My take on this "old chestnut"
Over a forty plus year career I experienced more diversions due to blocked runways than due to weather. Most fuel policies are drafted in terms of what you can do/not do depending on how good the weather is. Now, when the weather forecast is good, then most aircraft tend towards carrying minimum legal fuel loads - couple this with much tighter landing spacings and you are now all set up for massive delays if a lander bursts a tyre or requires ATC to do a runway inspection etc.
Take for an example Gatwick (possibly the most busy, single runway, international airport in the world) - a 15 minute runway closure will typically result in up to 10 aircraft holding most of which will probably be carrying the same near alternate fuel! A situation that could so easily turn sour.
Last edited by Meikleour; 19th May 2018 at 11:34.
Reason: typo