Ah, that great little word "maintain"
Over here on this small North American continent, the term "maintain" is used as the command instruction to change an altitude. In Blighty, the use is something totally different, and in fact could lead to a major misunderstanding.
Example in Canada: "ACA123, maintain 6000". ACA123 is cleared to 6000'
Example in UK: "ACA123 descend and maintain 6000". No major issue, ACA is still cleared to 6000' (albeit twice
)
Now, take this example:
Pilot: "ACA123 level 6000" (as they do here)
Canada ATC "ACA123 Roger" (or whatever)
UK ATC "ACA123
maintain" (as I used to do)
Now, the pilot as heard the command instruction "maintain". First though, listen out for the new altitude associated with the command "maintain"?
Hmmmmm......