Sure, pilots could have used SOS, but the consonants could have easily been mistaken for some other similarly sounding ...
The deadliest crash, United flight 232, happened when a Douglas DC-10 flying from Denver to Philadephia experienced an engine failure and made an emergency landing in Sioux City on July 19 ...
From United Flight 232 in Sioux City to the loss of Buddy Holly in Clear Lake: What's Iowa's history with fatal plane crashes ...