I suspect, to an extent, Aberdeen Rapid Transit would provide the direct public transport link between City Centre (and other locations on the Portlethen-Craibstone route) and the Airport. Otherwise you're getting one of the other 757 bus services, a taxi or just park and fly. Or if you do have time to travel slowly, get a train to Dyce and wait on the local bus.
Another general point - there are portions of the day in which current rail network operating times would not enable access to airport in time for early morning flights, nor be available for when you get off a plane after say 10/1030pm. I'm not sure as a percentage how many flights/passengers that is, however given many AM ones may be business-related, potentially are trips of higher-value.
Re. Edinburgh Airport, there was a plan to put an underground station at the Airport which both Fife line and Glasgow services (via Almond Chord) could access. This was quashed by the SNP government in favour of Edinburgh Trams project. Rest is history. Fundamentally, tram service not a bad option for local travel, but for more regional/strategic travel, Edinburgh Airport rail station would have been ideal.
We seem in this country to be able give direct rail connections to non-major airports, i.e.
- Prestwick
- Proximity of rail station to terminal is excellent, however very few flights, many of which take-off and land either early morning or late at night. Trains don't operate on Ayr line that get you in time for early AM check in; or your flight arrives after last trains. So air passengers don't get the benefit.
- Inverness
- Reasonably sensible as rail line is...sort of close. However it is a 20 minute walk to the terminal, which feels a bit long to be convenient. Don't believe there is a shuttle bus. If travelling from Inverness City Centre, you could get the bus from the same location and it will take you up to the terminal.
- Aberdeen
- As somebody said, it was decided to move the terminal away from the rail station side. I like the idea of the very long travelator under the airport to the rail station!
- Edinburgh
- As i say above, could have had an under-airport station linking both Glasgow via Almond Chord and Fife line. Removed the need to change over at Haymarket or at Gateway. Similar situation to Dyce, you need to transfer, ableit Tram a more viable option than what's available in Aberdeen.
- I'd be interested to know the impact having a direct Glasgow-Edinburgh Airport underground station would have on Glasgow airport. Arguably you could arrive in Edinburgh airport and hop on a train that gets you into Glasgow City Centre in ~35/40mins.
- Glasgow
- Lack of fixed rail link to airport has been discussed to death.