How common was it for USAAF aircrews to swap airplanes?

Question

My (rather novice) understanding of U.S. Army Air Force (USAAF) practices during WWII (and afterwards in the U.S. Air Force) is that aircrews were assigned specific airplanes, and that if an aircrew's airplane was inoperable then its missions would typically have been assigned to a different aircrew with an operable airplane. Is my understanding wrong? If not wrong, then were these practices a matter of policy? Tradition? How often were they counteracted, and for what sorts of reasons?

Context:

I'm trying to learn as much as I can about this crash in October 1942. All USAAF records of said crash indicate that the airplane involved was a B-24D designated 41-23712 (nickname "Ambrose" [or "Ambros"]). Any related material you find in a cursory search of the internet regarding this crash is almost certainly already known to me. A letter dated 1993 indicates...

...retired M/Sgt. [name redacted] was a ground Crew Chief on one of the 330th.B.S. planes. He remembered Capt. Williams and told me that his regular plane was "AMBROSE" serial No 41-23712-R and was under repair and the only other plane available for their mission was, "READY TEDDY" serial No 41-23721, so that was the plane they crashed in.

This is supported by the pilot's daughter, who was given keys found with her father's body in the wreckage--those keys have a tag on them stamped with:

B-24D
23721
#516

This is a surprise to me given my understanding described above. Hence this question.

Answer 1

I know nothing about your specific context, but the policies in all armed forces around the world (including USAAF) has been the same as you describe, except emergencies.

E.g., Ambrose is damaged but Ready Teddy is not, and the former's crew is intact while the latter's crew is not (e.g., some of them are wounded), then, naturally, the "A" crew might take over the Ready Teddy for one or more missions (provided the planes are of the same type, which is the case in your context).

The same for, say, tanks &c.

PS. There are two conflicting priorities:

1. Having as many operational units as possible (this suggests combining all available people and equipment regardless of their mutual familiarity)
2. Having efficient and effective units (this suggests keeping teems and equipment together)

The balance between these determines the action.

Answer 2

Reading through the RAF Operational Record Books (ORBs) of RAF Coastal Command Liberators based nearby at Beaulieu, it seems that it depends to some degree on the Squadron. Also remember that on anti-submarine patrols the sorties were by individual aircraft not whole squadrons, so squadrons generally had a handful of aircraft kept at readiness and rotated other aircraft in when one of the operationally active aircraft needed maintenance. Obviously this doesn't tend to the idea of having crews for certain aircraft as otherwise certain crews would be doing all the work until their aircraft needed maintenance. You could do with looking at the 330th BS ORB or whatever they are called by USAAF units. If that doesn't help you might look up the airfield logbook for RAF Holmsley South was coded AAF-455 but that was in 1944, so I expect you'd need to look at the RAF one at The National Archives in Kew, if you are lucky the aircraft.

A source from a booklet (unreferenced, but possibly the RAF Holmsley South airfield logbook) states the following: ... four Liberators set off from Holmsley at 07:20hrs on a navigational exercise covering the English Channel, the Bristol Channel and Southern Ireland. At 16:20hrs B/330, Captain W.J. Williams, crashed in Porlock Bay. only Staff Sergeant W.B. Thorpe survived out of the twelve crew members ... This indicates that the Liberator in question carried the code letter B. Codes O, Q, S & U apparently come from the same source. Potentially as the Liberators were attached to 19 Group (Coastal Command) they may have filled in RAF Squadron ORBs, though I can't see anything. There is a pic of "Hot Stuff" (41-23728) on patrol on 31 Oct 1942 in olive drab, without any coding, but a couple of pics in 1943 show coding clearly on tail planes such as A on The Duchess/Evelyn (41-24147) and E on Pudgy (42-40613). Hope that is of some use.