I''ve found that US seems to be blocking too much time for their flights. Here are two examples:
CLT-FLL: Leaves gate 30 min late, a few minutes of taxiing, yet only arrives at FLL gate 10 min. late.
MIA-CLT: Arrives 30 min early.
Are they "cheating" to improve on-time performance? I''ve never seen anything like this on another airline.
Every airline does this. Some could call it cheating. Others would say it's better to pad block time than to jeopardize the operational reliability of airline. However, it can be expensive for airlines because most crews are paid block to block, based on scheduled block time vs. actual block time, whichever is greater. So if you're adding in block time to make your schedule more reliable, you may also be increasing your crew costs in doing so. But all airlines manipulate block times. You can hide a lot of operational problems that way.
PHL and LGA have some great "early arrivals" into outer stations WHEN there are no ATC/WX problems there. However, it is more common for these flights to arrive closer to skd than arriving very early.
If and when they ever debank PHL, the flight times from there can be adjusted accordingly. I've been keeping track of the 845 am dept from there, and its feast or famine. The other day it left the gate about 10 mins late (missing its normal spot in line) and arrived about 5 mins late after close to an hour taxi time. Another day it left a couple of mins early and made it in about 25 mins early after only a 20 min taxi time. There is such a wide variation, especially in PHL, of actual times, that I'm glad they currently have the flights padded as much as they do.