A look at how airline pilots make up time in flight

How Pilots Make Up Time: 5 Tricks To Get You There On Schedule

Most people have experienced the feeling of being on a delayed flight. You board the plane and take your seat, only to look at the departure time and see that it has been pushed back.

You then spend the next few hours trying to work out how late you will be arriving at your destination. Will you make the last train, what time do you tell friends or family to come and pick you up?

However, on many occasions, the pilots will make up time and the flight will arrive significantly closer to schedule than on first look.

So, what’s going on? How do pilots make up time? Here’s a behind-the-scenes look, written by an airline captain, at 5 tricks pilots and airlines use to arrive closer to schedule.

Flying faster

Can pilots just fly faster? It sounds a simple solution to making up time in the air, but often it is the simple methods that work. And the truth is, yes they can!

There are 2 ways pilots normally can fly faster.

The first method is to increase their speed below 10,000ft (ca. 3 km):

  • In most controlled airspace globally, speed limits are enforced between 0-10,000ft
  • This is to help controller workload — it’s often the busiest portion of airspace — and to help streamline arriving and departing aircraft
  • Low-level speed limits also have some benefit in reducing aircraft noise near to the ground

Air traffic control will occasionally allow pilots to increase speed beyond this 250 kts limit, with most commercial aircraft capable of flying nearly 100 kts faster if allowed. It may only cover a small period of the overall flight time, however getting rid of this speed limit — “maintaining high-speed below 10” in pilot speak — can shave several minutes off the flight time.

The second method is simply to increase the cruising speed of the aircraft:

  • All airlines will have a standard speed setting they ask their pilots to fly at.
  • This speed setting is known as a cost-index, and is simply the trade-off between burning more fuel and flying faster, and saving fuel to fly slower.
  • Cost and environmentally conscious, most airlines typically require their pilots to fly near the most fuel-efficient speeds
  • Many airlines also prohibit pilots from taking additional fuel to simply fly faster.
  • However, for exceptionally late flights or operational reasons — such as arriving at a destination before bad weather or before the airport closes — pilots can trade fuel for speed.

Aside from the addition fuel burnt, the downside to this second method is that flying faster only really works on longer sectors. Pilots flying faster can save 30+ minutes easily on longhaul flights. On many shorthaul or regional routes, flying faster may burn more fuel, but will only save a couple of minutes at best.

Skipping the takeoff queue

Skipping the takeoff queue showing ATC tower and American Airlines a320

At most busy airports, it’s not uncommon for large queues of aircraft waiting to depart to form. Major internationals such as, China’s Shanghai, New York’s JFK, and London’s Heathrow Airport all consistently have taxi times approaching half an hour in peak periods.

Where delays are common due to the high volume of traffic, rather than simply miles of taxiing, late-running aircraft can occasionally skip the queue and depart from an intersection

How do they skip the queue?

  • Before takeoff, pilots will run computer calculations to determine the engine thrust, flaps and slats, and speeds required to perform an optimum takeoff for the runway length available.
  • At major international airports, runways are usually exceptionally long, so many departing aircraft can take off using only a fraction of the available runway length.
  • Pilots looking to make up time will often set the aircraft up to depart from an intersection point on the takeoff runway, hoping to skip some queuing aircraft lining up at the full length of the runway.

The benefits of skipping the takeoff queue can be huge — shaving 25 minutes or more off waiting times — but at the busiest airports the request is rarely carried out

More direct routings

Another way pilots make up time in the air is by flying a more direct routing. This means that instead of flying the usual, published route, the pilot will fly a more direct line to the destination. In other words, they will cut some corners!

Don’t aircraft fly the most direct route all the time? Generally, this is true, airlines would rather not waste additional time or fuel flying indirect routings, so time savings can be minimal.

However, there are occasionally some (huge) benefits pilots can take advantage of.

  • Flights are typically planned several hours in advance, and will be planned around any obstructions like airspace closures.
  • These airspace closures could include things like military exercises, weather balloon flying, or even laser / fireworks displays!
  • Often block-booked in advance, by the time the aircraft is approaching the airspace pilots occasionally check and find out that the operation has finished, and the airspace is now open, allowing large shortcuts.
Launch of a high altitude weather balloon, often resulting in diverted aircraft
High altitude weather balloon launch

Equally, in busy airspace such as mainland Europe, many airspace restrictions are to do with capacity constraints. Put simply, there are too many aircraft scheduled to fly through one “piece” of airspace at once, causing delays as aircraft have to fly around these busy areas or wait for their turn in the queue.

