'This Is the Captain. I'm the One That's Ill'

It's unusual but far from unheard of for commercial flights to divert due to medical emergencies. It's much rarer for the person having the medical emergency to be the one in charge of the cockpit, as happened with Delta Airlines Flight 437 on Tuesday. The Los Angeles-to-Boston flight made an emergency diversion to Detroit and landed safely under the control of the first officer, the New York Times reports. "This is the captain," the pilot told air traffic controllers. "I'm the one that's ill. I'm going to taxi the jet to the gate, and then I need to go to the hospital."

Delta says the Boeing 757 landed without incident, with the first officer handling the controls while the captain managed radio communications, a setup aviation experts describe as routine backup. After a brief mix-up over gate assignment, the jet parked and another crew took it on to Boston. The 147 passengers arrived at their destination just 90 minutes behind schedule.

Former military and commercial pilot Matthew "Whiz" Buckley tells CBS News that the pilots "did this by the book." "In airliners, if you're not flying, you're the one doing the talking, because that allows, in this case, the first officer, to focus on just flying the airplane. So, yeah, that makes perfect sense as to why he's communicating," Buckley says. "If any pilot is incapacitated or feeling incapacitated, like, 'Hey man, this is pretty bad,' you need to divert to the nearest suitable airfield." The airline hasn't disclosed the nature of the medical emergency, but there have been suggestions it was appendicitis, per SimpleFlying.