6. Beloved, goofy Colonel Blake ran the 4077 until the end of season 3. What happened to him?
From Quiz The Whys Behind the Goodbyes
Answer:
Discharged and shot down over the sea of Japan
The world of American television in 1975 was much different than today. With just three major networks on TV, Americans generally watched the same shows and became very attached to the characters and storylines. That's why Red Shirts were killed off on "Star Trek", not Captain Kirk, Mr. Spock, etc. So the last few minutes of Henry's last episode were shocking to everyone, including most of the cast.
If you are a true "M*A*S*H*" fan, you probably know these words by heart:
"I have a message. Lieutenant Colonel... Henry Blake's plane... was shot down... over the Sea of Japan. It spun in... there were no survivors." -- Corporal Radar O'Reilly
According to Biography Channel's "The Truth Behind the Sitcom Scandals", McLean Stevenson had been unhappy that Alan Alda's character of Hawkeye seemed to be becoming the show's star, instead of it remaining more of an ensemble. He complained frequently, and, because of the bad blood, the producers of the show killed off his character so he couldn't return.