overweight landings
hello every one,
overweight landings seem a very interesting topic, judging from some threads above. i did some research into the matter & found what follows :
1) definition : overweight landing is when you land at max landingweigth + 2%.
2) certification issues for the manufacturers : A) aircraft structure must be resistent for a landing at Max Take Off Weight(MTOW) with a rate of descent of 360ft/min. B) at[ MTOW - 15min of emergency fuel ], the aircraft must meet min regulatory go-around gradients. if not, a jettisson fuel system is required.
3) for maintenance : A) landing at mlw + 2%, ok(not considered overwt as per definition). B) landing at > (mlw + 2%) & < (mlw + 5%), if soft ldg = rod <300ft/min = ok; if hard ldg = rod > 600ft/min, then inspection as per maintenance manual required. C) landing at >( mlw + 5%), then inspection required in all cases. all this info is retrievable from the on board data monitoring system in addition of faithfull techlog entries by the operating aircrew.
4) for operators & aircrew : operators need to provide their crews with overweight landing policy & technical guidelines from the manufacturer to actually perform a safe overwt landing.
here an example of such a policy:
overwt landing RECOMMENDED: -any malfunction that seriously affect airworthiness of the aircraft. - any condition where a delay in landing might be detrimental to safety. - one engine inop. - serious illness amongst crew or pax requiring immediate medecal attention. overwt ldg PERMITTED : - a malfunction not directly affecting the airworthiness of the aircraft. - an unplanned diversion. overwt ldg NOT RECOMMENDED: - complete hydraulic fail (affecting braking perfo). - tire burst/fail. - flight control troubles that adversely affect the handling of the aircraft. note: word "prohibited" is not used in this policy example.
last but not least, her some tech guidelines, once decision to land overwt is taken. e.g. for b738ng : use flap 30° for better margin to flap placard speed.
you may configure next flap as much as 20kts below normal maneuver speeds( again for increased margin to flap placard speed). burn fuel as much as possible(early gear down). long rwy, no tailwinds, or negative slopes, limit wind additives to flap placard speed, no long ldg, max reverse, use all rwy to minimise brake temp, no early turn off etc.
5) no auto lands
6) conclusion : always use common sense in dealing with such problems & if you safely can avoid them : do.
hope i did not write to many mistakes.
kind regards,
bm
Last edited by blackmail; 2nd May 2007 at 08:50.