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My understanding is that the runway should always be cleared, and occupied by no more than a single aircraft for takeoff and/or landing at any given time.

Is there any scenario in which ATC can clear two aircraft to occupy the same runway at the same time? Like clearing them to takeoff one by one: clear the front one to use part of the runway to takeoff first, and then clear the other at the threshold to takeoff.

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  • $\begingroup$ Does the FAA have an equivalent of the CAA 'land after' clearance? $\endgroup$
    – Dave Gremlin
    Aug 30, 2019 at 21:04

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There is another scenario other than "line up and wait" that the other two answers cover...

A "flight" of more than one aircraft may be cleared as a group to take-off. This can consist of many aircraft sharing the runway during take-off (and even landing).

So you can have multiple aircraft on the runway when:

  • A "line up and wait" order is issued to line up on the runway after another aircraft takes-off or lands. This is usually done so that the departing aircraft can get prepared while waiting for wake-turbulence to clear.
  • ATC clears multiple aircraft as a "flight". The aircraft must be part of a coordinated group and a single aircraft is the "lead" aircraft for the flight that receives/coordinates with ATC for clearances. The entire flight group will enter the runway and take off in a pre-coordinated fashion.

There are specialized scenarios as well, for example during Airventure Oshkosh. Aircraft will be required to "land on the dot" and multiple aircraft may be on the runway for take-off at the same time, although ATC coordinates them so that they don't depart at the same time, they are asked to line up "on a dot" (a colored circle on the runway) and will then be cleared to depart from there.

As an extreme example:

116 aircraft lined up on the runway and cleared for take-off at the same time.

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    $\begingroup$ How did this get signed off?! $\endgroup$
    – Cloud
    Aug 29, 2019 at 9:37
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    $\begingroup$ @Cloud Because they were extremely well-coordinated. ATC probably knew months in advance that they were coming and what time they wanted to depart, down to the minute. They had pre-flight meetings with the pilots and if you notice, the pilots had color-coordinated cards for every scenario. They also coordinated with Airventure tower in advance to be able to receive that many aircraft at a specific time. I'm sure they knew before they even took off that they would be cleared through the FISK arrival. $\endgroup$
    – Ron Beyer
    Aug 29, 2019 at 12:23
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    $\begingroup$ These are also very small planes that presumably don't need very much runway to take off. If this runway is designed for 747's, there's more than enough space to line them all up with room for take offs. $\endgroup$
    – Darrel Hoffman
    Aug 29, 2019 at 13:20
  • $\begingroup$ Nine aircraft synchronised take off: m.youtube.com/watch?v=mtNc8ZXuHVI $\endgroup$
    – Notts90
    Aug 29, 2019 at 13:41
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    $\begingroup$ 6:35 "Traffic, twelve o'clock, same altitude, zero miles." 😂 $\endgroup$
    – ceejayoz
    Aug 29, 2019 at 15:35
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Yes, it is possible, under some circumstances. However, your general understanding that only one aircraft is allowed on a runway at one time is correct most of the time.

There are a few obvious cases, also covered in the other answers. For instance, an aircraft can be allowed to cross or taxi on a runway behind another aircraft which is taking off or landing. An aircraft waiting to depart can also be cleared to enter/line up on a runway behind another aircraft taking off or landing. These examples are pretty simple, because only one aircraft is actually using the runway for takeoff or landing, the other is just taxiing behind. But actually, two aircraft can takeoff or land on the same runway at the same time in accordance with the below, and as stated in ICAO Doc 4444 section 7.10 on Reduced Runway Separation.

  1. An aircraft can land on a runway while another aircraft in front of it is also landing, provided that the first aircraft has touched down, is in motion and will vacate the runway without backtracking (doing a 180 on the runway).

  2. An aircraft can land on a runway while another aircraft in front of it is taking off from that runway, provided that the first aircraft is airborne.

  3. An aircraft can take off from a runway while another aircraft in front of it is also taking off, provided that the first aircraft is airborne (but still over the runway, and thus not clear of the runway yet).

ICAO suggests some pretty strict requirements in order to use these rules, such as the exact distance needed between the aircraft involved, as well as the type of aircraft, runway length etc. However, some states have pretty lenient rules. In Denmark, for example, it is largely up to the air traffic controller on duty to decide if conditions are safe to use reduced runway separation. The phraseology used is a little different as well:

  1. Instead of the usual "cleared to land", the phraseology used is "Land behind preceding landing (aircraft type)". The second aircraft will obviously have been informed of the first one, and weather conditions must permit the pilot to see the first aircraft at all times.

  2. Similar to 1, the phraseology is "Land behind preceding departing (aircraft type)".

  3. A normal "cleared for takeoff" is used, but the pilot of the second aircraft must have been informed of the preceding aircraft and have it visually in sight.

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Yes. It's a Minimum Runway Occupancy Time procedure, and is applied at specific airports after safety and layout assessments.

One such airport is London Heathrow. Below is from the UK AIP:

(...) should remain behind the subject aircraft but may cross the runway holding point (subject to there being no illuminated red stop bar) and enter the runway upon receipt of the clearance. There is no requirement for the subject aircraft to have commenced its take-off roll before entering the runway. Pilots must be aware that there may be a blast hazard as the aircraft on the runway applies power.

(Emphasis mine.)

