THE ever-growing number of air travellers, along with outdated equipment, is taking its toll on Jakarta's Soekarno-Hatta International Airport, leading to technical glitches that occur with increasing and worrying frequency, as well as packed terminals.

Following incidents of non-operating phone lines and a string of blackouts, the airport's radar shut down for at least 30 minutes at 9am on Sunday.

Suddenly, the city's notorious traffic snarls were no longer just on the streets but also up in the air, with nine aircraft forced to hold for 20 minutes. On the runways, 15 aircraft had to queue for take-off.

National Transportation Safety Commission chairman Tatang Kurniadi said the airport operator was playing a dangerous game with its reluctance to maintain and update equipment. "There should be no excuse for technical failures because it has standard procedures to prevent these sorts of incidents from affecting service and safety," he said.

Mr Haryanto, executive manager of airport operator PT Angkasa Pura II, said the airport authorities were still looking into what caused the failure. "It was out of our control. We are still investigating the case," he said.

He admitted this was not the first incident of the radar failing, as a similar incident had occurred in June last year.

Opened in 1985, the Soekarno-Hatta airport replaced Kemayoran airport in Central Jakarta and Halim Perdanakusuma airport in East Jakarta. The airport was designed to cater to 22 million passengers a year. Mr Haryanto said the number of air travellers last year was 37.3 million. In the first half of this year alone, the airport recorded 20.7 million passengers.

"(The technical problems) are signs that we have to speed up this airport's expansion," Mr Haryanto said. He gave assurances that there were no funding issues as the company had raked in fat profits in the recent past.

However, aviation-industry observer Alvin Lie blamed the problems on the company's refusal to invest in expanding both technology and physical capacity. He said this violated a regulation issued by the International Civil Aviation Organization that stipulates that all revenues from an airport's air-traffic services be fully invested in expansion.

"The expansions are necessary not only to improve services, but also to ensure safety," Mr Lie said, adding that outdated equipment, including radar systems, endangered public safety.

The country's aviation industry had been marred by frequent air accidents, leading to a blanket ban on all Indonesian-flagged aircraft in the lucrative European market. The ban was lifted earlier this year.

Aviation expert Dudi Sudibyo said that to keep pace with the growing number of travellers, the airport's capacity should be expanded to serve up to 50 million passengers.

"If such an expansion is not possible, (the operator) might also consider using Halim (airport) to cater to domestic flights," he said.