Simulator: predefinded routes

[Michael Kuhne]

I use predefined routes for the go-around procedures. As explained in the wiki with an altitude restriction and several waypoints (all defined in the sector file). During a simulator session I can select this route, but somehow it doesn't work (regardeless if the aircraft is on the ILS approach or at an earlier stage). I use the following line to define the go around in Geneva, runway 23:

ROUTE:GA23:PAS/7000 KEMIT GG602 SPR

If given this predefined route most aircraft just proceed to SPR (not always the closest point) and disregard the altitude restriction. If on the other hand I copy-paste the route into the respective field all aircraft follow it including the altitude restriction.

 

Anybody an idea why this is not working? What am I doing wrong?

[Eric Bocaneanu 906549]

The algorithm to find the closest point on predefined routes is the following: a perpendicular line is drawn to the closest leg of the route from the aircraft, then the aircraft will proceed to the next waypoint on that segment. Without a screenshot of what's happening I can't tell if what is going on there is the intended action or not.

[Michael Pike]

Ah. That explains why I can't get a pre defined route for visual circuits to work. Thanks Eric. I'm using dummy waypoints to define the circuit and with that information I may get on a bit better. Actually, this must be a common requirement. Has anybody got any clues to make it work for a general visual circuit for light aircraft? Where would you put the waypoints?

[Eric Bocaneanu 906549]

From what I remembered from what I discussed with the developer the solution is the following:

 

We discussed that adding an initial point just at the end or at the start of the RWY will work as the closest segment will be the one along the RWY heading.

 

I have not tested it yet however. Any feedback on this is welcome.

[Michael Pike]

I have experimented a bit with this. First thing I realised is you can't put the whole circuit in a predefined route. Because the aircraft at the start will already be at the end. So I use two routes; the first, for use on the runway, gets the plane onto the downwind. Then when you report downwind, you use the second route to turn base and final. However this doesn't work as expected. It seems that an aircraft already following a predefined route skips an extra waypoint when [Mod - Happy Thoughts]igned another route. If I put an aircraft onto a downwind heading I can [Mod - Happy Thoughts]ign a route which it will intercept as expected, continue downwind to the base turn etc. But if it's status is "following route" downwind, it will always skip the base turn and go directly to the waypoint at the end of the base leg, even though the downwind leg must be the closest one by the algorithm you described. (No simulated controllers in use!)

 

Further questions about the algorithm: do you know what happens if all the legs are in front of the aircraft? So there are no legs where you can draw a 90 degree line.

 

A related problem I have found with light aircraft is the anticipation of the turning point at low speed. The P28A by default does 67 kts around the circuit, yet it turns about 1.5 nm before reaching each waypoint, the same as a jet doing 250 kts or more on an airway would do. This means I have to experiment with extra waypoints to produce a result that looks realistic. Could I request that in a future version, the turn should commence about 1 radius of the turn before a waypoint at current speed instead of a fixed distance?

 

At the moment (current release version 3.2), I have to add 1nm to the point where I want the aircraft to turn since its turn has a radius of about 0.5 nm. This means I can't use the same waypoints to go the other way round the same circuit - one set for 27 lefthand and another, offset the other way, for 09 righthand. It makes for a lot of trial and error and editing the sector file to get a satisfactory result.

[Gergely Csernak]

Further questions about the algorithm: do you know what happens if all the legs are in front of the aircraft? So there are no legs where you can draw a 90 degree line.

Normally it should select the first point and direct to that.

 

A related problem I have found with light aircraft is the anticipation of the turning point at low speed. The P28A by default does 67 kts around the circuit, yet it turns about 1.5 nm before reaching each waypoint, the same as a jet doing 250 kts or more on an airway would do. This means I have to experiment with extra waypoints to produce a result that looks realistic. Could I request that in a future version, the turn should commence about 1 radius of the turn before a waypoint at current speed instead of a fixed distance?

 

At the moment (current release version 3.2), I have to add 1nm to the point where I want the aircraft to turn since its turn has a radius of about 0.5 nm. This means I can't use the same waypoints to go the other way round the same circuit - one set for 27 lefthand and another, offset the other way, for 09 righthand. It makes for a lot of trial and error and editing the sector file to get a satisfactory result.

I will check the turning simulation.