Re: Question: Fuel Dumping

Date:         15 Jan 97 04:23:57 
From:         Pete Finlay <pete@meads.demon.co.uk>
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In article <airliners.1997.80@ohare.Chicago.COM>, michael.f.lechnar@boei
ng.boeing.com writes

<<other stuff snipped>>
>
>The main reason that fuel jettison is used is to meet the FAR 25 requirements
>for approach climb and landing climb gradients.  A side benefit to landing at
>a lower weight is less stress on the airframe.

Well, you're *nearly* right, but not quite. The main reason for dumping
fuel is for us to get the aircraft down below max. landing weight as
soon as possible. Secondary to this is that the lower the weight, the
lower the approach speed, which is important in landing with flap/slat
malfunctions.

You've got to bear in mind that nearly all big airliners take-off at a
much higher weight than they can land at. Therefore, if you have to land
earlier than scheduled, due an en-route diversion, or an emergency after
take-off, you invariably need to dump fuel down to below landing weight.

AFAIK, the 'approach climb', and 'landing climb' don't enter into it
(whatever they are)

--
Pete Finlay
pete@meads.demon.co.uk
Boeing 747 Senior Flight Engineer