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GAJ52

FMC Waypoint Question

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Is there any way to force the FMC to overfly a waypoint entered into the Route page. I know when ammending a Sid or Star you can use the 'Overfly' command, but how do you do it when entering waypoints manually into the Route page.Glen


Glen Coyne
 

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Set your HDG to the inbound course to the fix, fly MCP HDG mode until past the fix... maybe I missed the question. Depending on what you're trying to do (you didn't mention that) you could create another fix 2nm from the fix you want to overfly, which would give you about the same result.


Dan Downs KCRP

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"Is there any way to force the FMC to overfly a waypoint entered into the Route page."Boeing FMC's do not allow an overfly for a regular waypointCheers.Q>

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Sorry I should have explained what I was trying to do.I noticed on the WILLO4C Star into London Gatwick the author on the star did not put an overfly command at HOLLY at required in the Star, before a sweeping left turn to WILLO to begin a holding pattern. The aircraft turns too early to WILLO missing out HOLLY. As an experiment I thought I would try entering the Star manually but it did exactly as before and turned before HOLLY.I'm using the 737-800 BTW, not sure if the 747-400 may be a bit more sophisticated.Glen


Glen Coyne
 

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I think I see what you're trying to do Glen.. how early is the aircraft turning? As said before.. add a couple of other waypoints on the STAR to try to force a more accurate follow of the STAR.. other than that perhaps the star programme for the FMC could be improved?CheersCraig


Craig Read, EGLL

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Craig,It starts turning approximatly abeam WILLO which is totally the wrong intercept heading to commence the holding pattern. I appreciate there are ways around the problem, I am just surprised there is no way to force the FMC to overfly a fix, like putting a small plus sign or something similar before the fix name.I have since ammended the Star by adding the Overfly command to HOLLY, haven't tried it yet though.Glen


Glen Coyne
 

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Terry Yingling at planepath.com has a thread in the Terminal Procedures on this issue. He is aware of it and plans to have it resolved by the next cycle. Meanwhile, adding the keyword OVERFLY in the sidstar file will fix it... open the file, search for FIX HOLLY and change it to FIX OVERFLY HOLLY (if you haven't already).I always like to recommend that any issue with a sidstar procedure be brought to the attention of the author. They will usually like the feedback.


Dan Downs KCRP

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As the FMC do not allow an entry of the overfly command, you may also try to cheat a little to get the desired effect while you are in flight. You do this by entering an ATW (Along Track Waypoint) in the FMC very close to the waypoint in question.Downselect HOLLY to the scratchpad, then enter HOLLY/0.1, then click on HOLLY again. This will create a waypoint 0.1NM after HOLLY and will force the aircraft to wait with the turn. You can also try HOLLY/-0.1, then the new wp will be created just before HOLLY.Bear in mind that I'm not familiar with this exact procedure at Gatwick, so you may try with other settings to get the desired effect.

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Guest tomahawk_pa38

On a slightly different matter, when listening in on the scanner I often hear ATC telling an aircraft to 'descend flight level XX0 to be level 10 before XXX@ how does this get actioned in the real world please ? Do you create a new waypoint as shown above ie HOLLY/10 and put an altitude constraint by it or is it done some other way ?

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This is a normal ATC request, usually to put you into approach airspace vertically before they hand you off. Your guess is correct, enter a fix distance before and add an altitude constraint. the form is FFF/-nn where the minus sign is used if the fix is before FFF.


Dan Downs KCRP

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