Methusalah recommended "Beyond the Blue Horizon" - quite right, I've read it four times now and it keeps on getting better.
More: (Thinks... you're gonna be quite busy reading for a while there, Big Chief...)
Ken Follett's "Night Over Water" - not totally about the aeroplane, but very nice Pan Am Clipper (Boeing 314, that is...) background and very well researched.
"The Wrong Side of The Sky", "Judas Country" and "Shooting Script", all by Gavin Lyall.
Another all-time classic, sometimes mentioned with almost as much reverence as "Fate is the Hunter", is Guy Murchie's beautiful "Song of the Sky".
Not fiction this one, but cracking good read anyway, full of epic tales of derring-do... Sir Gordon Taylor's autobiography "The Sky Beyond". (How about the time when, crossing the Tasman Sea in a Fokker Trimotor, they had to shut down one of the wing engines and later on, the other wing motor starts losing oil like it's going outta fashion. Since the only other alternative is going swimming, your man decides to go out and get the oil from the shut-down one and pour it into the other... Don't believe it? Read the book!)
If you have trouble locating any of these, try The Aviation Bookshop, 656 Holloway Road, London N19 3PD, phone 0171 272 3630. Better yet, go and spend a week or three in there...
Happy reading. If you try any of the above and enjoy them, let me know.