Approximately what proportion of the year does a 737 in the Ryanair fleet spend unavailable for commercial use ?
By this, I mean time spent undergoing any form of maintenance or any other time when flying passengers is not possible. I count time spent on the ground on a Wednesday in late January not undergoing maintenance as being available for commercial use.
In particular, I'm interested to know what proportion of the year a FR 737 spends on the ground when it's neither being used for flying passengers for profit nor undergoing any kind of inspection / maintenance or other commercially useful duties. This number is probably rather more important when judging FR's capacity to make optimal use of its fleet rather than just time in the air. Presumably it's better to have an aircraft doing naff all in January, than grounded for maintenance in July...