Originally Posted by Often1

This is not a doable connection. First and foremost, if your A departure is international, US requires you to be at the gate no later than T-30 (T-15 if this is domestic). While you will generally be permitted to board after that up until approx. T-10, if the flight is overbooked and at risk of oversale, US will offload you before it pays IDB/VDB compensation to others.

The time frames above are slightly too favorable. Not only does the arrival time at F denote the time at which the brakes are locked at the gate, but the inter-terminal shuttle runs on the ramp and aircraft have priority. This means that you may sit in the shuttle for an extra 5-10 minutes enroute if there is heavy departure/arrival traffic.

For planning purposes and presuming that your carry-ons are physically with you and that you are near the front of the aircraft, I would allow:

1. 10 minutes from brakes locked to shuttle at F.
2. 15 minute wait for shuttle
3. 20 minutes inter-terminal (including 10 minutes of ground stop time)
4. 10 minutes from shuttle to A gate (could be less if close gate)

That is 55 minutes. If this is an international flight, you need 1:25. If domestic, it is 1:10.

All of this presumes an ontime arrival at F. At PHL, depending on time of day, that is far from certain. PHL is in the middle of the worst ATC area in the country, prone to minor WX delays and it is short hops (if you are arriving at F it's not widebody) which bear the brunt of those.