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At some airports, some taxiways have taxiway hold short markings (single dashed yellow lines against a black background). Do taxiing aircraft by default need to hold short of these markings if they're not instructed by ATC to do so?

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    $\begingroup$ Well, the first thing that enters my mind when I see this question is: What can happen if you don't, while ATC expects you to? What can happen if you do, while ATC expects you not to? How does the severity of these two compare? $\endgroup$ – a CVn Apr 26 '18 at 9:54
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    $\begingroup$ @MichaelKjörling a) Maybe Bang Bang, b) Maybe Shouty Shouty ATC c) Bang Bang worse than Shouty Shouty $\endgroup$ – Jamiec Apr 26 '18 at 10:30
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    $\begingroup$ @Jamiec You just won the Internet. $\endgroup$ – a CVn Apr 26 '18 at 10:43
  • $\begingroup$ @Jamiec, that's one of the best summaries ever. $\endgroup$ – GdD Apr 26 '18 at 12:54
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    $\begingroup$ Is there a specific country you are asking about? $\endgroup$ – fooot Apr 26 '18 at 16:58
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This is one biggest pet-peeves of mine that even old, experienced pilots have missed after years of flying.

Taxi instructions are just that: Instructions, not clearances. Mind you there are some clearances when on the ground aswell, crossing a runway, entering a runway, backtracking, maybe some others.. mostly involving the runway. But a general text like ‘Taxi to holding point Charlie via Golf’ is an instruction.

Ok, so the difference is just pedantic but there is one big caveat: when you are cleared to land, cross, enter on a runway you are guaranteed the runway is, well, Clear and will continue to be so for the ammount of time you need it to land/take-off.

This is not true for taxi instructions. You are instructed on what path to take on the ground, but the taxiways and route to your runway is most definitelly not cleared of other aircraft (unless we are talking about low visibiliy ops, but just bear with me for now). When taxing you are still supposed to look out for other trafic and try to avoid hitting other airplanes taxing around as much as you can.

You might be instructed to go via one taxi path and then later told to give way to another aircraft comming from your left. See how the path has not been ‘cleared’? It is not a clearance.

All this talk to sum up: entering/crossing a runway is a clearance. Crossing a (non-mandatory) taxiway holding point is not. Is the answer slowly building up ?

Crossing a runway hold short makrking (two dased lines and two solid lines) you need clearance.

Crossing a taxiway holding marking (or intermediate holding position, or cat 2/3 holding when not in low-vis) does not require one.

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  • $\begingroup$ Thanks. That definitely makes sense. While we're on the subject, does the same thing remain true for ILS critical areas? I'm pretty sure you don't have to remain clear of them unless instructed to do so. Is it a violation (e.g. could your PPL be suspended) if asked to remain clear, but you entered into one? $\endgroup$ – slantalpha Apr 27 '18 at 20:10
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A taxi clearance from ATC to a specific point on the airport gives the pilot authorization to cross all hold short markings or hold position markings for intersecting taxiways up to the clearance limit of his taxi instructions without stopping. If a pilot is given a hold short clearance at a certain position, he must stop and ask ATC for permission to proceed. If there is no conflicting traffic as the pilot reaches the hold position, ATC will normally give prior authorization to cross that hold point before the aircraft reaches it. Any position markings that require the aircraft to hold will be given in the original taxi clearance and would have been repeated back when receiving the taxi clearance. If not previously cleared beyond a hold point, the pilot must STOP until further clearance is authorized. Runway Holding Position Markings identify the locations on a taxiway where an aircraft MUST STOP when a clearance has not been issued to proceed onto the runway and no part of the aircraft can extend beyond the holding position marking. This is usually the last position of a taxi clearance limit and normally would be a change of frequencies for take-off authorization. One point to remember: if at any time you are in doubt of of your instructions, STOP! Don’t be embarrassed to ask questions of the controller. It’s okay to ask for directions or for progressive taxi instructions, if you are not familiar with the airport or route of taxi that has been assigned.

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    $\begingroup$ This is no longer true. Each runway crossing must be called out separately: aopa.org/news-and-media/all-news/2010/may/13/… $\endgroup$ – abelenky Apr 26 '18 at 14:22
  • $\begingroup$ Good point! I had interpenetrated this question to be taxi instructions for departure where more advanced precise planning can be made. Taxi instructions on arrival are more difficult to predict; hence, the need for more clarification from ATC to prevent mistakes $\endgroup$ – Loren Apr 26 '18 at 15:28
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    $\begingroup$ Its not an issue of "clarification to prevent mistakes". Your statement that "A taxi clearance from ATC to a specific point on the airport gives the pilot authorization to cross all hold short markings" is just wrong and a rules violation. ATC can only clear you to past one hold-short at a time. $\endgroup$ – abelenky Apr 26 '18 at 15:44
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    $\begingroup$ Obviously, we are not on the same page. A hold point can be issued to any position on the airport where ATC envisions a traffic concern such as a truck crossing road or runway not in use where caution is advised. This is not the same as what you are stressing which is a Runway Holding Position. These consist of four yellow lines, two solid and two dashed,spaced six or twelve inches apart, and extending across the width of the taxiway or runway. The solid lines are always on the side where the aircraft must hold. To cross a position so marked, a clearance is required before further taxi. $\endgroup$ – Loren Apr 26 '18 at 16:26

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