Old 25th Feb 2019, 22:09
  #27 (permalink)  
HPSOV L
 
Join Date: Mar 2006
Location: expat
Posts: 115
It's a good subject Cropduster, and inevitably generates opposing opinions because there is truth on both sides.

I wonder if you are extending your companies guidance beyond it's original intent, which seems to relate to non-time critical problems (such as flaps)?
The ETOPs thing comes up quite a bit and it is true; engine reliability is such that you could argue that the balance of risk favours increasing the flight time rather than accepting the reduced margin for safety in a high energy landing. However it's not that simple:
I can think of a couple of cases off the top of my head where the "good" engine was discovered to have a problem on landing (eg LOT 787 diversion to JFK recently).
A properly planned overweight landing uses far less energy than the one in spectacular RTO certification videos as you have at least twice the available stopping distance and a thrust reverser. The brake fuses will probably deflate the tires but that is accepted as part of the aircraft design.
Jettisoning fuel may be problematic in environmentally sensitive areas. If you don't want to fly off to a remote designated fuel jettison area, you may have to invoke emergency authority. Which is fine but could you justify that if the performance was adequate to safely land overweight?
Boeing designed the thing to land above MLW in emergencies. FAR regs do not even require it to have a jettison system.

Having said all that, my philosophy is that if circumstances permit I will start fuel jettison as soon as possible and then do an unhurried set up for landing. I'll figure out the maximum acceptable landing weight during this time using a nice fat margin. The resulting landing may or may not be overweight.
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