Actual landing distance/ landing field lenght

[B738]

Hello,

for preflight planning the landing field lenght must be lower or equal than the landing distance available, but how is it in flight?
Can I go to an airport where the LDA is greater than the acutal landing distance but lower than the landing field lenght? How is it, when the runway is wet?

Thanks for the help!

[hetfield]

Are you talking about

- Actual Landing Distance

and

- Landing Distance Required

?

[zon3]

Hiya

According to JAR-OPS, for dispatch (planning the flight) AND in the event of in-flight replanning, your required landing distance for DRY rwy is the actual landing distance (at the expected landing weight) multiplied by 1.67
This means you must be able to stop within 60% of the available rwy length. For WET runway, add another 15% to the DRY figures. This equals about 1.92 times actual landing distance for DRY runway.

In-flight, the commander must be satisfied that a safe landing can be carried out considering the actual weight, rwy condition, weather etc.

In-flight replanning according to JAR-OPS- what does this mean? In my opinion, a change of destination. Perhaps prompted by Operations, in order to pick up stranded passengers? If anyone has a definition, please post it. Clearly, in the in-flight case there is room for interpretation. Maybe that's why we haven't been replaced by machines yet?! ;)

[vwreggie]

My opinion, if you are diverting for a non normal as dictated by the qrh then factoredlanding distances (1.67) are not applicable just the stopping distance as determined by the nature of your non normal. A diversion for commercial ie. normal ops to a rw that didn't meet the factored landing distance required would be deemed illegal in australia and I suspect elsewhere.:ok:

737 400 lims manual section 4 background information.Landing field length required by CASA must not be less ( except in an emergency) than 1.67 times the test landing distance .............

[gearpins]

ALD: Actual landing distance is demonstrated under test conditions.

Having said that, under normal conditions the variations to the test conditions in:-
1.wind 2.QNH 3.ISA dev 4.R/W slope 5. Friction coefficient of the r/w 6.a/c weight & trim 7. height over threshold 8.flare height & technique 9.speed over threshold 10.any more that I missed...
Makes us want to have some safety margin!
The people who decide these, decided that a safety margin of 40% is required for dispatch.(faa, jar, and the others).
So if an a/c under test condition took a shade less than 6000'(5987') to stop for a given wt. multiply 1.67 times gives 10000'
(1825m/3048m respectively in the metric system)

INFLIGHT conditions are generally left to the informed decision of the crew Faa insists on a minimum safety margin of 15% above what one would extract from the QRH
jar is non committal
They do not specify commercial reason or otherwise
As a pilot I would apply a margin as practical and safe as possible on a case by case basis