I did say on 18th April that I was slightly dubious as to the CAA data and that I was writing to them.
Well on Monday I received the following comprehensive reply - for which I'm very grateful:
"For reference, the Table 12 series relates to the passenger journey on the aircraft. Below are the definitions for Tables 12.2 and 12.3:
Table 12.2
(1) These figures are based on origin and destination of passengers as reported to UK airport authorities by UK and foreign airlines. Operators are required to report in respect of each service operated, the point of uplift and discharge of each passenger. The figures may not reflect a passenger's entire air journey: the point at which a passenger disembarks from a particular service may not represent his ultimate destination.
(2) Although operators are asked to report all passenger journeys, in some cases the actual point of uplift or discharge is not recorded. In such cases all passengers are allocated to the end point of the service, ie the aircraft's origin or ultimate destination. The figures in this table include all passengers carried on scheduled and chartered services excluding those carried on aircraft chartered by Government Departments.
(3) To avoid duplication passenger numbers are taken from one reporting airport in the pair. In the case of services at Heathrow, Gatwick, Stansted, Luton, Southend and London City, the London airport's reports are always used. In the case of routes not involving a London airport the passengers are reported by the lower alphabetical airport. Exceptionally where one report of the pair is not a full reporting airport, traffic is derived from the other airport's information, irrespective of alphabetical order.
Table 12.3
(1) These figures are based on origin and destination of passengers as reported to UK airport authorities by UK and foreign airlines. Operators are required to report in respect of each service operated, the point of uplift
and discharge of each passenger. The figures may not reflect a passenger's entire air journey: the point at which a passenger disembarks from a particular service may not represent his ultimate destination.
(2) Although operators are asked to report all passenger journeys, in some cases the actual point of uplift or discharge is not recorded. In such cases all passengers are allocated to the end point of the service, ie the aircraft's origin or ultimate destination. The figures in this table include all passengers carried on scheduled and chartered services excluding those carried on aircraft chartered by Government Departments.
(3) This table represents passenger traffic recorded by each reporting airport and includes both arriving and departing passengers, when both are reporting airports. The total traffic is therefore, only a measure of airport activity. Totals reported by airports over a given airport pair are not necessarily the same.
The mentioned route includes a mid-point, Manchester (ABZ-MAN-NQY). Table 12.2 is based on data reported by Aberdeen, which does not include a detailed breakdown of passengers disembarking at the mid-point (Manchester). Therefore, all passengers are allocated to the service’s end point, Newquay.
Table 12.3 includes figures reported by both airports:
Aberdeen - ABZ-NQY: 1,176 passengers
Newquay - NQY-ABZ: 276 passengers
Newquay Airport provides a more detailed passenger breakdown, with some passengers included in the Newquay-Manchester figure.
For reference, when comparing with Table 9, the figure for terminal passengers should be used.
Lastly, the PDF files contain notes concerning the data within them along with unabbreviated column titles, which may assist.
I hope you find this information helpful."