Clairvoyant pilots
September 30, 2019 7:51 AM   Subscribe

While flying out of LaGuardia yesterday I was listening to the tower on LiveATC. I noticed that many of the planes on the runway I could see (31) began their takeoff rolls a couple seconds before they received takeoff clearance. This wasn't a typical 'rolling takeoff' in which the plane goes directly from the taxiway into their takeoff roll. The planes were told to line up and wait and came to a full stop at the end of the runway, and began rolling a couple seconds before the tower cleared them to take off. I have never seen this before and cursory googling doesn't turn anything up. Is this permissible, or is it pilots bending the rules at a busy airport?
posted by googly to Travel & Transportation (4 answers total) 2 users marked this as a favorite
 
Best answer: There's some time delay on LiveATC. Their FAQ says "typically less than 20 seconds".
posted by allegedly at 7:54 AM on September 30, 2019 [19 favorites]


Response by poster: Of course! I can't believe I didn't think of that. Weird that I have never noticed it before.
posted by googly at 8:24 AM on September 30, 2019 [1 favorite]


Best answer: To answer your other question ("Is this permissible?"), the answer is no. No one's going to get busted for moving a couple feet, but starting a takeoff roll without clearance is a definite violation. As to the "clairvoyance" part of it, separation minimums are standardized, and if you're flying in and out of one particular airport a lot you definitely start getting a feel for the flow of things. You can start identifying which controllers are on duty, and they all have their individual styles (within the operating regulations, of course).
posted by backseatpilot at 9:13 AM on September 30, 2019 [9 favorites]


There's a delay on every Internet audio stream. It's inherent to the medium. You can hear it easily if you have a local broadcast FM radio station that also provides a stream.

Most of the time we don't notice it because most of the time the thing we're expecting the audio stream to sync up with is an accompanying video stream, and that's similarly delayed.

Some network audio protocols, such as those used for phone calls, are specifically designed to minimize this kind of delay because the round-trip-to-Mars effect is irritating when trying to have a two-way conversation. But for various technical reasons those protocols are harder to use over the Web, so general-purpose streaming services like LiveATC don't bother.
posted by flabdablet at 9:57 AM on September 30, 2019 [3 favorites]


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