Why Do Airlines Make Small Changes to Flight Times (Ask Cranky)

This is a great question, because I’ve wondered it myself for quite awhile. This gave me the chance to reach out there and see if I could get any more detail. Sure enough, I could. Let’s start with the question.

. . . I booked my tickets last week and got an interesting email from the online travel service this week that my return flights had been changed by the airline. The departure and arrival times were changed by 1-3 minutes, for the most part making the flights a bit longer. For example, my departure from Buffalo was changed from 4:30 to 4:27 (or it might have been the other way around).

Why would Delta make such small changes to the flights? I’m a private pilot and come from a family of pilots, so I’m familiar with airspeed versus ground speed, but there’s no way they can predict the weather nearly two months out; and I know about flying at maximum economical speed as opposed to maximum possible speed, so I’m wondering if the rising fuel prices have caused them to adjust their speeds a bit to save fuel. But that is just a wild guess.
Perry

This happens on all airlines, but I’ve certainly noticed it happening more frequently on Delta than others. You think your flights are all set and then you get a schedule change notice saying that the arrival time has moved by a minute or two. Why the heck are they doing this?

I went to Delta for the official response and was told this:

. . . when the schedule is first published, it’s not operationally sequenced, so small adjustments are made on certain routes – basically massaging the departure and arrival times slightly for the best operational efficiency and connectivity. As your reader noted, these are minor, a minute here and there.

In other words, when Delta first puts the schedule out there, it’s not perfectly timed to fit into the entire system. Little tweaks of a minute or two can make a difference. That sounds really nebulous, so let me try to fill in the blanks.

A schedule is put out there nearly a year in advance. Often, that won’t be the final expected schedule. Ask CrankyMajor tweaks happen along the way, but the big ones are usually done when you’re a few months out. There might be some new routes added since the schedule was first put out there. Some routes could be cut, frequencies could change, etc. So at a large airline like Delta, when the schedule firms up, they might find that tweaks of a minute or two on other routes can help.

There are a few other reasons I can think of that would make this worth doing. Look at it through the eyes of the reservation system. This is more of a small change than a big one, but let’s say that Delta flies from Buffalo to Tampa via Atlanta and it takes 4h32m. Then let’s say that US Airways can get you there in 4h30m. If there are a lot of people that fly that route, it might make sense for Delta to find a way to shave 3 minutes off the connection time. That could make it the fastest way to get from Buffalo to Tampa and it could actually have an impact on bookings. Of course, you only do this for larger markets.

There is also the issue of weather. Airlines use historical weather patterns to determine how long flights will take. For example, winds are much stronger in the winter than the summer, so a flight from JFK to LAX is scheduled to take longer in the winter. It’s possible that as weather data comes in, the airlines make slight changes to adjust to the new expectations.

The last reason I can think of for this is simply one of airport issues. Let’s say that Buffalo has construction going on this winter. Delta might want to lengthen the expected flight times to account for the potential ground delays, even if it’s just a few minutes.

I’m sure we have some readers who know more about this than I, so feel free to chime in below.

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26 Comments on "Why Do Airlines Make Small Changes to Flight Times (Ask Cranky)"

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Joe B
Guest

I was wondering if it had anything to do with bettering on time arrival on a chronic poor performing route. Any truth to that?

Greg
Guest

I hypothesise that it might do with sequencing at the airport. If a group of flights are all scheduled for 4:30, would moving your flight to 4:28 put you at the front of the line for takeoff slots?

Michael
Guest
Speaking of schedule differences, what’s with the big jumps in international fights with Delta? For instance, I’m flying DL 108 ATL-MAD on 3/25, dep 6:45 and arriving at 8:15. According to Seat Guru, 108 has many different times (as I also noticed in my search for different dates): 108 ATL 4:40p MAD 7:25a Boeing 767-400 108 ATL 6:35p MAD 8:15a Boeing 767 108 ATL 6:35p MAD 9:15a Boeing 767 108 ATL 6:45p MAD 8:15a Boeing 767 108 ATL 6:45p MAD 9:15a Boeing 767 108 ATL 6:55p MAD 9:15a Boeing 767 108 ATL 6:55p MAD 9:40a Boeing 767-400 108 ATL 7:05p… Read more »
Michael
Guest

Also, I have to comment re: Delta and their attempt at making the fleet up to date with Wi Fi etc (previous post from weeks ago)…Can you tell I’m the only one in the office today and already over it?

Overhead movies on a 9 hr flight to Madrid from your fortress homebase in Atlanta? That’s not exactly up to date! When I flew to AMS on UA in ’05, they even had seatback movies/monitors. That just doesn’t seem right!

tking18
Guest

Delta is in the process of putting seatback AVOD on all 747, 757, and 767 aircraft that currently do not feature it. They expect to finish in 2013.

Michael
Guest

I know, I read that, but it still just doesn’t seem right haha!

