Why does my ATC give descent instruction so late?

User Support Hub ATC, Traffic & NAVAIDs
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1

Hey,

I was flying on IFR from Bangkok to Singapore.

ATC told me to climb 39000 feet so I did it.
However, when I was a few NM away from Changi Airprot my ATC stayed silent and didn’t tell me to do anything yet.

However when I was on cf(finally approach) to the runway it only told me then to descend and maintain 2000 feet.

Obviously I wouldn’t have enough time to descend from 30000 feet to 2000 feet in just a matter of seconds.

This caused me to go around which is annoying when I had a clear runway.

2

The ATC must have changed since the last time I used it as it never used to take you to cruise level. Usually you would get asked to climb to somewhere in the 12 to 15 thousand feet range and that would be it. You would then have to request step climbs up to your cruise alt.

3

On any IFR flight I have done in the last few months, ATC always guided me to my cruising altitude and then back down at the appropriate time.

But we all know ATC is bugged in very mysterious ways that not even the devs understand.

4

Personal Comments and Observations

TOD prompt is better than it used to be, but I personally go by the TOD on my EFB vs the calculated ATC one, which could vary by as much as five minutes (traveling at that speed - that’s a lot of miles chewed up).

I don’t fly commercial, but on BizJet/GA IFR, I request descent manually once my EFB TOD is reached. ATC will fall out of synch and spam me a bit to climb back to cruise until I’m closer to the IAF. I don’t bother with STARs as ATC doesn’t understand it anyway. You can fly the STAR, but the spam will persist for a bit as you fly the route until the IAF, then the above applies.

FYI - Offline ATC works great, never drops, uses the same Localization language file that Azure/Online does.

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I will have to give it another go to see what changes have been made. Must be 2 years or so since Ive used it

6

If you don’t enter a cruise level into the “Flight Log” screen on the world map, you won’t get commanded to climb beyond your initial cleared flight level. It’s been this way for quite a while.

I always had this problem when importing a plan directly into the plane with Simbrief and not doing anything on the world map.

7

That’s probably the reason why then. I always imported from Simbrief as well. I’ve never used the World Map for anything other than selecting a Departure

1 Like
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This also happens to me when filing an IFR flight plan from within the simulator (via radio) after setting up the flight plan from scratch within the avionics. Mildly annoying when you’re in a light jet that can fly higher. :smiley:

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I had much the same problem with a late descent. That along with the constant requests to change frequencies got to me, so I changed the way I fly longer IFR flights. I let ATC handle my flight from clearance until I get to cruise altitude, then I cancel IFR, which allows me to fly without interruptions.

Once I get to TOD, I begin my own descent until I reach the airspace entry altitude, say 3500 feet. Then, when I’m about 20 miles away from the airport, I contact the tower and get landing instructions. I know that’s not the correct way to do it, but with ATC being as buggy as it is, that gives me the most consistent experience and it works for me.

Maybe Beyond ATC will fix all of that… I guess we’ll see.

1 Like
10

Hey who knows, with luck Asobo will improve the ATC logic in MSFS 2024 (though it’s not listed or mentioned in any materials they’ve put out yet, so who knows).

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The reason why ATC is late in giving descent instructions is because it is doing exactly what is in the flight plan. If the cruising altitude is 39,000 ft and your flight plan is imported from SimBrief, then your flight plan tells ATC to keep you at your cruising altitude until the IAF. ATC instructions are linked directly to the flight plan information.

Is ATC “broken” because it is doing exactly what you are telling it to do? Or are your instructions in the imported flight plan “broken”? MSFS has never said that SimBrief (or any other) flight plans are compatible and can be imported without errors. I don’t think flight plan compatibility is even a Wishlist item. SimBrief (and others) have said their downloads are compatible with MSFS.

The “fix”:

Create the flight plan using the MSFS World Map flight planner. When a flight plan is created in MSFS using SIDs, STARs, and approaches, the flight plan contains the necessary information about the correct waypoint altitude and speed restrictions needed by ATC. (Imported flight plans are missing this information needed by ATC.)

