A Korean Air executive is under investigation over claims she delayed a plane over the way she was served nuts.
Heather Cho demanded the removal of a crew member from a flight last Friday for failing to serve nuts on a plate.
Ms Cho, a vice-president of the firm, forced the Incheon-bound flight to taxi back to the terminal in New York.
The airline said checking service standards was part of her job, and she had the pilot's backing. But officials said she was a passenger at the time.
Local media reports said that a junior attendant had offered Ms Cho macadamia nuts in a bag, instead of serving the nuts on a plate.
Ms Cho, daughter of company boss Cho Yang-ho, then questioned the chief flight attendant over in-flight service standards and ordered him off the plane.
Korean Air said the plane arrived 11 minutes late, and that the decision to expel the senior flight attendant had been made in consultation with the pilot.
The airline told Korea Times that checking of quality of service was one of Ms Cho's jobs, as she is in charge of in-flight service for the carrier.
The transport authorities are investigating whether Ms Cho's actions infringed aviation law.
"Even though she is senior vice president at the company, she was a passenger at that time, so she had to behave and be treated as a passenger," a South Korea transport ministry official told reporters.