I have heard that you can switch to the tower frequency once you are at the runway hold line and are ready for takeoff without getting permission from ground control to switch frequencies. Is this always true or does the procedure vary for different airports?

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    $\begingroup$ As a general rule, don't leave a frequency unless you ask first or are told to do so. There are very few exceptions to this rule of thumb. $\endgroup$ – acpilot May 10 '18 at 15:49
  • $\begingroup$ Were you given instructions like "Taxi to two-four via golf-delta, contact tower on 122.7"? Usually following that type of instruction I stay on ground until reaching the hold point then switch over to tower and announce position and intentions. $\endgroup$ – Ron Beyer May 10 '18 at 15:54
  • $\begingroup$ @Ron Beyer: I haven't taken off from a towered airport yet which is why I am asking. Is that how ground usually gives instructions, the route then the tower frequency? $\endgroup$ – DLH May 10 '18 at 15:58
  • $\begingroup$ @DLH It depends on the airport, the ones I fly out of are not all that complicated taxi-wise, but in my experience yes, it is the taxi instructions followed by who to contact next. The important thing is to not change frequencies while under the control of ground. And if in doubt, ask (for everything, including if you don't remember if you can cross that taxiway/runway/hold line). Sometimes they won't tell me to contact tower if they are having me hold short somewhere else, like the ILS hold line. $\endgroup$ – Ron Beyer May 10 '18 at 16:02
  • $\begingroup$ Yes - and make sure you have an airport diagram pulled out, the routing can be tricky. Don't cross any runways unless you have been told you are clear to cross them. $\endgroup$ – CrossRoads May 10 '18 at 16:02

While I acknowledge the answer by GdD to not change frequencies until instructed, that is at odds with my experience.

When I call Ground, then request and receive taxi-instructions, I stay with Ground to the runway hold short line. I've never had Ground give me an explicit instruction to switch to Tower.

When I start my run-up checks, I switch to Tower (unprompted) to start hearing what is happening in the airspace. When my run-up is complete, I call Tower with a "ready for takeoff".

I've never had Ground, Tower, or any Instructor tell me differently. I've never observed another pilot wait for an explicit frequency change instruction from Ground, and I believe that is the way I was taught.

this only applies when you've taxied to the hold-short with Ground. If Ground tells you to switch earlier, do it. If you want to switch earlier, request it.

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    $\begingroup$ this is also my experience. $\endgroup$ – Erin Anne May 10 '18 at 19:52
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    $\begingroup$ This is how we do it at my home airport also. $\endgroup$ – PJNoes May 10 '18 at 21:17
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    $\begingroup$ Centennial airport near Denver (KAPA) is an exception. After run-up is complete, you contact Ground and they will let you know when to switch to the Tower. I learned to fly there and didn't know that this was the exception until getting corrected at a few other towered airports. If you look in the A/FD for Denver Centennial there is a note telling you this under communication notes at the end of the entry. $\endgroup$ – rmaddy May 11 '18 at 1:01
  • $\begingroup$ Do you really say Ready for take-off and not departure in the US? $\endgroup$ – Vladimir F May 11 '18 at 8:50
  • $\begingroup$ @VladimirF: While US phrasing does technically call for "ready for departure", at many small, low traffic airports, radio communication gets less formal, and admittedly, many people do say "ready for takeoff" even though they shouldn't. I've also heard "Ready to go", and a variety of other phrasing. $\endgroup$ – abelenky May 11 '18 at 15:38

I have found this AIM 4-3-14a which I believe answers my question:

AIM-4-3-14a: Pilots of departing aircraft should communicate with the control tower on the appropriate ground control/clearance delivery frequency prior to starting engines to receive engine start time, taxi and/or clearance information. Unless otherwise advised by the tower, remain on that frequency during taxiing and runup, then change to local control frequency when ready to request takeoff clearance

This seems to suggest that it is OK to switch to tower once you have completed the runup and are ready to takeoff at least in the US. Also interesting here is that it says that you should contact clearance/ground prior to starting your engine. I have never heard of that before.

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    $\begingroup$ "This seems to suggest that it is OK to switch to tower once you have completed the runup and are ready to takeoff at least in the US. " I don't think that is what it is suggesting, especially if you are flying VFR. It is saying to contact tower on the appropriate ground control frequency. From then on "tower" is referring to the ground control frequency, not the frequency you get your take-off clearance from (local control frequency). The AIM writes this very cryptically. $\endgroup$ – Ron Beyer May 10 '18 at 19:51
  • $\begingroup$ @RonBeyer - I'm not seeing what's different in your comment vs. DLH's answer. In both cases, you're staying on ground control frequency until after runup, then switching to local control frequency when ready to request takeoff clearance. I think the point DLH is making here is that there's no need to make a specific request to change frequencies, it's part of the procedure post-runup. $\endgroup$ – T.J. Crowder May 11 '18 at 12:22
  • $\begingroup$ @T.J.Crowder The difference is that you are assuming that the run-up takes place at the end of the active runway or on the taxiway just before you need to switch. My experience at towered (Class-C) airports is that they really do not want you to do that. Either they have designated run-up areas or they assume you will be ready to go when you call ground for your taxi instructions. Running up at the end of the active with traffic behind you will not make you any friends at a busy airport. $\endgroup$ – Ron Beyer May 11 '18 at 12:53
  • $\begingroup$ @RonBeyer - If the runup is in a designated runup area, clearly you're going to taxi from there to the runway, so you're going to stay on the ground frequency per the above. I don't think DLH was suggesting otherwise. Hope not, anyway. $\endgroup$ – T.J. Crowder May 11 '18 at 13:15
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    $\begingroup$ @T.J. Crowder: I took the regulation to say that when you are ready to take-off you can switch to tower unprompted which means having performed your run-up and taxied to the hold short line. $\endgroup$ – DLH May 11 '18 at 15:25

If you are under control of ground you only switch to another frequency when directed, or are granted permission. They'll tell you "Contact tower on xxx.yy", for example. You might ask to change, say you only have one radio and you want the latest ATIS, in which case you request to change, and wait until they give you positive indication that is okay. You may need to shut down your avionics to start up your engine, especially common in light singles, in which case you ask permission for that as well.

If ground goes off of the air or you have trouble contacting them you can change to a different frequency for a radio check, or if there's some sort of emergency requiring changing frequencies to resolve then do so, it's hard to think of a realistic case for that; if you have an emergency on the ground then ground is best placed to help you.


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