737 Perf. inflight Actual LDG distance

[In dis-sky's]

Hi all, a quick question regarding the 737 Performance inflight Actual LDG distance table:

The table lists corrections for 'No reverser' and '1 reverser'.
Now I understand why this is the case with MAX MANUAL braking, but why does it list corrections for different autobrake settings as the autobrakes provide a decelleration RATE. ie they apply less brake pressure when you use reverse thrust.

Thanks

[OPEN DES]

For the same reason as in an Airbus. The reversers help in the deceleration once the aircraft starts braking: they help in achieving the selected deceleration-rate by the autobrake. Once the selected deceleration-rate is attained the reversers have no further effect on deceleration.
In other words: it takes time for the autobrakes to deliver the required brakepressure and achieve the decel rate, up to the point where the selected deceleration is attained the reversers have a cumulative effect.

[In dis-sky's]

Thanks OPEN DES for your reply. Still, why is the correction higher with a lower autobrake setting. You would expect the deceleration rate to be achieved sooner with a lower a/b setting, and thus a smaller correction to the landing distance.

Thanks IGh. Very interesting reading.

[OPEN DES]

Hello I-d-s.

I am no expert whatsoever...

But it would help if you could show us the data itself and the corrections to be applied. Are they expressed as a % of the distance or as an absolute corrections in meters?

Cheers