What does the P stand for in this flight? flightaware.com/live/flight/AWE751P
I think what is going on here is that they are adding the P (could be any letter) to the flight number (and call sign) to avoid the confusion of having two flights in the air with the same flight number and call sign.
AWE715 flies from Brussels to Philly, then continues on to Charlotte.
If the aircraft is late arriving from Brussels, US may decide to start up a new aircraft in Philly and let it depart to CLT on time. So without the P, you could have Cactus 715 arriving in PHL and a different Cactus 715 waiting to depart, obviously not good so they add the letter P to the end of the flight number and the new call sign would be Cactus 715 Papa and problem solved.
You can look back in the history of AWE715 and AWE715P. I just looked at a few but seemed the only time AWE715P was used was when AWE715 was running late and arrived after AWE715P departed.
The P indicates a positioning flight.
Please explain further. Positioning for what? Loaded or empty?
The positioning flights we have tracked here from US use 9XXX numbers.
The post by 717Zulu is the correct answer.