The plane crashed into nearby swampland and burst into flames, but forty-five people on board survived.
Surat Thani airport's Instrument Landing System (ILS) had been removed during construction work to extend its runway, said an air traffic control official at the airport who did not want to be identified by name.
A Thai air force pilot who had just flown into the airport Sunday said that the removal of the system meant pilots had to use a less accurate radio navigation system that relies on a visual sighting of the runway once the aircraft has descended to 500 feet (152 meters).
``The only system working at the airport is the radio system,'' he said. ``In bad weather all pilots prefer the ILS system over the radio system,'' he said.
Survivors of the crash said the pilot had complained of poor visibility, had twice failed to land and was trying a third time when the aircraft crashed into flooded swampland about three km (two miles) from the airport.
There were 45 survivors, including 12 of the 25 foreigners on board.
The pilot said the radio system guided the aircraft in a diagonal rather than straight approach to the runway and a visual sighting of the landing strip was needed to adjust the flight path for a straight landing.
``If you don't see the runway you should miss the approach and go around,'' he said.
All pilots, both civil and military, had been informed that the ILS was not operating at Surat Thani and that they needed to rely on the radio system and runway landing lights, the air force pilot said.
``If you cannot see the runway on the third attempt, then it's better to divert to another airport which has the ILS system,'' he said. The southern Thai airports at Hat Yai and Phuket had ILS.
The other alternative for the plane that crashed would have been to return to Bangkok, he said.
The Thai Airways pilot told passengers before the crash that if he could not land on his third attempt he would turn the plane around and return to the Thai capital.
Officials at the airport and at Thai Airways have declined to provide details of the navigation system except to say that a radio navigation system was functioning normally.
Asked Sunday if navigation systems at Surat Thani were up to international standards, the president of Thai Airways Thamnoon Wangle told reporters: ``I do believe so.''
The 700 million baht ($19.5 million) runway extension project at Surat Thani began in August last year and should have been competed in July this year, but work was delayed by Thailand's economic crisis, airport staff said.
The air traffic controller said pilots all over the world had been notified several months ago that navigation facilities were inadequate at Surat Thani for low-visibility landings due to the work on the runway and so they should not risk more than two approaches.
He said antennae for the ILS navigation system had to be installed at the head of the runway and that could not be done until the work on the strip was completed.
``All of the pilots knew. They should not have attempted a third approach,'' the controller said.
Investigators from the National Investigation Team for Air Accidents had already interviewed staff on duty at the Surat Thani airport's air control tower on the fateful night of the crash, the airport's director general, Chamnong Sarnhaksorn, told reporters.
He added that all the air traffic control equipment at the airport on the night of the crash had been fully functional.