Read the book by Amiee Brat: Glamor and turbulence
, it's a biography from a Pan Am flight attendant.
A big thing that led to the downfall of Pan Am was the fact that they operated so many 747s, and didn't have the money to keep them running.
Deregulation was a big factor. After deregulation, airlines like American, Unt=ited, Delta, and even Continental were awarded international routes where Pan Am didn't have the compition before.
Now that hurt Pan Am because of there lack oif a domestic market here in the United States. A passenger going from, oh lets say, Tulsa couldn't get to London very easily, on Pan Am. After Deregulation, a passenger could fly on Delta, American, United, Continetal, TWA and so on.
Maintence probles with there 747s were a big factor.
Flying 747s from JFK to San Juan wasn't making any money.
Trying to be too good.
I remember reading in that book that in 1982, one extra lemmon would cost Pan Am $15
Hope that Helps