Delta sent the replacement plane to Cold Bay after a Boeing 767 landed there safely at 6 a.m. Wednesday with 167 passengers and 11 crew members on board.
Delta spokesman Michael Thomas says Flight 208 was diverted as a precaution after an engine warning message flashed.
No injuries were reported aboard the plane that departed from Tokyo.
State transportation spokeswoman Jill Reese says the replacement plane departed from Cold Bay shortly before 4 p.m.
Cold Bay was built up as a World War II staging area. The state maintains the 10,000-foot (3,000-meter) runway at the site 625 miles (1,000 kilometers) southwest of Anchorage.