landing perfomance
 

Just a quick question, we're trying to remember exactly which figure you use on a Jeppesen plate for your landing distance. Anybody recently done Perf A? What is the definitrion of LDA? Is it from the glide slope or are you allowed to use the total length.
Thanks in advance for any input.

From Jeppesen introduction:

LANDING DISTANCE AVAILABLE (LDA) (ICAO)

The lenght of runway which is declared available and suitable for the ground run of an airplane landing.

lets have a look at Amsterdam (Schiphol)

RWY LDA RWY
01L 9350 10827
19R ------ 10827
01R 9268 11155
19L 9268 11155
06 10663 11483
24 -------- 11483


The landing distance is from the threshold or displaced threshold to runway end.

Amsterdam has displaced the threshold of rwy 01L, 06 and 19L.

Note that LDA of rwy 01R is not the same as the rwy length and it does not have a displaced threshold. This is due to (as the note says) "For normal operations LDA 9268 ft. In exceptional cases the additional pavement of sufficient strength of 1887 ft beyond the red rwy lights is availble on request"


so LDA is from (displaced) threshold GREEN CROSS LIGHTS to the runway end RED CROSS LIGHTS.


Hope this helps.

Or, to put it more simply...
 

LDA = RWY length minus dist to THR (or displ THR)

Hobbit,

You use the Distance Beyond THRESHOLD not GLIDESLOPE as air-distance ie. approx 300m from threshold, has already been catered for in the LDA calc.

Hope this helps.

SR

PS: If you fly Boeing, the Advisory Info in the QRH for Landing Distances are also from threshold with air-distance accounted for.