Kan Air has secured approval from the Department of Civil Aviation (DCA) to resume flights from U-tapao airport in Rayong province.
The commuter airline is allowed to operate five routes out of the navy-operated airfield to Phuket, Krabi, Chiang Mai, Udon Thani and Hat Yai.
The DCA had banned the airline from operating eight routes, as the services were of a scheduled nature instead of the charter basis Kan Air had previously applied for. Effective from July 20, the new permission applies to scheduled flights.
To qualify for a charter flight permit, Kan Air would need to sell tickets on a wholesale basis and not through retail channels, the DCA said.
The ban had forced Kan Air to suspend services for five routes out of its new U-tapao hub as well as three routes from its core base at Chiang Mai airport from June 15.
Kan Air started flying from U-tapao to Chiang Mai, Ubon Ratchathani, Udon Thani, Khon Kaen and Bangkok's Don Mueang airport on April 10.
As part of the new permission, Kan Air is also allowed to open a new route, from Don Mueang to Phrae, but is not rushing to relaunch all routes any time soon.
Somphong Sooksanguan, president of Kannithi Aviation Co, operator of Kan Air, told the Bangkok Post the U-tapao-Chiang Mai route had been tentatively set for launch next month with four flights a week.
Also set by for launch next month is the Don Mueang-Phrae service, also to be served by the 66-seat ATR 72-500 turboprop.
The reduction of Kan Air's Don Mueang-Mae Sot service to two daily flights from three will free up some capacity to allow the launch of new services.
Four more routes out of U-tapao are expected this year. Critical to their launch will be additional aeroplane capacity, as its two ATR 72-500 workhorses will not be able to cope with the greater load.
Mr Somphong said the airline was looking at acquiring two single-aisle jets including the Airbus 320 to boost capacity.
The timing of launches for the four extra routes will be decided following a marketing campaign.