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What could be the main reasons for a short-haul flight to be delayed over an hour in-flight?

Recent Lufthansa LH 2227 CDG-MUC flight took off only half an hour after scheduled time, but landed at destination delayed nearly an hour and a half.

enter image description here

Meaning (if I am reading these stats correctly) that this particular flight spend an hour extra in the air over scheduled time. I begin to question if there is enough fuel for the plane to stay that long extra?

I flew the very same flight few days ago and that flight also took of half an hours after schedule and landed fifteen minutes after schedule. Meaning that a plane manage to "work out" half of its delay en route. This particular, pictured flight not only didn't work out its initial delay, but also added another hour to it while being in air.

I was always told (and saw that in my small commercial flying experience) that

  • short- or middle-haul flights delayed 15-30 minutes on take-off,
  • long-haul flight delayed 60-90 minutes on take-off,

are nearly always able to land on-time, effectively "working out" their initial delay during flight, by flying faster etc. What happened or could happen here?

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    $\begingroup$ Don't forget departure is from the gate and arrival is again at the gate. Take off half an hour after departure is pretty much right on schedule for large airports. It also can't fly much faster to catch up with a delay—there is simply quite a lot of buffer in the schedule. $\endgroup$ – Jan Hudec Aug 27 at 19:38
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    $\begingroup$ "I begin to question if there is enough fuel for the plane to stay that long extra?" Well it would be pretty obvious if there wasn't enough fuel, no? $\endgroup$ – David Richerby Aug 28 at 10:19
  • $\begingroup$ @DavidRicherby That was a theoretical and more general question (not concerning this particular example) if plane departing for 1,5h long flight takes a spare fuel for extra 1+ hour of flight (thus around additional 75%). Directly saying this question should be understood as "I begin to question if this plane actually spent extra hour in-flight or whether there were some other circumstances that caused that huge delay". Which turned to be true. $\endgroup$ – trejder Aug 30 at 7:48
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If you look at the details, you’ll see the aircraft left the gate at 9:37, but only took off at 10:47.

They probably received notice of the issue in MUC pointed out by Machavity while taxiing to the runway (and then asked to park somewhere waiting for the airport to be ready for them). No sense returning to the gate for a delay like this which is expected to be relatively short.

A possible alternative (though probably not here) is they they had an issue right after gate departure which triggered a maintenance request. It happened to me once on some regional airliner which had an issue just when they spooled up the engines (or just after a few meters, don’t remember). Immediately powered down and had some part of the engine changed (or maybe just a filter or something similar) while we were waiting, took about an hour or so.

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  • $\begingroup$ It seems that your answer is much closer to the actual situation than Machiavit's answer above. Flightradar24 confirms that this particular flight took off at 10:46 and that the actual flight time was nearly exactly the same as average flight time (1:08). Thus this is better answer to my question, as I was asking why this plane spent over an hour extra in-flight. In fact it didn't. $\endgroup$ – trejder Aug 28 at 8:18
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    $\begingroup$ Another alternative, since the gate departure was quite late, is that they had to wait that long for a runway slot. That's happened to a flight I was a passenger on (or, at least, that's what the pilot told us was the reason for sitting an hour). $\endgroup$ – Peter Taylor Aug 28 at 9:34
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    $\begingroup$ @PeterTaylor In my experience, this just doesn't happen. A slot is just a capacity concept used to measure how many movements an airport can handle, and is used for capacity planning and "selling" those slots. Once an aircraft is ready to go, it just goes towards the runway and queues on the taxiway until it reaches the runway (mostly first-come first-serve, though there are some priorities as well). Waiting on the ground would be more an ATC hold related to the lack of capacity at the destination airport. But I'm just a passenger, maybe commercial pilots around can infirm/confirm. $\endgroup$ – jcaron Aug 28 at 9:41
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    $\begingroup$ I've also had a maintenance issue after leaving the gate: there was a problem with the towbar during pushback and they needed to get the maintenance techs to check the nose gear hadn't been damaged. I think that cost us about an hour. $\endgroup$ – David Richerby Aug 28 at 10:22
  • $\begingroup$ @jcaron Once the aircraft starts moving away from the gate, it's usually first-in-first-out, right? They can only hold so many planes on the passageways to the runway. $\endgroup$ – Mast Aug 28 at 13:05
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Munich was closed for a short time due to a security breach

The airport tweeted: “According to the information currently available, a person has probably entered the clean area of Terminal 2 through an emergency exit door from the unclean area.

“As a result, police measures are currently in progress.”

Terminal 2 is the home of Lufthansa, which operates hundreds of flights through Munich each day.

And this is likely the main kicker for this flight

While arriving flights are currently being allowed to land, the airfield is filling quickly and diversions may soon begin.

The plane probably circled as long as fuel margins would allow, rather than sit on the ground in a long line.

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    $\begingroup$ It might have sat on the ground—the aircraft is only considered arrived when it stops at the gate and shuts down. $\endgroup$ – Jan Hudec Aug 27 at 19:30
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    $\begingroup$ According to FlightView, LH2227 did not take off until 10:46 AM. $\endgroup$ – a25bedc5-3d09-41b8-82fb-ea6c353d75ae Aug 28 at 0:38
  • $\begingroup$ Thank you for your detailed answer. While airport closure could be a good reason here, the answer below given by jcaron (and comment above) are in my opinion more exact solution to this particular case, so I decided to accept the other answer. $\endgroup$ – trejder Aug 28 at 8:15
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re 'working out delays'

The flight uses an operational flight plan which shows the routes (waypoints), speed, altitudes. There are usually some compromises made, a shorter route may cost more (overflight fees) and a cheaper route may take longer. The company will usually select what is best ie more economical with flight time acceptable.

In exceptional cases like longer delays, the ops dept may choose a higher cost route to minimise the impact (more direct route or higher cruise speed). This is usually easier to do on longer flights of course, on shorter routes there may not be much choice.

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