Many years ago, I read an article in Air & Space in which a bush pilot demonstrated the short-field capabilities of his airplane by taxiing out and then taking off across the width of the runway. What are the regulations regarding this sort of maneuver -- when ATC clears you to take off from a runway, are you required to take off down the runway, or is this merely customary?
1 Answer
If you're cleared for takeoff from runway 28, for example, you are expected to takeoff along the centerline of that runway. If you want to takeoff across the runway you should get an approval/clearance from ATC.
An ATC "clearance" for takeoff from runway 28 means that your magnetic course during takeoff must be the same as the magnetic alignment of the runway (approximately 280 degrees in my example - exact runway numbering is rounded to the nearest 10 degrees). You would not be in compliance with this clearance if you took off across (perpendicular) to this runway.
This is a pertinent Federal Aviation Regulation:
14 CFR91.123(a) states the following:
When an ATC clearance has been obtained, no pilot in command may deviate from that clearance unless an amended clearance is obtained, an emergency exists, or the deviation is in response to a traffic alert and collision avoidance system resolution advisory. However, except in Class A airspace, a pilot may cancel an IFR flight plan if the operation is being conducted in VFR weather conditions. When a pilot is uncertain of an ATC clearance, that pilot shall immediately request clarification from ATC.
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$\begingroup$ Can you imagine the traffic separation concerns if somebody went to take off perpendicularly from a runway at an airport with three runway in a triangular configuration? Or maybe even worse, parallel runways: taking off from 25R in LAX perpendicularly, you're either pointed right at 25L, or at the north complex of runways (24 L/R). Yeah, I could see Tower getting pretty spooled up about somebody doing that! $\endgroup$– Ralph J ♦Commented Jun 2, 2023 at 3:46
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$\begingroup$ @RalphJ ....Yup! $\endgroup$– user22445Commented Jun 2, 2023 at 4:35
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2$\begingroup$ The ATC instruction "N12345, fly runway heading, cleared for takeoff 28" would be pretty clear. Is there a source for the "along centerline" requirement? For instance, if the "... fly runway heading..." part of the instruction was omitted, the pilot could turn when he pleased after takeoff; could he legally take off at say a 20 degree angle to the centerline in the absence of both conflicting ATC instruction and prior coordination? I'm not disagreeing with your answer, but curious about a more specific rule than "must follow your clearance." $\endgroup$– Ralph J ♦Commented Jun 2, 2023 at 15:20
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7$\begingroup$ Gallup conducted a poll of 100 tower controllers and asked them if they expected a pilot to make their take off roll following the magnetic heading of the runway, or take off perpendicular to it. 99 responded that they expect mag heading of the runway. The 100th rolled their eyes so hard they fell out of their seat, banged their head on the floor, and was too stunned to answer... $\endgroup$ Commented Jun 2, 2023 at 15:49
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$\begingroup$ @RalphJ. Generally speaking the (vfr) pilot, in my experience as a pilot and former controller, will advise the controller (Ground or Local) on what they would like to do after takeoff (e.g. request a straight out departure, westbound departure, crosswind departure, stay in the pattern, etc.). If not, the twr will solicit this info and issue a clearance/instruction accordingly - "Fly runway heading, westbound departure approved, etc." If I was responsible for providing separation these matters would be resolved before I issued a takeoff clearance. $\endgroup$– user22445Commented Jun 2, 2023 at 21:37