# How can an airliner make up for time lost?

If a plane has been delayed at the origin how does it make up for the lost time? Does the pilot need any special permission from ATC to increase the speed so that it can cover the lost time or has the pilot the power to make such kind of decisions?

• Hello LearningPhase, welcome to Aviation StackExchange! – DeltaLima May 3 '16 at 12:04
• I feel like there was another question about an airplane making up for leaving late, but I can't find it now. I did find this question which is related and could also be interesting for you. – JPhi1618 May 3 '16 at 13:43
• A lot of times the pilot can't increase speed, so the only resolve is to have less time at the gate at the destination airport before turning around. I can't tell you how many flights I've been on that arrived late, and missed my connection. Or arrival flights that came in late and had short turn around times. – Ron Beyer May 3 '16 at 14:38
• It's worth noting that flight schedules frequently have some extra time built in (e.g. a flight that's only in the air for 35 minutes commonly has 1:05-1:15 scheduled in my experience,) so even a flight that's delayed in departure by 20 minutes often arrives on time if it encounters no other delays. – reirab May 3 '16 at 14:41
• Possible duplicate of Who decides how fast commercial aircraft fly: the pilots or ATC? – fooot May 3 '16 at 14:54

## 6 Answers

According to ICAO Annex II (Rules of the air) 3.6.2.2(b):

Variation in true airspeed: if the average true airspeed at cruising level between reporting points varies or is expected to vary by plus or minus 5 per cent of the true airspeed, from that given in the flight plan, the appropriate air traffic services unit shall be so informed.

So the pilot in command has the right to increase speed, just as well as the air traffic controller has the right to limit it. However, as airliners normally cruise fairly close to their maximum speeds, this isn’t very effective. Recovering lost time by increasing speed is at best 1 to 3 minutes per hour.
Better ways are to request possible shortcuts from ATC and change altitude for better wind and temperature.

• @LearningPhase, it's customary on StackExchange sites to wait a decent amount of time before accepting an answer to give other people a chance to provide what could be a better answer. I personally wouldn't accept an answer for at least 24 hours, and then probably longer than that. This might be the best answer, but you may never know if you accept too soon. – JPhi1618 May 3 '16 at 14:06
• @KirkWoll, Oh, of course, but questions with an accepted answer are far less likely to get additional answers so a better answer may never come. – JPhi1618 May 3 '16 at 14:39
• As an example: I was flying to Phoenix from the east coast. A combination of leaving slightly late and a headwind, resulted in an estimated time of arrival that was almost an hour late. The pilot requested and received a change in flight path (lower altitude and a more southerly route, I believe) that resulted in arriving on time. Actual distance covered was actually greater, but the lack of the heavy headwind more than made up for that. – Michael Richardson May 3 '16 at 15:07
• @JPhi1618 down with the green checkmark tyrant! power to the upvotes! – Mindwin May 3 '16 at 16:42
• @Sami show us a reference that says it is mandatory for the pilot in command to accept it. Yes, a controller may make the request, but the pilot can refuse it in a location without statutory speed limits. – Ryan Mortensen May 4 '16 at 14:38

That's a common scenario, that you're pushing off the gate late and would like to make up time. There are a number of ways that making up time can happen, although how much of that the pilot can affect doesn't often amount to a huge impact.

The flight is scheduled for whatever length of time, gate-to-gate. This accounts for the sorts of delays that the planners foresee when they're building the schedule: it's winter, so the aircraft may need to be de-iced. It's a busy time of day, so they plan on a slower taxi than simply driving out to the runway & taking off. The flight is usually scheduled around a moderately worst-case headwind/(lack of) tailwind. And so for the 1+00 (in the air) flight, you might be scheduled for 1+30 gate-to-gate.

And if some of the negative factors don't materialize, then you'll under-fly the schedule, which is nice. Maybe the delay at the gate caused you to miss the "morning rush hour" and you did get to taxi right out, no line or delay, and take off. There's no precipitation, so no delay for de-icing. The tailwinds are better than average today, so instead of 1+00, your flight will only be 0+55 in the air. All good things!

But none of that is really under the pilot's control.

