If I, pilot, have to make a stop at the undesignated parking position for some reason, such as FOD or ground handlers crossing in the ramp area, it is mandated that I have to contact ATC to explain why I have to stop?

Is there any global reference that describing when flight crews have to make a contact with ATC?

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    $\begingroup$ FOD is something that ATC would want to know about, so they can clear it. Ground handlers crossing your cleared path is an incursion, and would also want to know about it. I'm not sure what you are asking? Any time you deviate from an ATC instruction you need to talk to them. $\endgroup$
    – Ron Beyer
    May 25, 2018 at 13:52
  • $\begingroup$ Not really talking to ATC at that point, you'd be talking to Gnd Control. $\endgroup$
    – CrossRoads
    Jan 17, 2019 at 20:05
  • $\begingroup$ I'm not sure what you're asking. Does "undesignated parking position" mean somewhere in the movement area or in the non-movement area? For your second question about when to contact ATC in general, this question might be helpful. But the requirements to contact ATC will be different in different countries and for different types of flight (e.g. VFR vs IFR). If you can give us more details about your scenario, that would be helpful. $\endgroup$
    – Pondlife
    Jan 20, 2019 at 3:33

2 Answers 2


Is there any global reference describing when flight crews have to make contact with ATC?

On the ground, you need a clearance from ATC when you are on the maneuvering area, which consists of taxiways and runways. The ramp/apron is typically not part of the maneuvering area, and as such not controlled by ATC, although many large airports have some sort of ground control for these area.

In the air, you need a clearance from ATC whenever you are in controlled airspace. Some countries additionally require pilots flying IFR to be in contact with ATC even in uncontrolled airspace.

Note: ‘controlled airspace’ means an airspace of defined dimensions within which air traffic control service is provided in accordance with the airspace classification; (from SERA, EU 923/2012)

  • $\begingroup$ The thing is that you need clearance to move. If you stop, and for unexpected reason on top of that… $\endgroup$
    – Jan Hudec
    Jan 17, 2019 at 18:58
  • $\begingroup$ "In the air, you need a clearance from ATC whenever you are in controlled airspace." - Class E airspace is controlled airspace, but you don't need a clearance to fly VFR there. Maybe you can clarify this point? $\endgroup$ Jan 18, 2019 at 16:32
  • $\begingroup$ @TannerSwett Class E is controlled airspace for IFR flights, but not for VFR $\endgroup$ Jan 18, 2019 at 20:42
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    $\begingroup$ @TannerSwett I've added the definition for controlled airspace (according to the EU) to my answer. Here is an extract (also from SERA) regarding class E: "Class E. IFR and VFR flights are permitted. IFR flights are provided with air traffic control service and are separated from other IFR flights. All flights receive traffic information, as far as is practical" $\endgroup$ Jan 19, 2019 at 16:57
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    $\begingroup$ Class E is controlled, meaning that ATC service is available. VFR is not required to get a clearance in class E, though, or even talk to ATC at all. This leads many VFR pilots to mistakenly call it uncontrolled. $\endgroup$
    – StephenS
    Dec 22, 2019 at 18:45

Whenever you are operating under a clearance—whether on the ground or in the air—you have to inform ATC of any deviations. However, other concerns—controlling the aircraft—take priority. So you actually inform ATC as soon as you can safely do it, after the fact.

When you are cleared to take-off, you are implicitly cleared to abort, when you are cleared to land, you are implicitly cleared to go around and in any other circumstance you have enough free space around you that you won't run into anybody else (properly controlled) if you take some time.

So when you are taxiing along and your engine sucks something up and quits, you first slam on the brakes—because you definitely don't want to hit anything—then you do the memory items from the engine fire or failure checklist and only then you key the mic and announce something like “Tower, N123AB stopped on taxiway K due to engine failure. We might have ingested some foreign object.” (and if the fire alarm came on, ask for the firefighters). The next aircraft behind you either sees you well enough to stop in time, or (if it's really bad fog) has a lot of distance.

The worst case is probably emergency descent, where when you retard to idle and deploy the spoilers, you'll be through the next assigned level 1,000 ft below in about 10 seconds, but that only happens up where everybody is required to have a transponder, so you can probably trust the T-CAS for a bit.

For a real anecdote, I'd quote How It Flies:

I didn’t like what I was imagining, so I pulled the throttle to idle and stomped on the brakes. I also keyed the transmitter and said “Tower, Two-Four-Kilo is gonna hold our position for a moment”.

Read? Stomped on the brakes without having any confirmation that he should—because he had an—absolutely correct—hunch that the other guy would bust his clearance and land on the runway he was cleared to take off from and not the parallel one he's been assigned. You first control the aircraft as safely as you can, and then tell ATC what is going on.


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