The use of an ATR 42 on the IOM-LCY route may be a temporary measure while the final ATR 72-500 is being repainted. However, the aircraft choice is a commercial decision for Aer Arann in terms of do the loads on IOM-LCY justify the deployment of an ATR 72 when it could be used more profitably elsewhere. The other consideration is whether or not the aircraft on the route meet the expectations of the customer. Does the average traveller between IOM and LCY mind whether it's a new ATR 72-500 or an older ATR 42-300??
In the end it will come down to a commercial decision for Paul Schütz and his commerical team.
Regards,
P2C