What constitutes an on-time flight? The question has always been asked — do some airlines pad their schedules to account for airport delays? 

The answer is yes. Consider the case of American flight 1487, which operates daily from New York’s JFK to Phoenix Sky Harbor Airport. 

The flight is listed as departing at 10 AM and arriving at 12:54 PM local time. 

But the actual flight time is often less than expected. In a recent week, the aircraft pushed back at least 21 minutes late every day but still arrived either on time or up to 39 minutes early. 

So, if you’re making a tight connection in Phoenix, check real-time on-time stats online by searching the airline and flight number.