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Old 24th Apr 2002, 11:52
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OverRun
Prof. Airport Engineer
 
Join Date: Oct 2000
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Rosscoe,

UPDATED WITH MORE TAKEOFF DATA 25/04/02

Your TORA/TODA numbers for Hamilton Island show it is a bit of a problem because the takeoff/approach gradients are 1.71% and 2.07% respectively.

This reduces the effective length for takeoff, which (although calculated by performance engineers from the type A chart and all sorts of electronic wizardry) is effecively a couple of hundred metres shorter than the published TODA. The worst case is RWY32 STODA which drops to 1510m at 1.9% takeoff gradient and less at 1.6%, but you've got 1754m STODA at 1.6% on runway 14.

The takeoff temperature is an issue. I'm guessing it's warmer there than you said. Winter flights (for the Melbourne crowds) could be 30 deg C, summer could be 34 deg C (unless you fly late in the evening).

Takeoff weight also depends on destination. For Hamilton Island, its gotta be MEL, which is 1058 nautical miles. Add in some pax (say 90% of the 156 seats in the ex-AA planes - these airlines always want to fly SO fullll), say 9559kg fuel including reserves and 1300kg for thunderstorms in MEL (as ops will expect to include), and excluding any freight, and using the Qantas aircraft empty weights and engines, means a takeoff weight of 65907 kgs. Heavy !!!!! Your PCN is fine, but your runway is short.

The 737-800s will get out at a better angle than the -300/-400 series and carry out all their flab (6-7 tonnes extra due to the bigger wing) and get rolling a bit quicker (more grunt). The big wing also gets them off at a lower speed (proportionately to weight).

The actual performance depends on the motor, and here is some of the confusion. VB are running the 24,200lb or 26,300 lb motors depend on who you listen to. I reckon its the 26,300lb motor derated wherever possible. QF brought aircraft with the 27,300 lb motor, but they've got them registered as 24,200lb

Do-able at Hamilton Island? I'm not sure. Depends on wind, acceptable penalties in terms of pax weight limits, etc. If you had had 1800m-1900m with a 1.6% takeoff gradient - you've got a good chance and a pretty healthy business case. At your numbers though, it's getting marginal, and any tech stop at Brisbane for gas will bug*er the economics. You've maybe gotta get a bit creative with a package to get a 737-800 operation in there.

The raw numbers are:
27,300 lb motor= 1585m takeoff at 65,907kg, at 30 deg C, nil wind, sea level, aircon packs off, dry runway
26,300 lb motor= 1645m at 30 deg C ditto ditto
[26,300 lb motor= 1675m at a cooler day of 25 deg C just to see the impact of temperature, ditto ditto - not much change there]
24,200 lb motor= 1770m at 30 deg C, ditto ditto

PS - VB ops are more conservative than QF so there's no relief there :wink:

Last edited by OverRun; 25th Apr 2002 at 03:14.
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