The two places that the pilot can most affect things are, going faster, and getting shortcuts. Going faster essentially means using more gas, and sometimes guys are willing to do that... the high-school tour group is in danger of missing their connecting flight & being stranded in the hub for the night, let's go fast & get them there! Another version of going fast is flying at a more "speed efficient" altitude, usually around FL290 or FL300. If winds are all the same, you'll generally get more speed there because your maximum indicated airspeed (Vmo) and limiting Mach number (Mmo) are very close around that altitude. The tradeoff is, however, that you are burning more gas by doing this compared to going higher.

If you have the gas to burn, this can typically work.

Also, you can request shortcuts. Depending on the filed route and what's going on in the airspace, this may get significant savings. From the West Coast to DFW or IAH, you're typically routed around the north or south side of White Sands. But, if it's Saturday night and the restricted area is cold (not in use), then you may be cleared direct right through it & save some significant time. Of course, requesting shortcuts also saves gas (unless it takes you off a wind-optimized route -- rare but possible), so there's no real reason not to do it on every leg.

ATC may or may not cooperate with your plans. If the restricted area is hot, then you don't get the shortcut through it. If you're inbound to a busy terminal area (DFW, LAX, IAH, BOS, etc) then ATC probably has a sequence in mind, and they won't approve anything that changes the orderly flow of aircraft into the arrival. In fact, they may assign you a speed in order to fit the sequence together.

Other than that sort of planning, though, they typically don't mind if you fly fast, and if they aren't too busy, ATC usually approves requests for shortcuts that don't have you driving through restricted areas (or other special use airspace).

How much time can you make up as a pilot? If you really want to burn the gas, you might make up 5-10 minutes by going fast on a typical 1-2 hour flight, but those extra minutes are getting pretty expensive when you do that. Shortcuts may give you another 5 minutes or so, in the best case. (Longer flights tend to be more direct, as a % of the time, so you can't get the bigger & bigger time savings on the longer flights with shortcuts as you do with speed, compared to the short flights.)

But when a pilot tells you that he's going to make up 20 minutes off the planned flying time, most of that will probably be already baked in (tailwinds, no delays, etc) rather than things that he's doing differently than he otherwise would. (It's still a nice line on the PA, though.)

And some days, none of the above works the way you hope, and the late flight doesn't get any earlier, or even gets later, despite your best efforts. Speed, time, and distance can just be a bear, sometimes!

"Block" times are most often padded to cover any delays like this. FlightStats has a good explanation of what goes into calculating block times. The short version is that carriers publish the "quoted" time it takes to go from block-to-block. Pushing back from the departure gate to pulling into the destination gate. As shown in the FlightStats link, some quote a shorter duration for the same segment.

On the destination side, nobody ever complains that their flight landed early. Problems for the airlines that do this is that when a plane is on the ground, you're paying money to the port instead of making money flying the plane.

Note that not all airlines have the same trip duration listed for a given flight segment. This can be tough to determine because such overlap generally requires one end be a large hub, and on the East coast US, these large airports are often slot controlled.

Padding block times helps accommodate WX (Weather), headwinds, tailwinds, etc. All at the expense of \$.

## Further Reading:

Interesting info on actual performance vs. Airlines published block times: http://projects.fivethirtyeight.com/flights/

Also background on how that infographic is built and what factors into the decisions: http://fivethirtyeight.com/features/how-we-found-the-fastest-flights/

