What expenses can they, or the airline , claim to have incurred if the individual hadn't even started training, the next candidates interview? Nah ! and surely the cost of ones assessment sim-ride should be borne by the company, or do they think the candidate (successful or not) should be paying? Anyhow, 10K is a big p1sstake.Even if they say it is how much they would have earned courtesy of your labour for 1year, Hey, they are going to earn it anyhow with whoever takes the position instead, so what have they lost ?
Having previously applied for this position I can confirm they contribute not one €cent to expenses incurred in flying to BRU for the interview
( which in any case I failed

) nor indeed make any contribution to the cost of the hotel/hire car etc.
Neither was it mentioned to me before accepting the invitation that I would be expected to sign a bond on a type I was rated and current on, something neither I , nor my bank

would have agreed to.
Instead of spending time/money on solicitors, they would be better using their efforts to see why people don't stick around/even show up, if they find something else.
There is a clear message there, but they don't want to hear it.