About Edinburgh Airport
Flights to Edinburgh come into Edinburgh Airport, which is the busiest airport in Scotland and the 6th busiest in the UK, with 11.13 million passengers passing through in 2015 (that’s an average of 30,495 air passengers a day).
The airport hosts over 313 flights a day, with 32 airlines serving 173 routes to 122 destinations. No matter where you are in the world, flying to Edinburgh has never been so easy.
A plane starts the day at the airport, does an even number of flights back and forth, and then one last flight and ends it at another airport. Repeat the next day but in reverse.
The way I described it, there would be an odd number of flights every day, so the average will also be odd.
Imagine there was only one flight. Day 1 it leaves Edinburgh and lands at Heathrow. Day 2 it leaves Heathrow and lands back in Edinburgh. Then repeat again. There is exactly one flight every day, so the average is odd.
Every plane lands and starts, that are 2 fights. Any daily etc. irregularities cancel out over a year. What could still happen is something like a plane landing on 31.12. but not taking off before it is 01.01.
Considering that... alright, it does not need to be an even number. And those are exact numbers, not averages.