In its report on last year's crash of a Lion Air MD-82 at Adi Sumarmo International Airport in Surakarta, Central Java, the National Transportation Safety Board (NTSB) said that the accident was due to water accumulating on the runway following heavy rain, which led to the plane skidding off the tarmac.
"After conducting an investigation, we concluded that the plane experienced hydroplaning, a condition where the amount of water on the runway makes it slippery like ice," said NTSB investigator-in-charge Ertata Lananggalih.
Flying from Jakarta, the Lion Air McDonnel-Douglas MD-82 plane skidded off the slippery runway after landing at the airport on Nov. 30, 2004. It then crashed into a concrete structure that tore the front part of the aircraft's body open before it came to a halt after slamming into the metal fence of a nearby cemetery. A total of 26 people died in the accident and 56 others were injured.
Ertata said that there were more than three millimeters of water on the runway at the time the plane landed.
He explained that the accumulation of such excessive water could have been caused by the blockage of a drainage channel. However, an audit of Adi Sumarmo airport failed to reveal any drainage problems.
Besides the slippery runway, the accident was also contributed to by a strong tailwind and the fact that the plane's spoiler and reverser had jammed a few seconds after landing.
The spoiler and reverser are components that help slow down a plane after landing. The malfunctioning of these two parts hampered the deceleration of the plane.
A strong tailwind of 13 knots prolonged the skid.
"One knot of tailwind requires 60 more meters of runway," said Ertata. The length of the runway at Adi Sumarmo International Airport is 2500 meters.
The Lion Air accident prompting the transportation ministry to audit 23 international airports in the country.
Seventeen of the audited airports -- including Adi Sumarmo International Airport -- had problems related to runway rubber deposits on their touchdown areas, while 12 of the 23 airports did not have the additional 500 meters of runway required as an additional safety measure.
The ministry has issued binding recommendations for the upgrading of these airports.
Other problems affecting airport runways were water accumulation, large and small cracks, and faded runway markings.
The only airport given a completely clean bill of health was Pattimura International Airport in Maluku.
Meanwhile, the ministry's Director of Air Transportation Cucuk Suryo Suprodjo said that during a previous audit conducted before last year's Idul Fitri holiday, Soekarno-Hatta International Airport in Cengkareng, west of Jakarta, was also found to be free of any major problems.
The accident prompted the ministry to conduct a safety audit on 11 airlines, including airline management, company procedures, aircraft maintenance, cabin crew licenses and operational procedures.
The results revealed that most of the airlines followed the regulations but each had certain specific areas of concern that needed follow-up. (003)
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