ATC IssuesA place where pilots may enter the 'lions den' that is Air Traffic Control in complete safety and find out the answers to all those obscure topics which you always wanted to know the answer to but were afraid to ask.
Seems like plain English to me. I don't think CAP413 is supposed to be inclusive of all necessary R/T to cover all eventualities. I work in ATSOCAS land and my unit has an excellent working relationship with a wide spectrum of military agencies. In the case mentioned.....if you say that you will be operating "not above" 3000 feet [for example] ....it may permit his/her other traffic to operate above you without interference, because your intentions are known. Perhaps the controller was asking a question rather than issuing an instruction....if what you wrote is accurate. In my varied experience "not above" clearances [although this particular case was not a clearance] are not unusual in the UK and so the terminology used should not be completely alien.
Does anyone know the reasoning behind using "not above" rather than "or below"?
Where I come from the standrad phraseology seems to be "1500 feet or below", but in the UK it's "not above 1500 feet". I'm just thinking that, from my untrained point of view, it seems more logical to use "or below" since the risks of missing part of the transmission are less. E.g. Controller transmits "1500 feet or below", pilot hears, "1500 feet", in that case the only think that you miss is that the pilot maintains 1500, rather than the block of 1500 or below.
But if the controller transmits "not above 1500 feet", and the pilot hears that as "above 1500 feet", the meaing of the transmission is reversed.
Now granted with proper readbacks and hearbacks the above should never be able to happen, but I'm just trying to see if there's any advantage to using "not above" rather than "or below" style phraseology. Once again I'm not an ATCO or a pilot (even though I hope I will one day make it to become a validated ATCO), but from my perspective it seems more safe to use a positive "or below" clearane rather than a "negative" "not above" clearance.
Maybe he was asking your height from sea level not the height above from the ground level..
I am currently at flight school We use something like that when we are flying Vfr XCountry flights.. Max alt: 1500 AGL (above ground level) so sometimes altitude is 3000 ft but still 1500 ft above ground..
For military controllers, its not uncommon for them to ask a light ac on a BS to request an Altitude or height not above, so they are given full SA. They will then request you fly not above it if they need co-ordination with other ac. Simple. It says nothing about taking 1000' on charlie, yet i've heard civvy atco's request it on co-ordination regularly.