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Old 29th Dec 2012, 06:03
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noneya
 
Join Date: Jul 2005
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Landing Distances are not calculated with thrust reversers deployed. The figures only takes into account, landing in the touchdown zone, max anti-skid braking, and ground spoilers deployed.

There is an exception in some aircraft such as the G550 that when landing on a wet runway, the wet landing distances numbers do incorporate TR's.

To be more specific if you care, below is the information right out of the G450 OM. But is basically the same across all aircraft I have flown.

Landing Field Length

The landind distance shall be the horizontal distance required to land and come to a complete stop from a point at a height of 50 feet above the landing surface. Landing distances are shown as a function of flap position, anti-skid functions (operative or inoperative), landing gross weight, airport pressure altitude, wind condition, spoiler deployment (automatic or manual), and possible speed increase (delta V) to the threshold speed (Vref). The threshold speed increase (delta V) correction grid provides landing distance increments which would occur on occasions such as Category II approaches or when the pilot elects to use autothrottle all the way to touchdown.

Normal Flap Landings:
Conditions:

The following conditions apply for normal flap landings:
1. All engines operating at high idle before touchdown (high idle automatically established with gear down, flaps 39) and reduced automatically to ground idle about 5 seconds after touchdown.

2. Flaps 39 and gear down.

3. Landing distances based on 3.0 glide path at 50 feet and 6 FPS sink rate at touchdown.

4 Distances are shown for both anti-skid operative and inoperative. Either ground spoilers armed and automatically deployed on touchdown, or manual speed brakes selected after touchdown. For a complete ground spoiler / manual speed brakes deployment failure, a correction factor is presented at the top of the anti-skip operative chart.

So as you can see, no where is Thrust Reversers factored into landing distances.

Hope this helps in some small way
J
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