Dozens of Alaska Airlines flights were canceled or delayed Monday after the carrier requested a ground stop during an IT outage Sunday night.

On November 24, 1971, a nondescript man calling himself Dan Cooper approached the counter of Northwest Orient Airlines in Portland, Oregon and pulled off a daring mid-air hijack.

When Northwest Orient Flight 2501 crashed, it was the worst aviation disaster in U.S. history.

Northwest Orient Airlines Flight 2501, at the time the deadliest commercial airlines disaster in American history, disappeared when it flew into a storm over Lake Michigan on June 24, 1950.