Darts current share price is undoubtedly lower than it was but its pretty much in line with the falls across the sector (RYR and TUI are the exceptions). If you take todays price (BBC) against the 12 month high and express it as a percentage here are the results:
Ryanair 88%
TUI 80%
IAG 73%
Flybe 71%
Easyjet 69%
Dart 68%
T Cook 63%
Of course stats over 12 months can hide an awful lot as they are but a snapshot in time - the only point I would say with some certainty is that the UK (and Irish) air travel companies have taken a hit recently