Aviation > Pilot/Controller Forum

Maximum length/number of instructions/clearances from ATC?


A question for Controllers and Pilots...

Is there a definitive maximum on the number of instructions that can be issued by ATC to pilots that must be read back?

For example, ATC says "Lear 2-8 Bravo Hotel, descend to 3000, turn left to heading 2-4-0, and reduce speed to 1-8-0" would count as three "instructions" for the purpose of my question.

I'm curious as to how many "instructions" a pilot may be required to briefly memorize, read back correctly, then comply with strictly from memory.

I've listened to some pretty "lengthy" instructions/clearances and was wondering if there's a defined regulatory "limit" as to how many crucial pieces of information can be issued (verbally) and memorized before the limitations of the human mind may corrupt the information.

Thanks in advance.

As far as I know there is no regulatory limit to the "number of instructions" that can be given in one transmission. The most lengthy set of instructions from ATC is typically an IFR clearance, where a pilot is given a clearance limit, a route to follow (which can in itself be many instructions), maybe a departure heading and altitude, a departure control frequency, a squawk code, maybe a void time, and possibly a number of other things, all in a single transmission.  But the pilot is prepared for this (he just ask for it!), and is usually on the ground with pen and paper in hand ready to copy it all down.

I think most controllers will limit the number of instructions they give pilots once they are airborne to three or four at the most.  They don't want to have to repeat themselves either, so there is no point in overrunning a pilot's short-term memory!  Something like a heading, altitude and speed change is just normal and expected and not a problem in a single transmission.  For something more complicated, like an airborne full-route clearance, a controller would typically say something like "Lear 2 8 Bravo Hotel, I have a reroute for you, advise when ready to copy" - and that's your signal to get your pen ready to copy a bunch of stuff!

Thanks for the reply!

In training, I was told to issue only about 3 instructions at a time. No regulatory requirement, just the amount of information the brain can handle at one time.


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