Thai AirAsia has issued an apology after 23 passengers were left aboard a shuttle bus at Don Mueang airport and nearly abandoned as their flight prepared for departure, until a woman raised the alarm about her missing friend.

The Civil Aviation Authority of Thailand (CAAT) has ordered the carrier to explain the incident and take steps to correct the problems it identified.

It happened on a flight from Don Mueang to Hat Yai on Jan 17, scheduled to depart at 7.10am with 136 passengers on board. The CAAT said it received a formal passenger complaint on Jan 29.

According to a passenger account shared on social media, the drama began when an elderly passenger could not see her friend, who had checked in and boarded the bus, on the aircraft.

As the plane began taxiing, she unbuckled her seatbelt and alerted the cabin crew that her friend was missing. She insisted the aircraft could not depart as her friend had checked in and was on the shuttle bus.

Initially, cabin crew said the missing passenger had missed the flight and could catch the next one, or had possibly boarded the wrong bus.

However, the woman’s phone call confirmed not only her friend but 22 other passengers remained trapped on the bus with its doors closed, forcing crew to acknowledge the serious oversight.

The aircraft returned to its parking position at approximately 7.45am, where the 23 stranded passengers finally left the bus and boarded the plane.