some new Canadian phraseology has just been put in place, it's scary and it's going to cause some "deals" real soon. you can mark my words.
we will use this example: BYWQ is 45 NM from dest level at eight thousand. he will enter terminal airspace 35NM from dest and as per a agreement all aircraft will be cleared to 7000' entering terminal airspace. they don't have to be level, just have 7000' as there cleared too alt.
the old way would be "BYWQ, maintain seven thousand, descent at your discretion/pilots discretion". I'd say that's pretty clear that his cleared alt is 7000' and he can descend from 8000' to 7000' whenever he wants.
the 2 options for the new way:
A. which is not so bad but wordy "BYWQ, when ready descend and maintain seven thousand" pretty clear just old habits die hard, hence it's hard to say when you've done it the other way a million times.
B. which is going to cause some deals "BYWQ, when ready descend seven thousand" correct phraseology is to say it just like that without a "to" in between descend and the cleared alt. and we are not required to say "maintain"
all 3 of those clearances mean the pilot can start down at anytime and his cleared alt is 7000'. if you look at the 3rd one though it would be easy for a pilot to think he has to descend 7000'; 8000'-7000'=1000' which is more than likely below a min safe alt. in the situation above if the aircraft is given "BYWQ, descend seven thousand" when he is 40NM out and a read back is received (but the pilot thinks he's cleared to descend 7000' aka1000'), then the aircraft starts descent(say 1000'/min). if the aircraft is now switched to terminals freq and he dials up the wrong freq and has to come back to en route to get the right one or terminal is busy and he can't check in for 2 min... well he's going to blow his alt and theres a good chance there is a plane around him that he may tango with.
even worse is if I'm climbing a guy through him, aka head to head and I'm going to force vertical to happen faster i would now say something like this "BYWQ, traffic 12 o'clock, two zero miles, opposite direction, metro, through seven thousand for one five thousand, descend seven thousand now" I'm thinking I'll split the diff and have the climber through 8500' and BYWQ through 7500' in about a min. BYWQ might think he's taking a "good run" at the climber and i need him to descend 7000' total (aka1000') right away to Miss him.
as always the suits know best about a job they are not trained to do. i control and think it's scary wording, but we will soon find out.