FOs [non type rated] can expect to cough up £12000 which will be repaid monthly over three years. There is a notional interest payment made as well calculated using bank base rate. If you leave before this time then the repayments stop. Air UK [as was] use to operate something similar years ago.
Those with the type rating have been "charged" for the line training which always struck me as being a bit cheeky. This covers the cost of training - so they say. Just another way to help the training budget and spead the cost forward.
DECs have signed an old fashioned style bond of £12k over 3 years which is the fair way.
As you can see, the more experienced you are, the more favourable the deal. Simple market forces at the end of the day.