• "On the destination side, nobody ever complains that their flight landed early." Hmmm .... I don't enjoy kicking my heels near the door of a deserted small airport late at night, just because the flight landed 15 minutes early, there was no queue for baggage, but the car that's coming to pick me up doesn't know about that (and I have no way to contact it). On the other hand if the flight is late, the car driver is getting paid by the hour to wait for me! – alephzero May 3 '16 at 23:50
• Sounds like a great argument in opposition to padding block times! – blaughw May 4 '16 at 0:00
• "Problems for the airlines that do this is that when a plane is on the ground, you're paying money to the port instead of making money flying the plane." Not necessarily. In my experience, at least, they just reduce the time the plane is scheduled for the layover by roughly the same amount, so the actual time spent on the ground (if everything's on time) ends up about the same. I've seen flight schedules where the plane's next flight was scheduled to depart something like 15 minutes after the scheduled arrival time, even on 737-size aircraft. – reirab May 4 '16 at 19:45
• I would argue that this is a gamble, and an exception rather than the rule. A carrier can take this approach, but if it backfires there is a high likelihood that stats for TWO flights will go bad instead of just one (late arrival dominoes into late departure). How a given airline plans ground operations can vary by city, etc. as well. If an airport is a Maintenance location for Carrier X, they would more likely plan more time on the ground to perform tasks. This is opposed to a city with maybe 2-3 flights per day for Carrier X, where in-depth inspections are less likely. – blaughw May 4 '16 at 20:07
• Man this got way off-topic! :) – blaughw May 4 '16 at 20:08

On NMOC (Network Manager Operations Centre) there is one member of each airline, and in case of fleet delays, due to weather for example, they discuss and instruct the ATC to expedite one or some flights, clearing them to fly direct, and sometimes, overtake leading traffics on the queue.

• Are you saying there is a group of airline representatives that instructs ATC which flights to expedite? What part of the world is this? – fooot May 3 '16 at 15:23
• These group of representatives are part of the ATC management flow control, and they, together, decide how to decrease the delays, expediting who really needs, in order to avoid further delays, impacting the ATS. Your comment seemed to me kind of prejudice, however, the team work really work. – eduardoguilherme May 3 '16 at 16:27
• I did not mean to be critical, I'm just curious about the process. Is this more of a day to day thing, general process improvement, or both? – fooot May 3 '16 at 16:44
• CFMU is the standard name of the Unit. It works 24 hour a day, and mainly coordenates with the RTCC and TWR Controls, minimizing the delays, caused by weather and some other disruptions. – eduardoguilherme May 3 '16 at 17:18
• @fooot, the network manager approves flight plans and assigns departure times for them in order to avoid congestion both at airports and in sectors. When there is a disruption (and there are always some), they coordinate with airline dispatchers which flights can accept some delay and which should get priority because they would cause further disruption somewhere else. It is the network manager that eventually assigns the slots, so they ensure (or at least should) all operators get equal treatment. – Jan Hudec May 3 '16 at 18:59

I am not a ATP, but I would be surprised if commercial flights went faster to make up time, even if they were delayed. The reason for this is that it is much more expensive because you burn fuel faster. To go at top speeds it is not a linear relationship and you could spend a lot of money to get a marginally faster time of arrival.

One free way to increase speed is to take advantage of winds at altitude. So, for example, if there are known to be favorable winds at 40,000 feet, you increase altitude to that level.

You do not need "permission" to go faster. The pilots are the bosses and ATC are the servants, not the other way around. If a pilot wants to go faster, he goes faster, and notifies ATC of the change and they adjust what they have to.

• Airlines typically will add more fuel and increase the cruising speed to try and reduce the amount of passengers who will miss their connecting flights. Mis-connect costs can add up very quickly and spending more on fuel can be cost effective in cases like that. – Mike Sowsun May 3 '16 at 21:20
• @MikeSowsun Ok, I guess it is a judgement call. The ATPs I talk to always seem to be complaining how the airline wants to cut their nuts off for using too much fuel. – Tyler Durden May 3 '16 at 22:02
• It is true that airlines always want to save on fuel costs. But in some cases, a little extra fuel cost could save the cost of overnight hotels and meals for 20 or more people. Cutting 30mins on a 10 hour flight just might make all the difference. – Mike Sowsun May 4 '16 at 0:15

On some planes (airplus, sorry no reference) there is a “sprint mode” that uses more fuel but goes faster. Airlines may therefore decide to time their flights not using the “sprint mode”, so as to save fuel costs, but be willing to use it if they are running late.

Flights are also timed so that can keep to timings even if the wind is in the “wrong” direction, therefore often a flight can go faster than the planners assumed.

• Are you saying Airbus planes have a "sprint mode"? I can't find anything about that. There is an adjustable cost index on modern aircraft which trades fuel vs. time. – fooot May 3 '16 at 15:15