For those newer members and our elder Alzheimers suffers a wee trip down memory laneMaster Aircrew did not begin life as NCOs. As the rank - and it is a rank, not a name - was part of the short-lived Aircrew rank system after the war, AMO A492/1946 stated that aircrew were not NCOs in the traditional sense - this was because the aim was to create an all-inclusive aircrew cadre which recognised that to attract volunteers in peacetime, there needed to be some status for non-commissioned aircrew. During the war, that had meant the creation of 'instant Sergeants' who an array of senior officers held were splendid aviating sorts, but utterly hopeless as NCOs because they had no experience and hadn't - because of little things like bombing Germany - had the chance to go on the requisite courses that 'proper' NCOs did.
Thus the Air Ministry, drawing upon some thinking/work by Sir John Slessor and Sir Sholto Douglas before him, came up with the plan that a separate aircrew cadre would be created. The non-commissioned aircrew (not non-commissioned officers) would muster separately on parade and have an entirely separate messing system. In essence, the RAF of the post-war era would have three tiers to it:
1. Officers (permanent career sorts)
3. NCOs and ORs.
The Americans might have called category 2 'Warrant Officers'... (and we could have had several Arrse threads on whether they ought to be saluted or not [for those who've been here long enough to recall that one...]). We didn't, of course, because a Warrant Officer is something different.
Thus, under the scheme, we had the following new ranks
The actual rank would depend upon the role of the aircrew - thus an aircraft like a Lincoln could have had Master Aircrew Biggles, Signaller II Marconi, Navigator IV Da Gama, Gunner III Vickers, Engineer I Brunel, Gunner II Lewis and Gunner IV Browning as its crew members.
The plan didn't work and was abolished. Aircrew IV-II became the rank of Sergeant Aircrew; Aircrew I became Flt Sgt Aircrew. Master Aircrew was retained as a rank.
AMO A492/1946, as well as stating that the Aircrew rank holders were not NCOs, recognised that it was necessary to have some equivalence with non-commissioned ranks for the purposes of pensions, allowances, etc. Thus MAcr was equivalent to a Warrant Officer; Aircrew I was a Flight Sgt, Aircrew II a Sergeant and Aircrew III and IV a Corporal.
This led the inimitable Basil Embry (his fellow VSOs were more than aware that he'd killed his guards with his bare hands before escaping from captivity in 1940 and going on to win a DFC as a 2* for his gallantry on operations, and thus regarded him...warily) complaining that the Air Force was offering would-be pilots the same pay as a bricklayer for rather more risk. Many of the senior officers thought it was a mad idea - but the reason was to avoid adopting the Canadian answer, which was to commission all aircrew.
The above system was so unpopular - Tedder, as CAS, asked the crew of a Hastings he was travelling on to observe Operation Plainfare what they thought of their new rank badges and was told 'they make bloody good jam jar labels. Sir' which rather confirmed his views on the matter.
By 1949 it was clear that the plan to reduce the officer:aircrew [remember, not NCOs] ratio was as rubbish as Embry and others had said it would be, and the Air Force Board threw its hands up, said 'sod it' and decided to commission all pilots and navigators.
However.... although the NCO rank badges and names returned - with Aircrew IV and III becoming equivalent to Sergeants - Master Aircrew survived as a separate rank. It did not revert to the old wartime rank of Warrant Officer. This doesn't mean that it hasn't become an NCO rank, but it wasn't simply a renaming of the WO rank for aircrew, since it originated from the 1946 scheme and was thus a new rank; it then survived the demise of the scheme in 1950, when the Sec of State for Air told parliament that the RAF had been aware for 'some time' that the scheme 'had not worked as well as had been hoped'.
(The above is a summary of the work of Wg Cdr Jeff Jefford in various locations - the RAF Historical Society Journal and his book on Observers and Navigators. Also a spot of work on my part involving, Flight editions from 1946, 1949 and 1950, a bit of Hansard and a bit of engagement with the original AMOs some years ago with some rather unclear hints as to where I found them).
By the by, there may be a complication with the WO1/WO2 argument in that there is one source, apparently drawing upon the archival records, which seems to suggest that the RAF didn't actually create the rank of WO1 in 1933 (instead having Warrant Officer and Warrant Officer, 2nd Class), hinting that the rank of WO1 has been assumed ever since, but didn't actually exist.... I'm rather sceptical as it's single source (at present) and would thus want to check that against the AMOs - so don't take that as gospel, merely as another possible bit of confusion to add to the proceedings.
The Original WO Thread
Which was a bugger to find tbh because there's a ton of later threads on the same frigging topic. Still, nice to see some old names and Avatars, incl. @Auld-Yin progenitor