white knuckler
n. A bumpy or problem-plagued airline flight; a nervous passenger on such a flight.
Other Forms
Commuter aircraft are far safer and popular than they used to be, but they are five times more likely than larger airliners to have a fatal accident, according to government statistics.

The small planes, known to travelers as "puddle jumpers" and "white knucklers," are the fastest-growing part of the nation's airline industry.
—Philip Brasher, “Commuter Planes Safer, But Not Up To Large Airliner Standards,” The Associated Press, December 04, 1993
Woodrum Field airport in Roanoke was closed temporarily after a 19-seat Air Virginia plane bound for Philadelphia slid 10 feet off a runway into a grassy area, startling the six passengers and two crew members.

"It was a white knuckler," said passenger Robert Hummel, director of marketing development at ANR Coal Co. of Roanoke.
—Linda Wolohan, “Winter Storms Push Snow, Ice From Idaho To The Midlands,” Sarasota Herald-Tribune, December 23, 1981
1969 (earliest)
George Seaton, who confesses to having once been "a white-knuckle air passenger," has taken charge as pilot of the biggest flight movie in recent Hollywood years, "Airport."
—Bob Thomas, “'Airport' Director Former White Knuckler,” Tuscon Daily Citizen, January 22, 1969
This phrase is also commonly used to refer to anything that causes anxiety or stress, particularly when we have to hold something during the experience (such as an armrest, a roller coaster handrail, or the grip of a golf putter). The tight grip forces blood away from the knuckles, turning them white.