Dan
Guest
I know a thing or two about this stuff, but I’m far from an expert. There’s a lot of stuff involved with publishing a flight schedule, from airport operations to crew scheduling. Let’s touch on crew scheduling for a moment, as it’s not something that was discussed in Cranky’s answer. Most major airline pilots (and regional ones too, with a notable exception being Southwest) get paid hourly — but only based on flight time. These pilots typically get paid on a “block or better” basis, which means they get paid for the block time (gate to gate) as published in… Read more »
Comanchepilot
Guest
A few comments: 1. Airlines pay pilot pay based on actual block time. Scheduled time is not important except for bidding minimum monthly guarantee. So adjusting is not all that important 2. The ATL-MAD time changes are due first to the daylight savings time change. It changes first in the US, then in Spain, then they add a flight for summer from JFK and since they only have one gate in MAD they need to stagger the flights to permit boarding. 3. 2 or 3 min changes do not matter at all. ATC delays, weather, weight, air temp will add… Read more »
Evan
Guest

If I may tweak your #1 comment a bit…Block or better, as mentioned above, is a more correct answer. If my actual block time is 20 minutes less than scheduled, I still get paid the scheduled time. If it is 20 minutes more, I get paid scheduled time +20 minutes.

Marvin S.
Guest

I would also speculate that the tweaks may also have to do with ground operations. Shifting around several flights by minutes may make baggage handlers, etc. more efficient at getting ALL the planes in and out of a terminal.

Dan
Guest

This part is true, too. I used to work on the ramp for a regional carrier, and the way our flights were set up was that each ground crew was responsible for six flights. It’s fine when there’s so much as a 5-minute stagger between flights, but during one schedule, there were three flights set to go all at exactly the same time. That sorta sucked.

David SF eastbay
Member
If this happens at a slot controled airport it could be a couple of minute time change to move a flight from one slot time to another to keep a slot or because another flight was added/changed. Kind of reminds be when I was 18 (which was eons ago) and working a retail job and we would have to change the price on something and it only changed by a penny. That was back before bar codes so would have to acutally change the price tag on the item. It always seemed like they spend more money to raise the… Read more »
Brad
Guest

This is the same for all airlines across the board, scheduling is constantly tweaking flights. The gate times, the assigned A/C, the crews, and even the guage of the A/C can be changed multiple times through the life of the flight (i.e. loaded in schedule to safely arrived at destination). These changes occur often in the months before, and sometimes weeks before departure

FlyLBB
Guest
The VP of Continental was correct in that most carrier publish a block that has an ‘acceptable’ block time and an ‘acceptable’ plane for a given route. So, CO may schedule IAH-LAX with block time Xh XXm and on a 738. Closer in, the schedule will get fleeted and tweaked based on an fleet or profitability optimization program. So, a 738 turns to a 753 and a more realistic block time schedule. Then, more tweaks based on airport operational issues such as connection failures, gate slotting, crew scheduling, time of day, the list can go on. It’s true you can… Read more »
Chad
Guest

It could also have to do with minimum connection times … One minute could make the difference between a valid connection and an invalid connection.

Esteban
Guest

I believe this is all about “on time” departure stats and the legalities of bumping off connections (i.e. no duty for airline to hold/help you out if you miss).

courtneyaj98
Member

I’ve also seen minor tweaks to block times requested by crew scheduling to make particular pairings legal either at the request of crew scheduling committees (to create a highly productive trip for a crew base that is otherwise not getting a lot of good pairings) or to eliminate an overnight when bumping up against hotel room availability constraints in particular cities where it can be difficult to procure hotel rooms at crew rates (BOS, for example).

Eric
Guest
Don’t forget to mention the logistics of scheduling crew and aircraft routing. A schedule made a year in advance doesn’t begin to predict how planes and crew will be routed to actually fly them. A few months before departure time the airline will take the thousands of legs that make up a day and find ways to match aircraft and crews to them. Sometimes two flights can’t easily be given to the same aircraft, but only just. Perhaps they would yield only 27 minutes on the ground when the airline prefers 30. The airline will then change one or the… Read more »
Tom
Guest

I’ve recently seen two 10 minute changes to the same flight from Melbourne to Singapore on Singapore Airlines. About 6 months ago they changed the flight to 10 minutes earlier, shortly before the actual flight they changed it back to the original time. Sounds still weird to me as on a flight over 8 hours, 10 minutes hardly make a difference.

Esteban
Guest

yeah all of the above. wouldn’t have anything to do with money. like bilking passengers.

David Z
Guest

Don’t know if you wrote about this before, CF, but how about an article why airlines make BIG changes this time? Hehe.

Esteban
Guest
me = continental silver elite = upgrades before merger me = gold elite = #19 on list post-merger I’ve never been that low on an upgrade list. even as a silver. I stand by this: it’s always about money: saving it or forcing more out of passenger. I sat next to two platinum elites on my flight from boston to houston today. we were in the exit row. lucky us. whether it’s departure time changes or bilking elites, i’m done with all of this “frequent flier” jazz. the only response from a consumer is “lowest price fare.” so say we… Read more »
ferrelled
Member

And this cynic chimes in: Another columnist opined that, by changing the schedule times by a minute or so every now and again, flight tracker software like Yapta can no longer match the tracked flights with “real” schedules. How many times have I, as a Yapta user, been met with a message saying my fight can no longer be tracked only to find the departure time is the same but the arrival time is a minute or two different. Not that any airline would be that devious.

Perry
Guest

Thanks for taking my question and looking for the answer! And thanks to everyone who suggested answers.

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[…] got a follow-up for an old Ask Cranky post today. In January, I wrote about why Delta might change flight times by a few minutes here and there. I received a similar question from someone about a United flight recently, but with United, I can […]

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