I've often wondered, what is considered a reasonable response time respond verbally to a communication from an ATC controller, and also to begin the course or altitude change commanded? Also, how often do pilots have to request a repitition of the ATC command?Thanks in advance,Noel

In busy Class B airspace the response is expected within seconds for the most part. Much longer than 5 seconds and the controller is likely to query you again. I couldn't put a number on how often people use "say again" to have something repeated but it's not unusual. Your response to actually executing the command ATC gave should happen pretty much right away, otherwise don't accept the instruction.

Fly first, communicate second.

I've often wondered, what is considered a reasonable response time respond verbally to a communication from an ATC controller, and also to begin the course or altitude change commanded? Also, how often do pilots have to request a repitition of the ATC command?

As quickly as possible, but if a controller tells you to "turn right heading 320", always act then respond. So in other words turn right heading 320 and then acknowledge ATC.Hope this helps,

You should respond right away. If ATC issues a heading, turn to it right away.

Fly first, communicate second.

Or at the same time ;)

You should respond right away. If ATC issues a heading, turn to it right away.Or at the same time ;)

Prorities are:1) Fly the aircraft2) Navigate the aircraft3) Communicate from the aircraft

Well if you aren't responding in 5 seconds I'll get on your case... Or just go to the next aircraft.It's not that hard to combine all those three into oneAnyway, we talking real world or like vatsim? Because on vatsim everything moves slower... both the controllers and pilots sometimes don't know what's going on.I'm saying IRL...90% of the guys I deal with are professional combine the three items. Obviously student pilots will need more time. If I'm not getting a response within 5-10 from a student I'll just issue the instruction again. Ten seconds is quite a while when you're moving at 120 kts.

and also to begin the course or altitude change commanded?

By default, as said before, you are expected to carry out the action the moment you receive it. However there are instances where ATC can use terminology such as "pilot's discretion" which means you can begin the climb to a new flight level when you are ready to do so (however once you vacate a flight level you cannot return to it, so this only gives you permission to climb/descend at your convenience). Another is "when able" which means you don't have to comply immediately if you are busy with something else, but at the very first opportunity you are required to comply.

Also, how often do pilots have to request a repitition of the ATC command?

I don't know how often but it definitely happens, and you should never be worried about sounding like a newbie or anything for doing it. If you really can't bring yourself to admit you heard wrong, then at least read back what you think you heard, and the controller will correct you if you got it wrong. But then, the controller may not catch your mistake of your readback is close but not fully accurate, so you're just opening up a window for trouble. Best to just reply with "Say again, slowly". No shame at all in it.Anyways I'm basing all this of real-world ATC but that's a good base IMO for Flight Sim and VATSIM.I highly recommend taking these free safety courses from the AOPA - you can get a free membership to access them. One includes a course on radio communication. I'm working through them now and they are excellent!

Aviate..Navigate..Communicate..That's how I was taught here in the U.K.As soon as you acknowledge an instruction ATC will expect you to action it within a few seconds. You should NOT act on an instruction until acknowledging it in case you have mis-heard the initial instruction.

Thank you all for these insights. It adds some meaning to my virtual experience! I think from all that's been presented, probably will adopt the practice of replying to ATC immediately, but act only after acknowledging my reply. I would think that although the controller would like you to act immediately to make their job easier, I can see why it would be a prudent practice to try to make sure you heard the command correctly before changing course to avert the most severe collision risk that could come from rapidly making a wrong course/elevation change.Thanks for the tip on the AOPA's free lessons. I'll check it out . . .

...but act only after acknowledging my reply.

Remember it's fly first, not communicate. If you get an instruction "United 437 turn right 190" then begin the right turn and then radio back "right 190, 437". Only avoid making an immediate action before replying to ATC if you did not understand them, not all the time.

Remember it's fly first, not communicate. If you get an instruction "United 437 turn right 190" then begin the right turn and then radio back "right 190, 437". Only avoid making an immediate action before replying to ATC if you did not understand them, not all the time.

What?It's just as well this is a flight SIM forum :(

What what? My crude and inaccurate example of ATC speak or the fact that you should initiate instructions (that you understand) before radioing back? As far as I understand, ATC tells you to do something you do it. You don't wait until you can radio them back - which in some cases may not be immediately as other traffic jumps on the channel. A read back is not to tell ATC you are doing something (most of the time they can see you carrying out their instructions on their scopes) but to make sure you did indeed hear them correctly.