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:
- There is no top of descent “arrow” displayed on the ND
- 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.!