mtr75

ATC question - IFR approaches

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This might be a bit involved for a flight sim topic, but I've noticed that the stock ATC for P3D will give you inappropriate altitude assignments on IFR approaches. The thing I see it do regularly is assigning an altitude below the MSA (minimum safe/sector altitude) on an approach, and/or assigning an altitude below that specified in the approach plate. At my home airport it regularly gives me an altitude assignment 800 feet below what is specified on the approach plate at the IAF.

I wondered if using an ATC addon might help with these types of problems, but the programs are expensive. Any thoughts, comments, ideas?

Thanks!

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As for the MSA altitude, someone can correct me if I'm wrong but that altitude is hard-coded into P3D for a certain section in the sim (100kmx100km squares - just to pick a number, I'm unsure of what it really is).

As for the IAF altitude, I believe P3D will clear you to the specified IAF altitude as shown in the approach for your AFCAD file. You can edit this in ADE.

There's a ton of information that is quite valuable on the FSDeveloper forum. Look out for posts by a name Jim Vile. He was the master of this stuff; may he rest in peace.

Good luck!

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10 minutes ago, DChockey08 said:

As for the IAF altitude, I believe P3D will clear you to the specified IAF altitude as shown in the approach for your AFCAD file. You can edit this in ADE.

How would I find the AFCAD file for a specific airport (say, KRME or KSYR for example)? Thanks!

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Posted (edited)

This is actually a complicated question.  If you're shooting the full approach without radar monitoring, than the published restrictions would always apply.  But if a controller is vectoring you to final or is radar monitoring you prior to joining the procedure, he/she can and will descend you to the MVA (Minimum Vectoring Altitude) for that area.  The MVA is not published and can be lower than the MSA or other altitudes specified in the charts (MVA is determined by radar coverage quality and local elevations and obstructions).  However, once cleared for the approach, you must comply with all published altitude restrictions lower than your last assigned ATC altitude.

With all that said, from what I know about default FSX/Prepar3d ATC, it's probably doing it wrong :-).

Edited by MadDog
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4 minutes ago, MadDog said:

This is actually a complicated question.  If you're shooting the full approach without radar monitoring, than the published restrictions would always apply.  But if a controller is vectoring you to final or is radar monitoring you prior to joining the procedure, he/she can and will descend you to the MVA (Minimum Vectoring Altitude) for that area.  The MVA is not published and can be lower than the MSA or other altitudes specified in the charts (MVA is determined by radar coverage quality and local elevations and obstructions).  However, once cleared for the approach, you must comply with all published altitude restrictions lower than your last assigned ATC altitude.

With all that said, from what I know about default FSX/Prepar3d ATC, it's probably doing it wrong :-).

Fair point as well about the MVA! The specific approach I noticed this on is in a flat area, and the MSL altitude that ATC gives you is 200 feet above GS intercept, so it's a perfectly safe altitude. But it's below the altitude specified at the IAF, and I just wondered why. That may be the answer.

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6 minutes ago, mtr75 said:

The specific approach I noticed this on is in a flat area, and the MSL altitude that ATC gives you is 200 feet above GS intercept, so it's a perfectly safe altitude. But it's below the altitude specified at the IAF, and I just wondered why. That may be the answer.

Yup... I imagine Prepar3d ATC is using the FAF/Intercept altitude to determine how low to descend you.  This would be similar to real-world as long as there aren't any nearby mountains or hills or antennas for you to bump into.

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Radar Contact v4 has an option for NOTAMS for departure and arrival airports. Check the option if you're flying into an airport in mountainous terrain. You will be instructed to descend IF ABLE. That last bit is crucial as the vertical watchdog is turned off until you advice control you are able to carry out instructions.

Obviously more applicable to arrivals then departures but the option is there for both.

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