What sort of aircraft group is this? Benefits in kind taxation is only applicable to employees. I really don't understand this scenario and cannot see any problem. There may be other taxation pitfalls but I can't see how BiK is one of them.
If a company wants to "give away" goods/services to its customers then that is disallowable for corporation tax and would probably attract VAT anyway (i.e. pay over the VAT that would have been collected had the customer paid a market price).
A company pays corporation tax on its profits. Employees pay benefit in kind tax (income tax) on any benefit received from their employer. A customer is not a employee.
Cheers
Whirls