I have been flying with P2A for two weeks or so. The version I have is Pilot2ATC_Update_2700_x64_Beta7L. I've found that the program assigns altitudes to the different legs on the plan and that's fine. The cruise altitude is accepted but altitudes are added after the TOD. This is also fine but as the flight plan gets closer to the approach segment it gives me some doubtful altitudes.

On one of my flights ATC had me descend to 3000 ft when I was 119 nm from the IAF. Certainly that is too low for a B738. The altitudes in the flight plan were good but ATC decided to send me low.

The STARs sometimes have dual altitudes, a minimum ATC assigned altitude for turbine powered and a MEA that is could be used by aircraft not landing at the main airport in the STAR. If we look at the Bradford 8 STAR for KORD we see that the distance from IKK VOR to the BDF VOR is 150 nm. There is a FL180 for the entire route which is assigned by ATC but there's an MEA of 3000 and 2300, both also assigned by ATC if relevant.

Certainly you don't want to fly an airliner at 3000 feet for 150 nm, but that's what appears that P2A is doing. I was flying another STAR when ATC told me to descend  to 3000 but I used this one to illustrate.

How does P2A decide the altitude assignment? If I see an altitude that is too low or at the MEA during planning, is there a way to change it?

Thanks in advance.

When cleared to descend via a STAR, it does not mean to descend immediately to the assigned altitude, but rather delay descent if desired and then descend at your own rate, adhering to the STAR's altitude restrictions.  Sometimes the TOD is after the start of the STAR and you will be given clearance to descend via the STAR, slightly before you reach the first waypoint of the STAR.  In that case, just keep going at cruise altitude until you reach the TOD, then start the descent at the rate in your flight plan.

If the STAR is shorter, the TOD may occur before the STAR starts.  In that case, ATC will start you down before the STAR, usually giving an altitude to cross the first waypoint at.

If you're at FL400+, 119 NM is about the right distance out to start a descent, depending on your descent rate, groundspeed, etc.  P2A uses all these factors, along with any published procedures, to determine when to give clearance for the descent.

The altitudes in the flight plan are the pilot's planned altitudes.  ATC does not necessarily follow them, other than the altitude restrictions.  You can change the altitudes by double-clicking the Pln Alt cell, but that is really only useful for VFR flights where you are free to fly whatever altitudes you wish...Although, on an IFR flight, you can request different cruising altitudes before the descent.

Dave