It's yours, and it's free: FMS Question and Answer...
Join Date: Aug 2002
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@karaoke
negativ
@traffic
correct. The FMC will force the autopilot to smoothly intercept the direct track between waypoint a and b, if not programmed to fly-over a, and then intercept the applicable track. This is not a big deal, if the track differs by only for example 20 degrees. However, if for instance the inbound to a is 90 and the track from a to b ist 180, the aircraft will normally turn quite early.
There are a lot of SIDs with fly-over wpts, they are underlined in our charts, and the fmc is programmed accordingly.
But once again! If you want us to fly over a specific fix, please tell us. Otherwise we will pass by!
To make it clear: If you clear us via pam to arnem, the a/c will track to pam initially, and then (before pam) initiate a turn to intercept the direct pam-arnem track.
In the 90 degree turn example the a/c will start the turn about 6.3 NM before the fix with 25 bank and a gs of 450kts. With half-bank mode about 12NM before the first fix.
negativ
@traffic
correct. The FMC will force the autopilot to smoothly intercept the direct track between waypoint a and b, if not programmed to fly-over a, and then intercept the applicable track. This is not a big deal, if the track differs by only for example 20 degrees. However, if for instance the inbound to a is 90 and the track from a to b ist 180, the aircraft will normally turn quite early.
There are a lot of SIDs with fly-over wpts, they are underlined in our charts, and the fmc is programmed accordingly.
But once again! If you want us to fly over a specific fix, please tell us. Otherwise we will pass by!
To make it clear: If you clear us via pam to arnem, the a/c will track to pam initially, and then (before pam) initiate a turn to intercept the direct pam-arnem track.
In the 90 degree turn example the a/c will start the turn about 6.3 NM before the fix with 25 bank and a gs of 450kts. With half-bank mode about 12NM before the first fix.
Last edited by crj-jockey; 31st Aug 2002 at 23:57.
Pardoned PPRuNer
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To make it clear: If you clear us via pam to arnem, the a/c will track to pam initially, and then (before pam) initiate a turn to intercept the direct pam-arnem track.
NO TRACK SHORTENING
Only kidding
Join Date: Jul 2001
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Spearing;
Yes we have seen the busses go outside of the airway...
Oh, for any other responses. I will be at our convention for the next week in Cleveland... Back in a week...
regards
Yes we have seen the busses go outside of the airway...
Oh, for any other responses. I will be at our convention for the next week in Cleveland... Back in a week...
regards
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Join Date: Apr 2001
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A quick post to (a) bring this back into circulation (because I'm sure we haven't finished discussions just yet); and (b) answer the 'fly-over'/'fly-by' point.
It is a basic 'rule' of instrument flying - given in CAP54 Apendix M if memory serves, if not, please correct me - that a pilot may 'anticipate' the turn overhead a beacon or waypoint, provided that the aircraft remains within the protection of controlled airspace. For this reason, controllers should not be surprised that the aircraft turns early.
In the FMC database, a few points on some routes (especially SIDs and STARs) are defined as 'fly over', others, as 'fly-by'. In the Boeing, there is no facility to make a waypoint a 'fly-over' one.
I must say, that if separation depends upon it (miss distance predicted at 10nm or less, say), I would hope to be on a heading or series of headings, rather than trusting my safety to the aircraft's tracking.
One infuriating thing about the Spanish is their unwillingness to use headings, and just a couple of days ago, I found myself 6nm from opposite direction traffic, both of us on our 'own nav', in the upper air!
One final point for the high-paid help: There is no phraseology for instructing a pilot to 'fly-over' a waypoint, the phraseology laid down does not make a distinction between fly-by and fly-over.
It is a basic 'rule' of instrument flying - given in CAP54 Apendix M if memory serves, if not, please correct me - that a pilot may 'anticipate' the turn overhead a beacon or waypoint, provided that the aircraft remains within the protection of controlled airspace. For this reason, controllers should not be surprised that the aircraft turns early.
In the FMC database, a few points on some routes (especially SIDs and STARs) are defined as 'fly over', others, as 'fly-by'. In the Boeing, there is no facility to make a waypoint a 'fly-over' one.
I must say, that if separation depends upon it (miss distance predicted at 10nm or less, say), I would hope to be on a heading or series of headings, rather than trusting my safety to the aircraft's tracking.
One infuriating thing about the Spanish is their unwillingness to use headings, and just a couple of days ago, I found myself 6nm from opposite direction traffic, both of us on our 'own nav', in the upper air!
One final point for the high-paid help: There is no phraseology for instructing a pilot to 'fly-over' a waypoint, the phraseology laid down does not make a distinction between fly-by and fly-over.
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Traffic Traffic
"Thanks for the info, I have of course in the meantime figured out how to stop the problem in the future -
"NO TRACK SHORTENING"
I know your tongue was in your cheek, but even without track shortening, the Airbus will turn early in order to intercept the next track - we never fly over any waypoints unless the outbound track is the same as the inbound, or we tell it to. Of course, then we turn "late" and probably approach the other side of the airway.
"Thanks for the info, I have of course in the meantime figured out how to stop the problem in the future -
"NO TRACK SHORTENING"
I know your tongue was in your cheek, but even without track shortening, the Airbus will turn early in order to intercept the next track - we never fly over any waypoints unless the outbound track is the same as the inbound, or we tell it to. Of course, then we turn "late" and probably approach the other side of the airway.
Northern sky
To make it a flyover point rather then a flyby, I develop a WP over the point. If ABC is a flyby, try ABC/-0 in the scratchpad and drag it up to the original ABC. Your mileage may vary.
To make it a flyover point rather then a flyby, I develop a WP over the point. If ABC is a flyby, try ABC/-0 in the scratchpad and drag it up to the original ABC. Your mileage may vary.
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Going back to the question re. the A330 descent profile - as already pointed out by Spearing Britney, the profile is worked out in advance by the FMGEC using various factors. The difference is between A320/1 and A330 - the A330 will, if you let it, compute an incredibly efficient (but slow) descent profile, despite calculating a perfectly normal climb and cruise. This is not a problem on A320/1 because the speeds are faster, but can be on the A330. We tend to modify the descent speeds to something more realistic - usually about .81/310knots. If you don't do this - the machine will use approx .79/280 knots - again dependent on cost index etc. She does come down slow, and she sure don't like slowing down!!! 160 kt to 4 miles is the absolute maximum you can do, if you want to be stabilised at 800-900 feet.
Great areoplane though!!
Great areoplane though!!
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West Coast,
Do you claim this works on the 737? -EFIS or -NG?
I've never seen it done or tried it. I'll give it a go next week.
I guess that the theory goes that in attempting to track from ABC/-0 to ABC, the aircraft flies over the waypoints. It's a nice idea.
Do you claim this works on the 737? -EFIS or -NG?
I've never seen it done or tried it. I'll give it a go next week.
I guess that the theory goes that in attempting to track from ABC/-0 to ABC, the aircraft flies over the waypoints. It's a nice idea.
