's windshear.)

1234
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Old 25th Sep 2009, 12:37
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so it adjusts the pitch (reduces it accordingly ) in order to obtain V2+10 at take off ... ok i get it now
but why V2 + 10 in specific though? why not using V2 only ? i read somewhere that ''V2'' has to be maintained untill the acceleration altitude . and now this system states that V2 + 10 has to be maintained :S how come ?
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Old 25th Sep 2009, 13:00
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This may so obvious as to be wrong, but it gives you an albeit small cushion - V2 is really the bare minimum - and one needs as much as one can get in the case of an engine failure or any kind of master caution on takeoff.

And your rule about V2 is nonsense. Unless you remember it incorrectly - you need always to be at or above V2 once airborne - it is after all "takeoff safety speed".

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Old 25th Sep 2009, 13:10
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Thank you very much i understand now
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Old 25th Sep 2009, 14:37
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Absolute pleasure. Someone happy in pprune - I thought I'd never see it.



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