The agency will release the result of its investigation into Thailand's aviation safety standards on June 18.
Prajin expected three scenarios. The ICAO may approve Thailand's plans to revamp the standards, reject the plans or extend the investivation.
The ministry mulls a press conference on Thursday, after the ICAO's release.
Thailand submitted the overhaul plan to ICAO in April, two months after ICAO expressed serious concerns on Thailand's safety standards which involve five airlines registered in Thailand.