A Compulsive Obsessive’s Guide to Checking If Your Flight Will be On-Time

In the travel industry, “on time” is a vague statement of aspirational nothingness rather than a committed promise.

Not that I’m a compulsive obsessive about anything.  Oh no!  But……

In the terrible world of air travel, and the surrendering any sense of control over one’s environment that one is required to do prior to entering the airplane terminal, being able to at least know if your flight is likely to depart on time and get to its destination on time is one small sense of order in an otherwise disordered world.

Sure, you can sign up for alerts from your airline (although recently a foreign airline I was booking flights with asked for a hefty fee in return for texting flight updates rather than volunteering to give them for free), and you can check the display boards and listen for the announcements when you’re actually in the airport.  To be fair, the airlines, in general, have greatly improved their information sharing about flights but if they’re going to start charging many dollars for this, that’s far from fair.

Even if free, there are still sometimes occasions when, for example, at 2pm a flight shows as departing on time at 2.30pm, but the inbound plane hasn’t even arrived yet, so everyone in the gate area – except apparently the airline staff – knows that the 2.30pm departure is not going to happen.  More aggravating is to be told at 2pm that your 3pm flight will leave on time, and while it hasn’t yet landed, you feel okay with that – until you find out that the inbound flight is running two hours late and hasn’t yet even departed the airport it is flying from to get to your airport so of course won’t/can’t possibly get to your airport in time to fly you out at 3pm.  Another case where, if you have the full information, you and everyone else except the airline staff can obviously and simply interpret the facts to understand your flight is going to be later than they say.

This is equally helpful if instead of doing the flying, you’re simply arranging to go and collect someone from the airport.  Knowing when to collect someone is just as important.

Why Do Airlines Lie About Late Flights?

There are (at least) two reasons why airlines lie about delayed flights, in addition to a toxic mix of sheer stunning incompetence and utter uncaring attitudes.  The first reason is because they don’t want to lose passengers – they don’t want their most valuable passengers – the ones who have paid the highest fares and who can therefore cancel without penalty at any time, shifting to another flight on another airline as soon as they are aware of problems on their originally booked flight.  If the airlines advised, several hours in advance, that a flight was going to be significantly delayed, there’s a measurable chance that such high-yield passengers would see if there was another way, on another airline, to get where they wanted to go.  But if the airlines delay that announcement as long as possible, and then spoon out the bad news in small 15 minute increments, the airline manages to keep all their passengers, even if there were better alternate flights available.

The second reason is because delays are more complicated than they seem.  Sure, the inbound plane that is designated to then fly you on your flight to somewhere is running late, but the airline might be still deciding whether it will juggle which planes it has and where they next go.  We’ve often seen a case where a particular plane (as identified by its registration number) was designated to fly a series of flights – say, for example, DEN-LAX-DFW-ORD, and a second plane was designated to fly, say, BOS-MIA-DFW-SAN.  But at some stage during the day, the two planes get swapped over in Dallas so the first plane, which is running late, no longer then continues on to Chicago but instead goes to San Diego, and the second plane, which is on time, goes to Chicago instead.  That can make sense, depending on how many passengers are going to each next destination, how many then need to make connections to additional flights, and various other operational issues.  (This is a very simple example.  Perhaps there are changes involving a third and fourth plane too.)

There’s also a measure of misplaced optimism in some of the airline expectations.  For example, it seems that sometimes, general air traffic delays take each airline by surprise, even though you can see that the airport is causing most flights to experience 30 minute delays.

The bottom line is that what the airline tells you is invariably the very best possible case scenario, and only sometimes a realistic statement of what will occur.

The Steps to Take to Understand Your Flight’s Likely Timings

We were going to suggest the first thing is to simply see what the official expectation of your flight’s departure and arrival times will be, but what’s the point, because the very next thing you’re going to do is check whether the official status is realistic or not..

So, no matter what the official expectation, you want to make your own decision about what to expect.  You should start by trying to determine whether your plane is likely to be at the gate in time for you (and all the other passengers) to board and be theoretically ready for an on-time departure.

After you’ve worked out if you’ll have a plane to transport you, you should then see if there are any likely delays at the airport you are departing from, any possible problems (most likely weather related) on the route you’ll be flying, and whether your arrival airport is open and operating normally.

1.  Official Flight Plan

The airlines start off by posting their planned flight times strictly as per their published schedule, and usually, that is first shown without gates assigned at either the departure or arrival airport.  But as time gets closer to when the flight will operate, they start to firm up details (although, as you surely know, gate changes can happen pretty much at any time prior to when the plane pushes back, even after it has started to load passengers).  However, as a comforting reality check, once you see a gate assigned, you know that at least someone, somewhere, has started to acknowledge the possibility of your flight actually occurring.  That is a great step forward, when you see the gate assignment.

