Landing Field Length in FMS
Thread Starter
Joined: Jul 2010
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From: france
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!
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!
Joined: Mar 2011
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From: engineer at large
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...
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 June 2013 at 20:33.
Joined: Feb 2006
Aviation Qualifications: ATPL
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From: USA
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?
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?
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.
Joined: Mar 2011
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From: engineer at large
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.....
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.....
