The three are Thai Airways International, Bangkok Airways and Thai AirAsia.
Civil Aviation Authority of Thailand director Chula Sukmanop said he believed the AOCs will be reissued to the three airlines by January or February.
After passing the process involved in examining aviation documents at the end of this month, the airlines will go through the next stage which is aircraft inspection.
The entire process will take about five months, he said.
Mr Chula said the agency initially aimed at re-issuing AOCs to eight airlines by February. However, the new AOC inspections for the five remaining airlines will begin in March.
He said the new timetable was for all 25 remaining airlines to pass the re-inspection with AOCs issued by September next year.
The ICAO inspectors will also be invited to conduct fresh inspections to save time in a bid to lift the red flag as quickly as possible.
Mr Chula, however, said the agency was facing a lack of qualified staff to issue AOCs, which was among the safety concerns raised earlier by the ICAO.
In order to solve the problem, existing inspectors have to be rotated so it will not affect the re-issuing of AOCs.
As for solutions to the significant safety concerns, Mr Chula said Transport Minister Arkhom Termpittayapaisith ordered the relevant agencies to report directly to the ICAO through its website by the end of the month.
If the ICAO reviews the report and finds any flaws, it will inform Thai authorities. But if there are no mistakes, the certificates will be approved.
Read original story here.