Some airports delay announcing gates, even though they know well in advance what they’ll be, because they don’t want to have too many passengers in a too-small gate area at once.  So, even though there might not be gate assignments displayed at the airport, the chances are that in the internal airport and airline systems, gates have been assigned some long time previously.  Your objective is to find a way to see what those internal systems are showing, rather than wait for the delayed official display of it in the airport terminal.

We suggest you go to one or two websites to see what the airline is projecting and telling Air Traffic Control.  We like FlightAware.com, (rather than link all the websites everywhere in the article, we have links to them at the bottom) because it shows a lot of information.  In particular we love that it distinguishes between when a flight touches down at its destination and when it actually pulls up at the gate and turns its engines off.

That’s the most useful time point if you’re wanting to know when you should be at an airport to meet someone flying in.  And if you’re at the airport waiting for the incoming flight to arrive and turnaround to become your outgoing flight, it is helpful to know maybe ten or twenty minutes before the plane appears at the gate that at least it is now on the ground at your airport.

When you look at this information, be aware that sometimes you’ll see nonsensical/impossible data.  Take a look at this information, for example, about a flight that is currently mid-way to its arrival.  What do you see that is clearly nonsense?

Full marks if you noticed that this KLM flight between Amsterdam and Vancouver is planning to land at 4.01pm and then instantly be at the gate, at the same time, even though the schedule allowed 28 minutes for on the ground taxiing, and there’s an average delay of 10-20 minutes.  Anyone, except an airline scheduler, would be able to conclude that if the plane is touching down at 4.01pm, there’s no way it will be at the gate before perhaps 4.10pm at the earliest.

Note that later in the flight’s progress, this was updated.

2.  A Sense of Perspective

We like to visit Flightradar24 to see the recent operational history of the flight.  If your flight has been consistently late every day for the last couple of weeks, that sounds like a too-tight schedule and it seems like a fair bet to expect it to be late again for you (the opposite also applies, some flights, particularly the last of the day, often seem to run very ahead of schedule).  It is also interesting to see, from their site, where the delays occur – are they due to late departures, or late arrivals?

Note also that increasingly airlines add “padding” – extra time – to their schedules.  That means that just because a plane departs late, the extra time might allow it to seem to “make up time” and still arrive on time.  Of course, it isn’t truly “making up time” in the sense of flying more quickly at all.  While pilots will often say something like “We’re sorry for the late departure, but we’re going to see if we can make up some time on the flight and hopefully get you to the gate at the other end at close to the scheduled time” the reality is that almost never will they fly faster, because that costs more money in fuel, their making up time is simply due to using the built-in slack in their schedule.

So extra padding built-in to the schedule can mean that the time you’re expecting to arrive might still be achieved, even after a late departure.  You can look at the Flightradar24 data and get a sense of that by noticing what happens when the plane does leave late.  Does it often make up lost time during the flight, or does a late departure always lead to a late arrival, too?

A similar concept is to see – does an ontime departure (or, even, sometimes, an early departure) always lead to an ontime arrival, or is the schedule tight and the flight sometimes/often delayed so that it arrives late, even after an ontime departure?

3.  Track the Incoming Flight

This is a very helpful part of understanding the reality of when your flight will depart.  Until your plane is at the gate and boarding your flight’s passengers, many things could go wrong.  So, unless you see the plane at the gate, it is very helpful to understand where the plane is and when it will be at the gate.  Although “your” plane might be reassigned and switched at any time, the closer it gets to pulling up at your gate, the more likely that the plane designated as becoming “your” plane actually will be the one you board.

Unfortunately, you have to pay for a premium level of access on FlightAware to see the tail number of the plane assigned for your flight.  So go to the Flightstats website and lookup your flight, then click the “View Flight Details” button to see the airplane tail number.

Now go to Flightradar24 and select the “search” option.  Put in the aircraft tail number, and, hey presto.  You see where the plane has been for the last several days, where it currently is, and where it will be continuing on to.

For example, we are looking for details on Delta flight 2635 from Seattle to Los Angeles on Saturday afternoon, 13 April.  We found out its tail number is N3756, and so we see this information

This is actually, by chance, an interesting set of flight records.  Look down to 11 April.  There’s clearly some bad data there, because we see it operating as DL1657 and arriving into Fort Myers at 11.31pm on Thursday 11 April, but on the same day, at 3.08pm, it is apparently flying out of St Louis and going to Minneapolis.  There’s then a cancelled flight, and the next thing we know, it is leaving Fort Myers on probably Friday 12 April at 12.33am.

