I had a friend years back who developed an extreme fear of flying after being on a plane that nearly crashed during take off. Before that he was an avid flyer basically every day off work he got he was on a plane somewhere, that ended immediately after that experience.
Problem was he had a job that required him to meet clients all over Europe. His solution was to fly always the day before he was due to be somewhere so he could get absolutely shitfaced before take off, he'd do bumps of ketamine just before airport control and would spent the whole flight ordering whiskey.
Anyway point being I see why Bergkamp would simply refuse, not a solution for everyone and phobias can be crippling for some.