[Observer1940]

Hello Ross

"F 9" Cause is "Unknown or not yet determined" by the RAF.

This would have definitely been referred to the AIB. Because if the RAF had come to a finding finally, they would have struck "F 9" out and replaced it with another RAF Cause grouping, although many accidents were still referred to the AIB anyway for various reasons, including epidemic accidents for opinion and further investigation, or advice.

The Air Ministry / RAF Secretariat S.4. (S.4. was a Statistics Branch) compiling RAF Flying Accident Statistical Reports, on a Monthly Review basis. I suspect the RAF Flying Accident Cards were originally held in the S.4. Branch, or S.4. had access to the AM 1180 Cards.

The AIB had their own separate Card indexing system in WW 2 beginning with a 'W' or a 'U' numbered index with a filing reference and cross reference to the RAF Accident File number usually beginning with an A (but sometimes a 'P'), as I managed to get an AIB 'U' Index Card.

Unfortunately, the AIB were allowed to destroy their correspondence ten years after creation, according to a post-war Destruction Schedule I have found. It seems that many AIB reports were destroyed by 1950, which is a shame because an A.I.B. Inspector's opinion took precedence at an RAF Court of Inquiry, according to RAF King's Regs.

Back to the Beaufighter, the comments about instrument, loss of control (which I suspected in my last post) was either possibly an RAF suggestion as to the the cause (because the RAF were saying "undetermined", or likely what the AIB suggested as possible causes or opinions.

Mark