I would think that the reason for the bankruptcy would be germane. If it's the result of a failed business venture, it shouldn't be a problem. After all, the person in question is seeking salaried employment which is what English courts require him/her to do to salvage the financial situation. An airline will be more concerned with flying abilities than financial acumen.
On the other hand, if the subject had used bankruptcy as a cynical ploy to avoid repaying, for example, a student loan then any potential employer might have concerns about his/her probity.
Whether to admit bankruptcy to a potential employer must be a personal decision, bearing in mind that most contracts of employment these days seem to have embedded provisos about failure to disclose pertinent information.
Good luck, in any case.