They fly by commercial flights, normally First Class.
My wife in the innocence of youth once asked Nathan Knorr why he traveled First Class and she lived to tell the tale. His answer was well rehearsed, that is that people expected the head of a huge Organization to travel in such a manner and it would not bring dignity to the Organization not to do so!
I think she would have respected him more if he had just told her to "bugger off you little peasant" and been honest about it. :)
HS