The captain was still alive when he arrived at Saint Alphonsus Regional Medical Center but died overnight while undergoing treatment, spokeswoman Jennifer Krajnik said Friday. A Boise airport spokeswoman said Thursday that the man suffered an apparent heart attack. The cause of death has not been announced.
The news lit up social media in the early morning hours Friday, with dozens of tweets sent out about the pilot's death.
Passenger Ken Martin told Seattle TV station KOMO (http://bit.ly/19Fu3A4) a first-year resident doctor sitting next to him volunteered to help perform CPR. She told Martin the pilot appeared to weigh over 300 pounds and was taken into the first class cabin where CPR was performed.
Passenger Bryant Magill described a calm scene onboard.
"I'm really impressed with all the flight attendants," Magill told KOMO. "They kept themselves calm. They kept it professional. There was no panic on the plane."
The airline did not give the pilot's name, citing privacy reasons.
"I am sad to confirm that our co-worker passed away last night. Our thoughts are with his family at this time," spokeswoman Christen David said in an email.
Another off-duty United pilot was onboard and helped land the plane, David said.
Pilots are required to get medical certificates that show they don't have major heart problems, according to the Federal Aviation Administration website.
United flight 1603 from Houston to Seattle diverted to Boise for the medical emergency. The flight landed safely about 8 p.m. local time and was met by paramedics who took the pilot to the hospital. The Boeing 737-900 had 161 passengers and a crew of six on board.
David says another pilot flew the original plane and passengers to Sea-Tac Airport.