Airlines make a huge deal out of on-time performance for their arrivals and departures. Of the two, which is more important, and why?

It’s always easier to finish on time if you start on time. On-time departures obviously facilitate on-time arrivals. That said, when push (or push back from the gate) comes to shove, the on-time arrival is more important. If a flight leaves the gate a few minutes late, it can usually make up the lost time en route either by cutting a corner or going a little faster (at the expense of a higher fuel burn, which is another expense to be watched).

Getting to the destination late has a huge negative domino effect. It affects passengers making connections. It affects the ability of the crew (or the next crew to get the airplane) to maintain their schedule. It affects the ability of the airplane to stay on track. It affects gate availability. The crew staying on schedule can determine if they can legally finish their day; if not, more flights may get canceled, driving up total costs. If the airplane is late, it may not be able to either make connections that it is scheduled for, or it may foul up a planned maintenance schedule. If an airplane is late at the wrong time of day, the gate schedule can be completely thrown off track, especially for an international flight, since customers need to be routed to clear Customs and Immigration.

The Department of Transportation allows airlines to call a flight on time as long as it arrives at the gate within 14 minutes of its scheduled arrival time. In the last several years, the airlines have gotten away from accepting this much slop. That 14 minutes can mean the difference between a passenger making or missing a connection, especially off of an international flight with bags to claim. Plus, it just doesn’t look good to accept a 14-minute delay as being on time. Adding to the stress on the schedule is the practice of getting away from having a bunch (if any) spare airplanes in the fleet.

On the other hand, an on time departure doesn’t mean anything if the arrival is late. The time can be lost because of weather on the field, en route, or at the destination; long taxi lines; mechanical issues, et cetera. Most carriers will accept an early departure over an early arrival, and they will emphasize an on-time arrival if possible. Early arrivals clog up taxi and ramp space, and they cost money in fuel burn on the ground.

It’s a balance and a never-ending battle. Schedules are constantly tweaked based on historical performance, taking into account changes in seasonal winds, ground traffic, and expected cruising altitudes. In the end, being on time on both ends is the goal, but it’s more important to roll to stop on time than it is to push right on time.—Chip Wright