Workaround 1:

The workaround provided by SimBrief is to reselect the arrival and approach using the drop down boxes right after import. MSFS will then insert the correct waypoint information into the flight plan. I do this for every flight plan I import. I then save the flight plan with the MSFS information in case I want to fly it again.

Workaround 2:

Ignore ATC, use an alternative ATC, don’t use ATC at all.

Workaround 3:

Manually enter the flight plan including waypoint restrictions into the FMC. VNAV should provide correct descent instructions to the autopilot. (This workaround is used by PMDG and other developers whose aircraft CANNOT import MSFS created flight plans.)

MSFS is not perfect but is improving. ATC gives me correct vectors when indicated in a SID or STAR. ATC gives correct information to fly a missed approach and return me to the airport usually using the same approach.

Even with a correct flight plan, an aircraft still might be too high during an arrival because many waypoint restrictions are “at or above” a certain altitude. I calculate where my TOD should be to enter the first arrival waypoint altitude. I often ask ATC to descend to an altitude I am comfortable with BEFORE reaching a waypoint.

Finally, before every flight I review each SID, STAR, and approach plate in my flight plan (using SkyVector in the US). If I don’t specify a specific runway or approach in my flight plan, I review all the approaches for the destination before departure.

2 Likes
12

Wait, really? Like it actively gives you vectors, and you follow them, and they are correct? It’s never spontaneously given me a vector – I have to request the next vector – and they usually seem to be … not entirely correct.

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13

Most likely you didn’t follow IFR flight plan. I fly airliners with ATC and they always ask me to descend, usually a few miles before the calculated TOD.

14

I also had more issues when I did not go into the flight log to change my cruising altitude.
ATC works most of the time now. Occasionally I will pass my calculated TOD without hearing something and I will request altitude change via comms.

This is news to me. How does one do this?

15

It’s an option in Sound Settings I believe. I literally set it long ago and forgot it. :sunglasses:

1 Like
16

Until this ATC high altitude issue is fixed, during the en route stage, where ATC often has you climb far to high, as in Real Life, you can always “Request” Lower.

Somewhat frustration, but better than hearing ATC constantly asking you to EXPEDITE your climb to some unrealistically high altitude.

17

I’ve encountered that ATC frustration a lot in the past. I fly the Longitude, and with the latest Working Title mods, I now use a VNAV approach, and ignore ATC. VNAV has proved to be a lot more reliable in establishing a smooth descent.

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Honestly, I just about fell out of my chair when I heard the ATC vectors! In the past I’ve always removed the VECTORS waypoint during pre-flight. I forgot to do this on one flight and when VECTORS was displayed I was going to fix when ATC cleared me to the next waypoint. Yes, the vector instructions were correct.

The other times where “vectors” have been fixed is flying a missed approach. When reaching the missed approach hold fix, once I notify ATC they give me a new approach to fly (mostly the same one) and then give me vectors to the IAF to enter the approach. At this point it seems like ATC is “broken” because it will issue a climb to 10,000 ft (which is probably a default instruction) and then quickly issue a descent to 7,000 ft or whatever the approach IAF altitude is. In the past, flying a missed an approach was not handled well by ATC.

I WILL question ATC about their directions either by requesting an altitude change, directions to the next waypoint, or asking for a different runway or approach. If ATC approves a different runway and approach, the approach is issued as a “circle-to-land” with higher minimums to the original runway.

What surprises me most is that there seems to have been incremental fixes and improvements for ATC delivered in recent updates not published in Release Notes. Many of the things I’ve described have been through sel-discovery.

1 Like
19

I am only now learning VNAV in the CJ 4. How would this be done normally ? ATC decend orders and VNAV dont work well together unless you are going step by step. In reality, does one exclude the other ?

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I simply set the AP for VNAV, select the target altitude and let the AP take over when TOD is reached. ATC may start complaining but I just ignore them. The AP will hit the altitude of each of the waypoints in your flight plan on the descent. You only have to worry about selecting LOC1 at the proper time to capture the ILS.

Sometimes, the ATC descent order and the VNAV TOD are pretty closely aligned and there’s nothing to worry about.