Anyway, looking to the parts that actually interest us, we confirm that it is assigned to operate the DL2635 flight, and departing at 3.30pm, which is the officially scheduled time.  We see that it is due to arrive into Seattle on an inbound flight from Phoenix, with a scheduled arrival of 2.38pm and a projected arrival of 2.16pm, and because, at the time we looked this up, the plane is already in the air and on its way to Seattle from Phoenix, we’ll accept there’s a high degree of probability that, if not early, it will at least arrive on time, and with a scheduled 52 minutes for turning the plane around, that all looks achievable and good.

So, based on what we see, we’re feeling fairly comfortable about this flight.

4.  Airport Delays

Let’s now see if Seatac Airport is operating more or less as it should, or if there are ATC and other issues creating delays for most arriving/departing flights.  Because this example is on a Saturday afternoon, pretty much the entire system across the US is working fairly smoothly.  We can check by going to FlightStats and clicking Airports and then we can choose airport delays to get a picture of delays across an entire region/country/continent, or by choosing Current Conditions and typing in the airport code for the airport we most want to know about.

Good news.  Seattle is experiencing very little delay and its projection is for decreasing delays.  Understanding the trend is important, particularly if you’re looking at what is happening at your arrival airport, which might be somewhere you won’t reach for six or more hours.

If we wished, we could also check LAX to see what sort of delays are happening there, too, and that too shows a low delay factor and decreasing.

You might have noticed some simple weather information shown on the delay pages.  This brings us to the next point.

5.  Weather

You may already know how airlines love to blame “weather” for delays, and now that we all have instant access at our fingertips to national weather maps and conditions, their claims about bad weather are often exposed as the thin lies they truly are.  The airlines have tried to make their claims harder to disprove by saying that “bad weather somewhere is impacting on ‘the system’ everywhere” but even that can now be researched.  If your incoming flight is on time, and your airport isn’t showing any delays, what/where/how is weather causing a problem?

To be even-handed, sometimes flights are delayed because there’s something you can’t easily research – another incoming flight with a lot of transferring passengers on it that is delayed.  Airlines sometimes, but not always, will delay a departing flight if they see there’s an inbound flight that would miss connecting with the departing flight, and quite a few passengers at risk of missing the flight (and perhaps any/all other flights for the rest of that day).

But, back to weather, you can choose to research the weather that the incoming flight is likely to experience, and also the weather your flight might experience too.

You might want to first go to FlightAware to get an idea for the route the flight is taking or will take, and then switch to a weather site to see what type of weather is on the route.  But note that, prior to an actual flight plan being filed, Flightaware will just show you the shortest standard route between the two airports, not the actual planned route which can sometimes (and, the longer the flight, the more often) vary considerably.

Flightaware’s information on the actual route flown and still to be flown by this flight – quite different from the theoretical shortest distance between LAX and SEA.  You can also see some weather information (green and yellow) on this map.


Weather.com provides weather maps for the entire world, for the US, the National Weather Service provides a nice map https://www.weather.gov/current and also forecasts https://www.weather.gov/forecastmapsWeather Underground gives you a selection of weather maps to browse through.  https://www.wunderground.com/maps

Note that most weather is not very impactful when you’re cruising at 35,000 ft.  Thunderstorms are the major exception to this, because the cumulonimbus thunder clouds can go way higher than that.

During winter, of course, snow can be a problem at airports.  This will usually be reflected in both the weather and the arrival/departure delay information.

6.  In-flight Progress

If you’re meeting someone, you’ll want to keep an eye on the flight’s progress and occasionally changing ETA.

We like to use FlightAware for that (see the image immediately above and the two closer to the top of the page), and only start tracking a flight once it has departed and is “in the air” on the way to where we’ll be meeting the arriving person.

Gate Information

Another use for flight monitoring apps is to get gate information.  This is particularly helpful when you’re on a somewhat tight connection.

As soon as you land and turn on your phone, check your own arriving flight to see what gate it will go to, and then check your next flight to see what gate it departs from, so that when you get off the plane, you simultaneously know where you are and where you have to go (you might have to also look up an airport map so you know where the gates are and whether you’ll want to turn left or right after exiting the jetway).  This website has terminal maps for about 200 of the larger airports around the world and can be a good place to start.  If you like to be well prepared, you can preload terminal maps before you start your journey of course.

