I love William Langewiesche's work.
His book Inside the Sky: A Meditation on Flight, inspired and educated me while I was working on various flight ratings, and I still learn from it when I re-read it. His articles have appeared in the Atlantic Monthly for many years, and I very strongly recommend his AM articles on flight (many of which appear in this book) to anyone interested in aviation, laypersons and pilots alike. Additionally, his reporting on the war in Iraq has been excellent and beautifully composed, and he's a wonderful general subject and foreign policy writer, as well. The Atlantic Monthly publishes their most recent archives online for free- please take a look when you've got the time. One of the best articles I've ever read on flight, The Turn, is a paid-subscription-only article on the web site, but is printed in full in the book you see here. Same with The Lessons of ValuJet 592, possibly the best summary of an aviation disaster I've ever read- he does admirable justice to the complexity of the circumstances leading to an airline crash, and recognizes the errors inherent to human works.
For his entire Atlantic Monthly collection, click here.
Specific articles I've enjoyed that are available online for no charge:
Aviation
Columbia's Last Flight
The Crash of EgyptAir 990 (first paragraph only, sorry)
Iraq
Foreign Affairs
Other