The principal source of data on air travel is the Civil Aviation Authority (CAA). They have three data sources that may be relevant:
The first two sources provide data on the number of passengers using airports, the routes they use, cargo and mail handled and aircraft movements. Data for the most recent years can be downloaded from the CAA's website. Published reports for recent and earlier years are available for purchase.
The CAA's passenger survey contains much rich data on the characteristics of air passengers including their ultimate origin/destination and surface access mode. Reports are produced periodically on the characteristics of passengers at the surveyed Scottish airports. The database is available for purchase from the CAA's agents. Specific cross-tabs on the data can be commissioned.
Timetables for scheduled air services are readily available from airlines and airports. The Official Airline Guide (OAG) summarises all scheduled air services and can be a useful source for examining how service patterns have developed over time. Data on charter/inclusive tour services and freight-only services is usually available from operators and airports.
Further high-level data is available in Scottish Transport Statistics.