American Airlines (AA, Dallas/Fort Worth) has informed the US Federal Aviation Administration (FAA) of a recent incident in which it allegedly used a non ETOPS-certified A321-200 to operate a flight from Los Angeles International to Honolulu, Hawaii last month.

Los Angeles-based aviation journalist Brian Sumers says the oversight occurred on August 31 - just twelve days after the A321's route debut on August 18 - while flight AA31 was out over the Pacific.

An employee reportedly discovered that the aircraft in use on the flight - N137AA (cn 6647) - was not ETOPS certified and informed management who subsequently informed the FAA of the error. While the aircraft continued for a safe landing in Hawaii, its return sector was cancelled with departing passengers ferried back to the US mainland on another jet.

The FAA is now investigating the incident.

Of American's 165 A321-200s, only a handful are certified for Hawaiian operations and have thus been designated A321Hs. While the aircraft have the range to reach the Hawaiian islands, the A321H fleet is fitted with auxiliary fuel tanks to allow for diversion to an alternate airfield within 3 hours flying time.