A plane not certified to travel for long distances over water was used to fly from Los Angeles to Hawaii last month, American Airlines has confirmed.
Passengers arrived safely to their destination after the 31 August incident, in which an A321S plane was used instead of a A321H.
The A321S has less safety and medical equipment on board than the A321H.
American Airlines is investigating the plane mix-up with the Federal Aviation Administration.
“Whether the plane was going to make it there was never a question,” company spokesman Casey Norton told the BBC.
Mr Norton said the two planes are equipped with the same engine, fuel tanks, range and basic safety features.
The A321H plane, because it is used for long flights, comes with more medical supplies and safety features like fire suppression.