By flying at a lower or higher level — or even by being so late that the peak traffic periods have passed! — pilots can ask for more direct routings and shave several minutes off their flight time.

Taking advantage of wind direction

This one is a bit more complicated, but it’s all about using the wind to your advantage. It may not sound like much, but it can save valuable time, particularly if there is a strong tailwind for the duration of the flight.

There are 2 key ways pilots make up time by taking advantage of the weather, one involves exceptionally strong winds, and the other involves the opposite!

High-speed wind: Jet streams

A jet stream is a strip of fast flowing air high up in the sky which flows from west to east. It can blow at speeds of over 200mph (ca. 322 km/h), and this obviously has a giant effect on how fast an aircraft can fly in relative terms.

  • Commercial aircraft typically cruise at a Mach number that equates to around 550 mph (ca. 885 km/h).
  • If a pilot is flying in the same direction as the jet stream, their speed over the ground will be 750 mph, versus 350 mph for aircraft in the opposite direction.
  • This mismatch in flight times is why the average flight across the Atlantic between London to New York is 8 hours. But the average flight time for the return journey is over an hour shorter!

One thing to consider is that it’s normally not this straightforward. Jet streams vary in height, direction, and speed, so aircraft may not be able to take advantage of their location on many routes. Equally, jet streams can be very turbulent, so pilot’s and flight planners may wish to avoid them entirely on some days.

Light and variable wind: Runway switching

What if there isn’t a strong wind? This second method relates to the low-level winds, and is how pilots make up time without a helpful tailwind.

  • When the winds on the ground are light and variable, at quieter airfields, pilots can often land on the most favourable runway.
  • Pilots typically takeoff and land into a headwind.
  • By flying into a headwind, they reduce the speed the aircraft needs to reach over the round, using less runway on departure and reducing brake wear on landing
  • Many commercial aircraft have lots of performance available, and on hugely long runways, they can take off and land without a headwind if required
  • On days with light winds, pilots will often calculate the performance for a tailwind rather than a headwind, and if safe choose to land on the most time efficient runway
  • Pilots will elect to land on the runway that reduces their approach time or their taxi in time, or both, and can shave 5-10 minutes per departure and landing.
Landing a 737

Fudging the schedule

This final method airlines use to make up time is largely out of the pilots control. However, it’s a popular method for many airlines, and is also why industry statistics involving the “most on time” airlines are almost always not worth relying on!

Airlines and pilots work towards 2 target times for a flight, the block time, and the flight time.
The block time is the scheduled time from when the plane leaves the gate to when it arrives at the destination gate. This is the time advertised on online schedules, and what the arrival time printed on passenger tickets is based upon.

Block times include taxi out times, the flight time, an additional delay factor, and the taxi in time. In contrast, the flight time is how long it actually takes to fly the aircraft from A to B.

Virtually all airlines use statistical models to work out average flight times with seasonal weather conditions, and base their block times around this.

  • Some airlines choose to make their schedules as accurate as possible — giving their customers a realistic time that they will arrive at a typical day.
  • Others prefer to build large amounts of flex into their block times. This means that if they encounter any delays they will still be “on time” and on a typical day the pilots will always be able to announce they have arrived early.

Summary

As you can see, there are a few tricks that pilots and airlines can use to make up time. Often, it’s the simple methods that work best. So, yes — many times, pilots just fly faster!

However, there are many additional methods pilots will try to make up time, to get customers to their destination on time.

In the air these can vary from re-routing the aircraft around busy airspace, or bad weather, asking air traffic control to remove low-level speed restrictions, or taking advantage of strong upper level winds.

Waterspouts are weather hazards that can close airspace

On the ground, pilots might ask to skip takeoff queues, or even land on different runways to facilitate a faster get away. Finally, some airlines prefer to under promise and over deliver. They often allow additional time in the schedules, so that flights always tend to arrive on time or early regardless of minor delays!

So, next time you’re sat on a delayed flight, try not to worry too much. The chances are that the pilot will be doing everything they can to get you there as close to on schedule as possible.

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Josh
Josh

Flyingbynumber’s Resident Airline Captain — Josh

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