[SENT BUG] A320 Initiates DES mode automatically

DESCRIPTION:
This submission is regarding the updated Managed Descent mode of the A320. If a STAR is loaded into the MCDU, and a lower altitude is dialed into the FCU altitude knob prior to top of descent, the aircraft will initiate DES mode and start a descent on its own without pilot interaction. This goes against Airbus autoflight logic. A descent must be initiated by the pilot by either pushing (managed mode) the altitude knob or pulling (manual mode) the altitude knob. There are a few factors which make this harder to implement in the current form:

  1. There is no top of descent “arrow” displayed on the ND
  2. There is no indication of top of descent on the DES page of the MCDU

In addition, the aircraft does not seem to adhere to altitude restrictions during the descent.

STEPS TO REPRODUCE:
For my trial, I created a route from KPHX to KLAX. My routing was KPHX 25R: KEENS2 MESSI ESTWD HLYWD1 KLAX RWY 25L Altitude flown was FL260. Approaching MNROE waypoint, setup the approach in the MCDU and enter 17,000 in the FCU. Do not push or pull the knob Observe the aircraft initiates a descent and enters into DES mode, a managed mode, without pilot intervention. HLYWD1 STAR chart included for reference.!

HLYWD1_RNAV_STAR_KLAX|690x448

3 Likes

exactly the same issue i have. there is no tod indication arrow (even with the a32nx mod) and the autopilot will initiate the descend by itself at the invisible tod however if you have navigraph airacs it will follow the altitude constraints.
the descend pattern is ridiculous though. it’ll start with a -4000 fpm descend and settle at -2200 later on. this means that it’ll descend to the altitude constrain level but way too early resulting in a steep descend leveling off way too early and then continue the steep descend after the constraint to the next one.
it’s always a way too fast descend then level off then fast descen again etc. totally unrealistic

Completely agree. There are simply too many inaccuracies with the default and mod A320. I appreciate the effort, but knowing that I have a stable, deeply-simulated A320 on two other platforms, there is no reason for me to fly either version in MSFS2020. I’ll stick to GA here as I’ve said before. For the casual flyer, the default airliners are good enough. For anyone wanting more than that, they are lacking, rightly so - They are default aircraft. Waiting patiently for the “heavy” hitters to present the latest to the platform.

I’ve just had this issue twice in a row. For now I’ve engaged selected air speed mode when it happens to maintain the original speed. It honestly feels like it might be more accurate given my position when it happens (nearing descent), but I’ve also not had any change in altitude from ATC or managed altitude mode. Then again the flight plan altitude constraints have always been significantly lower than what ATC wants and I’m never sure which is accurate.

The real issue here is the Airbus auto flight logic does not automatically initiate a descent at TOD like a Boeing. It isn’t designed to do that. The pilot has to either initiate the descent by pushing for a manged descent or pulling for selected mode which is essentially an Open Descent, similar to FLC in the Boeings.

If the pilot forgot to initiate this and the TOD was passed, the PFD would indicate “DECELERATE” reminding the pilots to begin the descent.