Must be lots of snow or ice.
LGW flying in circles at the moment and indefinite delays on several flights.
From their twitter feed
https://twitter.com/belfastairport
MoreUpdate 18:15 Our snow teams are continuing to clear snow from the runways and aprons and we are aiming to reopen shortly. Delays and disruption to flights can be expected because of this so please check with your airline for latest flight updates.