Over 4.2 million new transcripts are now available in TheGenealogist’s ORB collection. With over 11 million records online, this is the largest collection of searchable AIR 27 records. The originals are at the UK National Archives.
ORBs are made up of Form 540 – Summary of Events (the majority), and Form 541 – Detail of Work Carried Out to provide an accurate record of the functioning of the Royal Air Force and some Dominion and Allied squadrons under the command of the British. Appendices that go along with these documents give many statistical details as well as “Secret Orders.”
Events records are arranged by squadron number and date and time of sortie or flight.
The UK National Archives has its own access to some of these records at https://www.nationalarchives.gov.uk/help-with-your-research/research-guides/royal-air-force-operations-record-books-1911-1963/. Ancestry also has an ORB collection with 751,751 records. Is the way records are counted is the same at the various sources?
UPDATE
Information from TheGenealogist
“We are very close to having indexed all of the records, but already have all the images online to browse. I know that some magazines state that Ancestry has completed the release but this appears to be for browseable images only (we also have the complete browseable images). TheGenealogist is by far the largest collection of searchable AIR27 records online with over 11 million versus Ancestry’s at just over 750,000 (according to their Card Catalogue).”