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Landing Field Length in FMS

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Landing Field Length in FMS

Old 26th Jun 2013, 18:54
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Landing Field Length in FMS

Hi Folks
one quick question that has been bugging me for the last couple of days.
the LFL shown in the FMS PERF page, i use a Collins FMS6000 on the 605, is it the ALD factorized by 1.67?
if so will i get a message if the LFL is longer than 60% of the LDA - LDR - ?

also for the wizzards out there, what kind of vertical clearance do you obtain when manually entering an obstacle in the TAKEOFF REF PERF pages - 35ft?

Many thanks also because i am aware that are very specific questions but i can not find an answer from the manual!
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Old 26th Jun 2013, 21:13
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Not sure of your FMS version, but this is the criteria:

From the end of runway, the obstacle clearance surface begins at 35' above, with a 40:1 slope origin, or 152'/nm.

The aircraft climb gradient minimum is 200'/nm, the difference is the required minimum clearance. These surfaces go out to 10nm from runway end (1500' ROC).

As an example, right at the end of runway, you have 35' of clearance.

At 1nm, you have 48' ROC, at 2nm you have 96' ROC.

Depending on your FMS, there are certain 'nuances' built in with the ROC for ARR and DEP....(and perhaps in your situation, the Collins box does have certain unexplained differences in the programming)

Edit: this is aircraft variant specific as well...

Last edited by FlightPathOBN; 26th Jun 2013 at 21:33.
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Old 26th Jun 2013, 21:57
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baobab72

the LFL shown in the FMS PERF page, i use a Collins FMS6000 on the 605, is it the ALD factorized by 1.67?
Be very careful of using FMS data as the sole means to determine Landing Performance. Generally speaking, FMS databases like the FMS6000 do NOT respect "declared distances" and it is possible to inadvertently exceed max landing weight for a specific runway.

This FAA video addresses Declared Distances, aeronautical charts and FMS databases.


what kind of vertical clearance do you obtain when manually entering an obstacle in the TAKEOFF REF PERF pages - 35ft?
The best practice for calculation of max takeoff weight as well as development of One Eng Inop contingency routes is to engage the services of a professional performance engineering company like Jeppesen OpsData or Aircraft Performance Group. The FMS in the CL605 is not suited to that purpose.

This FAA video should help clear up the abundant misunderstandings on the subject.

Also see AC 120-91 and links presented on this NBAA page.
Zeffy is offline  
Old 26th Jun 2013, 22:06
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Zeffy,

Great points!

although I would not necessarily put "best " and "Jeppesen OpsData or Aircraft Performance Group." in the same reference...

I would gather that the Boeing people may not have the 'best' information for other aircraft or FMS issues...

OEI performance is very, very, repeat, very specific to the ac variant, engines, and local conditions.....
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