The newest member of the Thai Airways International board, Pailin Chuchottaworn, resigned the day after he was appointed to help the airline.
The carrier, in a filing to the Stock Exchange of Thailand on Wednesday, said Mr Pailin had left the job, effective on Tuesday.
The airline provided no further details, but speculations centred on potential legal worries. The National Anti-Corruption Commission bans a cabinet minister from sitting on the board of a private company for two years after leaving the cabinet.
Mr Pailin was a deputy transport minister under Prime Minister Prayut Chan-o-cha from November 2017 to December 2019.
The THAI board appointed him to the board on Monday. His appointment was short-lived.
Prapas Kong-Ied, director-general of the State Enterprise Policy Office, said Mr Pailin had tendered his resignation to the board chairman because he did not want the rehabilitation plan to be derailed by legal issues, Post Today reported.
Mr Pailin supervised the airline when he was the deputy transport minister.
He was the president and chief executive of PTT Plc from 2011-2015.
His resignation was announced the same day the Central Bankruptcy Court accepted THAI's rehabilitation petition and set the first hearing for August.
THAI shares were up 10 satang, or 2.04%, to 5 baht on Wednesday.