Like many others, I have enjoyed piloting the Fenix in 2024, as it generally behaves very well in the new sim. However, in several recent flights, I have had difficulty getting the Fenix to enter a managed descent at the top of descent. My usual practice has been to set a lower altitude ( e.g., the final approach altitude) after reaching cruise altitude, and then to push in on the altitude knob when 5 to 10 miles from the TOD as indicated on the nav display. This has always worked well in FS2020 and in my initial flights in 2024. But no more. When I push on the altitude knob to commence the descent, the plane instead wants to enter vertical speed mode. I then have to use an open descent (pull on knob) to bring the Fenix down. I can manually bring the plane down in steps in this manner, and when I reach the altitude of the initial approach fix and commence the approach, I can push the altitude knob and the Fenix will enter managed descent mode and follow the descent path of the ILS to the runway. But I cannot get the plane to commence a managed descent from the top of descent. Anyone else observing this behavior? Any workaround? 
Thanks,

Rich

Open descent is a pull, not push. Not sure there is another type of descent other than with v/s

Edited January 20, 20251 yr by Max Kraus

Yes, open descent is a pull, and one must push the altitude knob at or prior to TOD to commence a managed descent to the lower altitude set with the altitude knob. My problem is that a push of the knob does not produce the desired behavior - starting the descent. Thanks. 

This has been discussed on the Fenix Discord. It has nothing to do with the simulator itself, it happened in MSFS 2020 for me and others plenty of times. Aamir (I believe) said that it's by design behavior when you try to start a managed descent over a certain distance from the destination airport, irrespective of your distance to your TOD. You'll notice that when that happens the MCDU scratchpad has a message on it along the lines of "NEW CRZ ALT 11000", for example. So I don't think that's something that's going to be fixed.

However, I've noticed that if you go into open descent by pulling, then wait 2-3 seconds, then go into managed descent, you get managed descent reliably. It's an annoying workaround, but it's worked reliably for me in all of my flights since I discovered it.

Thanks Leftos. I will try your suggested approach. For whatever reason, I did not have this issue with 2020 - must have been lucky regarding distance to destination airports!

Yeah, it's total luck of the draw. I've just gotten used to doing it the way I said every time nowadays, just in case.

47 minutes ago, Leftos said:

It has nothing to do with the simulator itself, it happened in MSFS 2020 for me and others plenty of times. Aamir (I believe) said that it's by design behavior when you try to start a managed descent over a certain distance from the destination airport, irrespective of your distance to your TOD.

Then how does one trigger this behaviour? I have never in 15 years of Simulated Airbus flying had that happen and this is the first time I hear of it.

1 hour ago, Leftos said:

This has been discussed on the Fenix Discord. It has nothing to do with the simulator itself, it happened in MSFS 2020 for me and others plenty of times. Aamir (I believe) said that it's by design behavior when you try to start a managed descent over a certain distance from the destination airport, irrespective of your distance to your TOD. You'll notice that when that happens the MCDU scratchpad has a message on it along the lines of "NEW CRZ ALT 11000", for example. So I don't think that's something that's going to be fixed.

However, I've noticed that if you go into open descent by pulling, then wait 2-3 seconds, then go into managed descent, you get managed descent reliably. It's an annoying workaround, but it's worked reliably for me in all of my flights since I discovered it.

I believe the problem in it changing the cruising altitude when trying to go into managed descent is if you are too far from the top of descent, like over 50 miles for instance. 

6 minutes ago, Bobsk8 said:

I believe the problem in it changing the cruising altitude when trying to go into managed descent is if you are too far from the top of descent, like over 50 miles for instance. 

Nope, it's happened to me even like 5nm from TOD when arriving at certain airports.

True. I have always followed the advice of Mike Ray’s (UAL Pilot) A320 training manual to push in the altitude knob and begin the descent at about 10 nautical miles from the TOD, as this would allow descent to begin more gently and eliminate the possibility of overshooting TOD. Has always worked like a charm until recently. Now I’m not sure if this advice holds anymore in the Fenix.

Happened again today in flight from KDCA to KBOS, with cruising altitude of 37000 ft, with arrival on ROBUC3 STAR and landing using ILS Rwy. 27. 

14 hours ago, rlashier said:

My usual practice has been to set a lower altitude ( e.g., the final approach altitude) after reaching cruise altitude, and then to push in on the altitude knob when 5 to 10 miles from the TOD

I'm not sure if this has anything to do with it, but could you be setting the altitude too early, regardless of whether you're delaying pushing managed descent until close to TOD? I  believe normal practice would be to leave the altitude set to the cruise altitude, and then when close to TOD adjust the altitude and go into managed descent.

13 hours ago, rlashier said:

Happened again today in flight from KDCA to KBOS, with cruising altitude of 37000 ft, with arrival on ROBUC3 STAR and landing using ILS Rwy. 27. 

I have had this happen as well on occasion and it is almost always going into KBOS.  You have to be at FL230 at FEXXX so TOD is quite a ways out so I assume it has something to do with the distance from airport.

1 hour ago, Flic1 said:

I have had this happen as well on occasion and it is almost always going into KBOS.  You have to be at FL230 at FEXXX so TOD is quite a ways out so I assume it has something to do with the distance from airport.

I placed a ticket with Fenix weeks ago about the Cruise Altitude changing, when trying to set managed descent mode. They replied back, asking me how far I was from the TD at the time. I said, I was at least 50 miles away, maybe more. They replied that this was a known issue and was being looked at. 

The aircraft will, at a specified distance from the destination runway threshold - no longer engage managed descent, but instead assume a step descent to a lower level - hence the new CRZ FL message. This is an actual function of the aircraft, whether or not it is being triggered erroneously, you will need to send a support ticket in for so someone can take a look.