Making Up Time in the Air: How Airlines Keep Flights on Schedule

Have you ever had a flight depart behind schedule and yet somehow arrived in at the scheduled time? While airlines may have a reputation for being obsessed with efficiency, there are a few ways that your plane can make up some time in the air. However, it’s not like the airlines are holding out on us – there are good reasons why our planes can’t just fly faster.

It’s hard to be a commercial airline. The competition for passengers on many routes is intense, and when you consider the volatile nature of fuel costs it’s no wonder air carriers are always struggling to keep costs down and increase efficiency.

One of the more noticeable casualties of this penny-pinching happens before the plane even leaves the ground. If you’ve ever been bumped from a flight due to overbooking, you’ve been a victim of this practice. The airlines intentionally overbook almost every flight, with the end goal being to fill the plane to the brim. The airlines have put a lot of time and effort into figuring out the odds of a given ticket being used, and it all lumps into an elaborate gamble that the airline makes in the hope that enough people will show up to fill up the plane. In actuality, this is just one of many bets that companies make every day to remain competitive in the field of commercial aviation.

Big 777, Small 145
From Flickr user hugh llewelyn

Unfortunately, even when the airlines get it all right, there are still countless unpredictable factors that can disrupt the whole process. Inclement weather, staffing issues, and maintenance are all factors that can cause delays to passengers and scheduling problems for the airline. Over the summer, I was on a flight through Newark and we had a delay because one of the codeshare airlines hadn’t moved their big Boeing 777 so our tiny Embraer 145 regional jet could get to the gate.

However, even though we didn’t even start boarding until after our departure time, we still managed to touch down at BWI a few minutes ahead of schedule. The person next to me was pleasantly surprised to hear this since she had a tight connection to make, and speculated out loud how we could have come into such luck. Fortunately, she happened to be sitting next to a guy who loves nothing more than blabbing about all modes of transportation.

In my experience, there are two main ways that airlines can make up time, and the first depends on how airplanes actually get from place to place. Unlike general aviation, commercial aviation is tightly controlled. Big jets can’t simply get up in the air and point at their destination airport; they need air traffic controllers to route them around storms, across restricted space above other airports, and to make sure they don’t run into other jets or pass through the violent wake turbulence left behind by other aircraft. To do this, the Federal Aviation Administration (FAA) has laid out a network of radio transmitters all across the country. Controllers can use these transmitters as waypoints, essentially giving the pilot a series of directions and having them play connect-the-dots as they zig zag across the country.

Just a normal flight from San Francisco to O’Hare…

Needless to say, some paths are more efficient than others, and because of wake vortices and other safety factors there are only but so many airplanes that the FAA can cram down the most direct routes.  When a flight is behind schedule, the FAA will usually do what it can to help and assign it as efficient of a route as possible. Pilots are accustomed to being assigned one of the less efficient paths, especially in the event of inclement weather, but sometimes they get lucky and get to take a virtually direct route.

However, the real way that airlines make up time in the event of mechanical delays or weather detours is really simple: fly faster. When I got to this method in my explanation, my seatmate was understandably upset. “Well, why don’t they just fly faster all the time?!”, she said, minus a few colorful adjectives. The straight answer is that they easily could, but then we’d be polluting the atmosphere a lot more while at the same time paying a lot more for our plane tickets.

It’s simply not in the best interest of the airlines to fly faster all the time: people are used to a cross-country flight taking about 5.25 hours, and moreover they’re not willing to pay the extra fuel costs that it would take to get us there in the 4.5 hours that it would take if your 747 ran at its top speed of mach 0.855.

Flight Speed (horizontal axis) versus
Fuel Consumption (vertical axis)

Just like driving your car, once you get above normal cruising speeds every little bit faster that you go causes a major increase in fuel consumption. On the highway, you start to lose efficiency above 55-65 mph, hence the nationwide 55mph speed limit that existed in this country from 1973-1987. Above that speed, pollution and fuel consumption start to increase at a faster rate than the engine’s performance, and that’s the real reason why it doesn’t make sense to drive your car at 85mph. Well, that and safety reasons:

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About Peter Kauffmann

I'm a transportation engineer living and working in the District of Columbia. By day, I analyze traffic patterns and create multimodal transportation plans for new and exciting developments in the Greater Washington region, and when I'm not on the job I enjoy backpacking, biking, and classic movies.
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