Particularly with a tight connection, even little things like knowing if you turn left or right when getting out of the jetway can save a precious couple of minutes and help reduce the FUD (Fear Uncertainty Doubt) factors greatly.

Mobile Apps

The chances are that for much of this research, you’ll be at the airport or somewhere else, other than at work or home next to a laptop/desktop computer.

All three of our flight tracking recommendations have both iOS and Android apps (FlightAware, FlightRadar24 and FlightStats), and they’re all free, too.  Weather Underground and any number of weather apps are also available on both phone platforms.


The airlines and airports are often slow to update the information about flights, even though it is “out there” and available for them.  You can find out more by going to other sources of this information.

The free information on the internet and available through the websites and apps mentioned will give you a much clearer awareness as to what is likely to happen to your flight’s schedule.

4 thoughts on “A Compulsive Obsessive’s Guide to Checking If Your Flight Will be On-Time”

  1. Speaking as a long-ago UAL crew scheduler …Almost good article, but you ignore many subtleties and competing priorities.

    • All aircraft, their operational characteristics, and their ‘position’ in the corporate rotation are not equal. You can’t just swap planes. An aircraft at airport A scheduled to fly A-B-C-D may have routine maintenance scheduled at the C -RON point; its alternate a/c may be scheduled B-M-C-W, and ITS alternate aircraft maintenance schedule is at the C-RON before going on to W. Swapping each of them at their common points with other aircraft screws up multiple maintenance schedules for weeks…. in some cases taking one out of service for a day or two, generating more changes.

    • Not all flight and cabin crews are equal – indeed, most are on different route pairings than the aircraft and each other — if an airline has a mix of aircraft types and sizes, cockpit crews may not be current in every one, requiring a reserves call-up, and cabin crews swapping “up” may need additional persons called in from reserves – another delay. Further, there are Federal work-time rules and union contracts for both groups – duty / flight hours per day, week and month. It’s very common at the end of the month in several scenarios to be “out of time”, and not be legal to fly, and not have enough reserves available in certain cities. Sometimes it can be anticipated, sometimes not. Delay.

    • Further, obviously, all aircraft size and configurations aren’t equal – sorting out the missed connections here and downline can get ugly. And expensive. I have personally been swapped out of an extra-cost exit row to a standard economy seat. I’m 6’8”. I was not pleasant about it.

    • Airport slots are controlled differently – some are under contract (thus, the United Concourse, the American gates, etc.) and some controlled by airport CUTE / CUSS (Common Use Terminal Equipment and Common Use Self Service) – all of which are planned out months ahead. Good idea for gate-use efficiency, but maybe not when it hits the fan.

    • Some aircraft require certain ground handling equipment which may not be available at all gates. If all the gates are occupied -– typically weather related, but several other conditions as well – that additional duty time while waiting builds up for crews, but also cascades into delays all down the line when their limits run out

    • Further, by contract, UAL can’t “loan” an empty gate to Delta, nor do they want to help the competition because they have their own delays coming and going, , nor are the staff and equipment in position to do so, nor does the liability insurance allow it. More delay.

    • Weather alternates – when the aircraft diverts or is simply late – especially at shift change –, nothing and nobody is in place. Ten baggage handlers just went home, leaving three on duty for 5 delayed planes (one is an A380). 2 hours for baggage in; two more for baggage going out. CBP and TSA didn’t schedule overnight staff. Catering is closed. Some airports have noise curfews and ATC system holds – you don’t take off knowing your destination isn’t available.

    1. Hi, Art

      Thanks for your always insightful comments.

      Two quick points in response. First, these days many airlines have many fewer airplane types, making it easier to swap one plane for another at fairly short notice. I’ve observed that happen myself, most recently just a couple of weeks ago while tracking my daughter’s flight from Amsterdam to St Petersburg – the incoming plane to Amsterdam swapped at short notice (and for no obvious reason).

      Second, I think all your points can be summarized as saying “even when you think you know it all, you don’t – things can still go wrong and get worse, but are not likely to get miraculously better”. And – if that’s a fair distillation of these interesting operational insights – I’ll certainly agree with that!

  2. Number one travel rule observed over 50 years of business travel; If it is important that you be in some city on a specific day, WAKE UP IN THAT CITY. I cannot count the number of travelers I observed complaining about missed appointments, weddings, cruises, and the like. Commercial air travel is simply not reliable.

    1. That’s a sad commentary to offer, but indeed, absolutely utterly true. Whether it be the fault of the airline, the air traffic control, the weather, or random happenstance and not really a fault at all, the reality is totally as you put it so well.

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