When Qantas flight 1 touched down at Don Muang airport on September 23, 1999, visibility was low, the rain was heavy, and the 747 jumbo jet was well down the soggy runway. The plane came to a stop 220 metres onto the adjoining golf course, landing gear crushed, engines damaged and the passengers dazed and in the dark.

While the official evaluation noted human factors contributed to the accident, it also pointed out that the runway surface lacked grooves to help shed the rainwater and increase the efficiency of the plane's tyres to stop on wet surfaces.

These grooves, generally two to three centimetres deep and spaced three to four centimetres apart, have for years been placed across runway surfaces to help increase safety margins in wet conditions. It was therefore no surprise that grooves were part of the runway specifications for the new Suvarnabhumi Airport.

However, when the airport begins operations next Saturday, only one of the two runways will contain such grooves.

"It's true we designed the airport to meet international standards with grooved runways," says Somchai Sawasdeepon, general manager of Suvarnabhumi Airport. "But we completed the first [western] runway and put loads on it for testing, and it became apparent that the grooved asphalt broke into pieces. These could become what we call foreign object damage [FOD] and we have to keep sweeping the runway to make sure they don't damage the planes."

As a result, plans were abandoned to put grooves in the eastern runway, which Somchai states saved the airport more than Bt10 million. He also confirmed the airport would not use grooves in the two runways planned for future expansion.

"We had second thoughts about grooving, feeling the practice was originally designed for airports in the West where snow on the runway is a problem. We don't have snow in Bangkok," he stated.

Such a revelation came as complete surprise to Captain Nokdee, a long time pilot who asked for his real name to be withheld. He finds such grooves to be very helpful, which is why he believes they are commonplace at major airports all over the world, including the newest ones in Hong Kong and Kuala Lumpur.

"Grooves make landings safer. We classify aircraft braking ability into poor, medium or good. Although grooving won't increase braking effectiveness from say poor to medium right away, it certainly brings it up a few steps," the captain explained.

He says pilots employ a numbering system to rate runway friction, with three or below being poor and nine being good. Grooving can increase the number by a few points, which he says is especially important in heavy rain.

Although runway safety issues often focus on the landings, grooving is also critical for take-offs, said the captain, as engines sometimes have problems and the pilot must abort and brake quickly.

Tortrakul Yomnak, former president of the Engineering Association of Thailand, says this change of plans at Suvarnabhumi should not surprise those following developments there.

"The low quality asphalt used made the grooves break apart." Tortrakul explains. "Instead of requiring contractors to change the asphalt, the AoT simply told the contractors not to groove the other runway."

Bids on Suvarnabhumi construction projects were quite competitive and Tortrakul feels corners may have been cut to preserve profits. "We know those winning companies got the projects with very low bids. They will not make much money out of these contracts."

However, Captain Permsak Thongpaiboon, president of the Pilots' Association of Thailand, saw little cause for concern. He says there are new asphalt technologies that can help shed water.

"I don't think we have to worry about the quality of the runways. If they are not up to standard, ICAO won't allow the airport to operate," he said.

Neither Captain Nokdee, nor Tortrakul were aware of such technologies. A quality control engineer at Suvarnabhumi could not confirm there was anything special about Suvarnabhumi's asphalt, but did claim tests were done to ensure the friction on the two runways was comparable.

As The Nation has been reporting this week, ICAO will not be certifying any aspect of Suvarnabhumi's operations. Additionally, ICAO guidelines actually do not require runway grooves.

"It's true runway grooving is not a compulsory safety requirement by ICAO, but leading airports all over the world have their runways grooved," Tortrakul said.

"In this day and age it is not enough to just say we didn't do anything against the written rules. Suvarnabhumi is a brand new airport, why don't we start by doing things right and live up to international standards."

Nantiya Tangwisutijit

The Nation