Changi Airport has stepped up security checks since the disappearance of Malaysia Airlines Flight MH370 more than two weeks ago.
The heightened security is a "precautionary measure", the Singapore Police Force and Immigration and Checkpoints Authority of Singapore (ICA) said yesterday.
Airport Police commander Sam Tee, who briefed reporters on the security procedures at Changi Airport, said that measures have been reviewed in the wake of MH370's disappearance.
On March 8, the Malaysia Airlines flight vanished en route from Kuala Lumpur to Beijing.
The twin-aisle Boeing 777-200ER plane has yet to be found, but the authorities have confirmed that at least two Iranian passengers boarded the jet with stolen passports.
At Changi, the police have "enhanced some of the checks" and there is also a "stronger ground presence", Mr Tee said. For example, travellers' identities now come under closer scrutiny, he added, without elaborating.
Singapore is one of the few countries that check visitor passports against Interpol's database of lost or stolen travel documents.
If a passport is found to be one of more than 40 million on the global police agency's list, the immigration officer at the counter is automatically alerted and the traveller pulled aside for further checks.
The Straits Times understands that in the last two weeks, selected flights - based on risk assessment - have been subjected to tighter screening. This includes more thorough checks like pat downs for departing passengers.
Several airlines also said that a briefing was held recently to remind everyone to stay vigilant.
On top of the stepped-up measures, the Airport Police conducts daily security checks and monitors the premises using cameras that are installed airport-wide.
The airport's facade has been strengthened in recent years to protect the terminals from outside explosions.
At Changi, all departing bags originating in Singapore and bags transferred from one aircraft to another are put through a five-level screening system.
Mr Paul Yap, who was the head of aviation security at Changi Airport before leaving in 2006 to lead Temasek Polytechnic's aviation department, said risk management is key.
"At the end of the day, there is a cost to everything. You can have all the checks but you also need to look at the impact on Changi's efficiency, for example," he said.
To balance between passenger convenience and the need to ensure security, the Airport Police adopts a "whole-of-government" approach and works closely with relevant agencies, including Changi Airport Group and the Civil Aviation Authority of Singapore, Mr Tee said. "Over-security or under-security is equally sinful and we should not go to the end of each spectrum," he said.
"Risk management is about making sure we have good information on what has happened, we have good intelligence and an understanding of some of the facilitation issues that we will face, and then we work together as a team," Mr Tee added.
The ultimate objective is to secure the airport "without causing severe inconvenience or disruptions to airport operations", he said.
With more stringent checks in the wake of MH370's disappearance, Mr Tee said: "The police and ICA are monitoring the security thrust situation closely. We appreciate the understanding and patience from travellers as we conduct the various security checks to ensure safe and secure travel."
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