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    $\begingroup$ Is this essentially "line up and wait behind" or does it actually enable an aircraft to takeoff/land while another aircraft is still on the runway? $\endgroup$
    – 60levelchange
    Aug 29, 2019 at 5:32
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    $\begingroup$ @J.Hougaard: Essentially yes, and the leading does not even have to be rolling yet. So it's queuing them on the runway just like the scenario OP asked about. More in the linked textual data. $\endgroup$
    – user14897
    Aug 29, 2019 at 10:18
  • $\begingroup$ OK. That's completely normal then, not just something done in the UK :) $\endgroup$
    – 60levelchange
    Aug 29, 2019 at 13:22
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    $\begingroup$ @J.Hougaard: Never said it was just the UK :) I gave an example with an official citation. Also not all airports utilize/allow this reduced ROT, or the UK AIP would not have needed to mention the point above about the preceding airplane. But yes, for busy airports this queuing is normal. The safety assessments are mentioned in 2.6 in Doc 4444, since the aim of this queuing is reducing separation once airborne, otherwise there's no need to queue or mention the not rolling part. $\endgroup$
    – user14897
    Aug 29, 2019 at 14:11
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Historically, scrambling military aircraft would involve several planes taking off simultaneously in formation, so this guaranteed more than one aircraft on the runway at once. In addition, the next formation to take off was generally lined up and ready to go behind them. For interception duties, this enabled as many planes as possible to take off in as short a time as possible, giving the pilots an invaluable few extra minutes to gain height in preparation. This can be clearly seen in this Pathe footage, where Spitfires and Hurricanes launch in formations of three aircraft.

Strategic bombers adopted (and still use) a similar technique called minimum takeoff interval, designed to get nuclear bombers airborne as rapidly as possible for a retaliatory counterstrike in the event of attack by nuclear missiles. With the high turbulence from preceding aircraft, takeoff does become very much more risky, but it remains standard practise.

Having more than one aircraft on the runway at once is therefore entirely familiar for military ATC.

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This is standard operating procedure for towplane-glider takeoff.

Clearance with ATC is covered by 14 CFR § 91.309

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  • $\begingroup$ The link makes no mention of the word "runway". And of course glider-tow would be one flight. Do you mean multiple tows at once? Please clarify. $\endgroup$
    – user14897
    Aug 31, 2019 at 14:28
  • $\begingroup$ Multiple aircraft (i.e. the towplane + the glider) on the runway at the same time is standard ops when launching gliders this way. The question asks about “multiple aircraft”, not “multiple flights.” Seems adequately clear to me. $\endgroup$
    – Ralph J ♦
    Aug 31, 2019 at 14:39
  • $\begingroup$ @RalphJ: That would be clear but irrelevant IMO, thus LQ. How else would a tow–glider takeoff? Unless Roger means multiple flights. $\endgroup$
    – user14897
    Aug 31, 2019 at 14:43
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    $\begingroup$ This is an unexpected but valid answer to a fuzzy question. $\endgroup$
    – bogl
    Aug 31, 2019 at 15:49
  • $\begingroup$ @ymb1 Launching gliders with an aero-tow is an example of what the OP asked about: if/when you can have 2 aircraft on the runway at once. It's a clear, responsive answer to the original question. $\endgroup$
    – Ralph J ♦
    Aug 31, 2019 at 16:43
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I've seen this often in Atlanta. An aircraft will start its takeoff roll, with the next aircraft behind the line. Once rolling aircraft is about halfway down the runway, the next aircraft will slowly start to move onto the runway.

If you're on board on the side you'll be taking off on, you can typically watch the preceding aircraft as it reaches V1 and rotates, just before your aircraft finishes its turn to line up with the runway.

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  • $\begingroup$ Likewise with a landing aircraft, the following departure may "position and hold" while the landing aircraft completes its landing rollout, so the following craft can depart as soon as the previous one clears the runway. $\endgroup$
    – GalacticCowboy
    Aug 29, 2019 at 12:57
  • $\begingroup$ @GalacticCowboy "Position and Hold" is outdated, the recommend phrasology is "Line up and wait": faa.gov/airports/runway_safety/news/current_events/lauw $\endgroup$
    – Tyzoid
    Aug 30, 2019 at 0:34
  • $\begingroup$ @Tyzoid The concept is still the same. $\endgroup$
    – GalacticCowboy
    Aug 30, 2019 at 13:15
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    $\begingroup$ @GalacticCowboy your point is valid. However, we do try to keep things as current as possible to avoid confusion for people who may come read this in the future. No sense educating someone on the old phraseology that will cause confusion if they were to actually use it. *Yes, a pilot should be trained on current standards, however, some things will stick in your head and are hard to get out.... $\endgroup$
    – FreeMan
    Aug 30, 2019 at 19:08
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    $\begingroup$ It's a great point that in these cases, you can actually see the previous craft taking off! ATL (the world's busiest airport, I believe) is the prime example. $\endgroup$
    – Fattie
    Aug 31, 2019 at 12:32
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If a runway has multiple crossing taxiways then ground control can clear several aircraft to cross the runway at the same time.

If a runway is not being used for landings or takeoffs (in favor of another runway) then it can be used like any other taxiway (other than the clearance and read-back requirements). On busy airports during peak hours this could mean the runway can be use as a holding point for aircraft waiting for their gate to become available.

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