The jetliner, an Airbus A340-600, made an emergency landing at Seattle-Tacoma International Airport when an irritating smell started making some passengers sick.
Flight 459, operated by Lufthansa, was carrying 323 passengers to Munich, Germany when some passengers reported an irritating odor, described as an "electrical smell."
Before midnight the flight landed at Sea-Tac Airport. Seattle medics checked out a passenger and three crew members who were sickened by the odor. All are expected to be OK and no one was taken to the hospital.
Passengers had mixed reaction to the emergency landing.
"Pretty calm, very relaxed," said one passenger.
"Very annoying, but what are you going to do when they ground the plane and claim safety?" said another.
There is no word yet on what caused the strange smell.
All passengers and crew members were put up in local hotels overnight and are expected to resume their flight on Friday.