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Additional FMC constraints error

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Hello everyone!

Is the behaviour shown on the movie reproducable on all machines?

If I add entire STAR RIPAM 3L it includes speed constraint at RIPAM. But if I already have a route to RIPAM, then adding STAR I do not have a speed constraint. If I try to add it manually I have an error with loss of functionality of left select key.

What is wrong here? Have not noticed it before...

Haven't tried it yet, but I see only the way is to plan the route until the point before RIPAM. So the last route point is not the first STAR point.




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yes, this sounds familiar - it is quite the logical challenge to determine what part of a procedure a waypoint belongs to when one procedure joins the other one.

In this case the problem is that we do not allow (yet) assigning a restriction to the enroute part. So if you enter the enroute first, RIPAM is considered part of it and the FMC will attach the rest of the STAR after RIPAM. And you can´t enter the restriction now, because RIPAM is part of the enroute section, not the STAR.

This whole thing is very complex from a procedural point of view - I never thought about it when flying the aircraft.

But it gets even worse - lets say we allow changing the restriction at RIPAM - but now you enter the STAR again. What should we do? Keep the restriction you entered, or overwrite it again with the "official" restriction?

The real FMGS in the Airbus I fly now has a similiar problem. If you enter a cruising altitude that is below the restrictions on the STAR, it will erase those restrictions. But if you later decide to fly at a higher cruising level again, the restrictions are still gone and you might bust them if you don´t check your charts carefully...

So yeah, the old rule applies: Fly the airplane where you need it to go, don´t rely on the FMS to do it for you.

Cheers, Jan


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Jan, thank you for a good answer (as usual)!)

It was an interesting example from Airbus.

If I got you correct a real 737 does allow to change constraints for cruise waypoints. If yes, are you going to get it closer to reality with our model?

Once again: I've got not a critical issue with this and I always try to fly the plane with my head. But it is always good if you have a kind of backup solution ;)

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