(Sun, from aviation) A user's misconfiguration or misuse of a piece of software, producing apparently bug-like results.
E.g. "Joe Luser reported a bug in sendmail that causes it to generate bogus headers." "That's not a bug, that's pilot error. His "sendmail.cf" is hosed."
When the plane goes down for the usual reasons—mechanical failure, pilot error—we have collective anguish and a few questions.
Theories based on scant evidence swing from mechanical problems to pilot error and back again.
Later, a senior military officer changed the cause of the crash to pilot error.