Peter wrote:
So “to” is used with altitude but not FL?
A FL is an absolute value, while altitude without the preposition could mean either descending 3,000 feet (say from 5,000 to 2,000 feet) rather than a specific altitude with a QNH or QFE.
while altitude without the preposition could mean either descending 3,000 feet (say from 5,000 to 2,000 feet) rather than a specific altitude
Sure, but I always thought it was one of the cornerstones of aviation that relative climbs or descents were absolutely nonexistent.
Most ATC just use “descend 5000 feet”.
Peter wrote:
Most ATC just use “descend 5000 feet”.
I must listen out for this (it obviously doesn’t penetrate far into my brain!)
I always respond “descend to altitude 5000 feet”, but maybe I just don’t hear, or internalise, exactly what they say.
A frivolous discussion has turned into a valuable discussion! 
A number of CRM cases where poor ATC on level/altitude changes resulted in CAT fatalities. UK IFR ATC standards is actually something the UK should be proud of.
I could no doubt dig up way more of my videos than anybody would want to watch, but here is a good recent one
which will likely show both examples. This video was “cut around the ATC calls”. Notably listen around and after 17:00 for examples of what I say above. Earlier, London Control, they seem to use “to” but it is very short and barely perceptible.
I have many more but it would take a bit of time to go through them, especially if you want altitude instructions rather than FL instructions. The place to look is after departure and before arrival, obviously, and skip videos which contain music because they won’t have ATC calls (if I am flying with passengers I don’t usually record sound, so I use music; also editing around ATC calls takes more time).
UK IFR ATC standards is actually something the UK should be proud of.
I agree.
However I cannot believe any pilot, and most definitely any pilot who has an IR and does any flying at all, would think a climb or descend instruction could possibly be relative.
RobertL18C wrote:
A FL is an absolute value, while altitude without the preposition could mean either descending 3,000 feet (say from 5,000 to 2,000 feet) rather than a specific altitude with a QNH or QFE.
I have never ever experienced, heard or read about ATC issuing relative altitude changes. Has that actually happened to you?
Peter wrote:
they seem to use “to” but it is very short and barely perceptible.
The one just after 5:00 has a very definite “to altitude” in my opinion, which is correct.
Edited to say, I mean the ATC is correct, not I am correct
Listen to the rest of the video
“To” is very rarely used.
Another thing is that London Control clearly speak much slower to GA pilots.
Close to my home there is an Air/Ground operator who is always very technically correct and a very nice bloke to go with it.
However one summer I was inbound with a chinese student and the A/G operator read back numbers
WUN, TOO, TREE, FOWER, FIFE etc
And the kid goes WTF is he on about can’t he speak english?
Listen to the rest of the video
It would be lovely to have time
Another thing is that London Control clearly speak much slower to GA pilots.
I have never noticed that.
