Re: 757 Engine noise over LA

Date:         04 Jun 97 13:03:57 
From:         Tony Maddern <tmaddern@cse.unsw.edu.au>
Organization: University of New South Wales
References:   1
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Ewan Godley wrote:
>I was on a Delta Airlines flight (550) from LAX to Atlanta on the 22nd
>of December 1996 (on a 757).  As we took off from LAX with a full load,
>I could (obviously) hear the engines at near full (if not full) power.
...
>About 30 seconds after take off, as we crossed the coast line (taking
>off towards the west) both engines went suddenly very quiet. Any ideas
>what happened on the December flight?

There is a light aircraft lane running down the coast just off the end
of the west runways and if there is traffic in the lane then departing
traffic is required to stop at 2000FT (from memeory). A 757 stopping at
2000FT would require a dramatic reduction in thrust to avoid
overspeeding the flaps and a marked pitch down to stop the climb. This
gives a strong sensation of deceleration. Once clear of traffic climb
power is restored and the aircraft can climb away.
In all my departures from LAX (747-400) I never had to do this so it is
not too common but the procedure is there in the SIDs.

Tony Maddern