Airports that don't require people to undergo security checks until they move beyond the departure hall may be forced to consider a shift to screening at every entrance following Tuesday's bombings in Brussels.
With two devices apparently detonated in an open-access or "landside" area of the Belgian capital's Zaventem airport, the safety of remaining public spaces at hubs with otherwise stringent security arrangements faces renewed scrutiny.
Since the Sept. 11, 2001, U.S. attacks security provisions within the aviation industry have focused on stopping terrorists boarding planes, with measures such as full-body scans, shoe checks and bans on everything from liquids to nail clippers applied only once the passenger is past the check-in desk.
At most terminals it's therefore a comparatively easy task for a would-be attacker to walk in off the street unchallenged and mix with legitimate travelers in some of the most densely packed parts of the airport.
READ: Huge manhunt after Brussels attacks horror
"This will be a wake-up call for airlines and airports to tighten their security and introduce new procedures," said Mark Martin, a Dubai-based consultant to the airline industry. "They will have airport lock-downs and increase security in luggage, cargo, crew -- every element will be under the scanner now."
Much may depend on where governments choose to draw the line. Attacks on airports are already rare, with only one comparable incident having occurred in the past decade, when 37 people were killed by a suicide bomber in the arrivals hall of Moscow's Domodedovo hub in 2011.
The aviation industry has shown that it can adapt quickly to new threats in the past, with an immediate ban on carrying liquids through the security barrier -- later set at 100 milliliters -- imposed within months of a foiled attack on trans-Atlantic flights in 2006, changing travel habits at a stroke.
Still, while it may be possible to make airports virtually impregnable, doing so could shift the threat to other public areas, such as railway stations. There's evidence that's already happening, with November's attacks in Paris targeting restaurants, bars, a music venue and the Stade de France sports arena, yet proving just as shocking as previous outrages involving downed airliners.
Airports Council International said Tuesday in a statement that checks on people entering landside zones "could be disruptive and actually create new security vulnerabilities." Such spaces are currently no more regulated than theaters, department stores and museums, the industry body said.
Tighter restrictions could also undermine the ambitions of major airports to establish themselves as retail destinations for non-flyers. Singapore Changi, Asia's second-busiest international hub, has become a hangout for students lured by its McDonald's and Burger King outlets and local families attracted by its air-conditioned open spaces, all accessed without security checks.
U.S. airports already monitor areas before security checkpoints with artificial intelligence programs that scan for people lingering unexpectedly.
Another red flag is the wearing of excessive clothing that could disguise weaponry or explosives, said Richard Bloom, chief academic officer at the Prescott, Arizona, campus of Embry-Riddle Aeronautical University. Profiling techniques based on ethnicity or prior travel patterns have a mixed track record, and random screening may be just as effective, he said.
Stricter airport security regimes could see the wider introduction of measures that greet travelers almost at the curbside in a minority of countries.
In India, passengers must present their ticket and proof of identity on arrival and have their bags screened and sealed. The documents are still examined at the check-in counter, followed by security scans and the removal of jackets, shoes, phones, watches, belts and wallets familiar to travelers worldwide.
In disputed Kashmir and in the northeast further security checks apply before passengers board, requiring them to arrive hours before flying. People seeing off friends and family must also buy passes that aren't available at times of heightened security, while travelers can't leave the terminal once they enter.
Embry-Riddle's Bloom said that deploying metal detectors across the airport may be warranted, though many potential weapons no longer feature metal, and would-be terrorists are adept at keeping ahead of security measures.
At Paris's Charles de Gaulle and Orly airports, where controls were already at the highest level after the November attacks, extra border police began patrolling public areas, joined by riot police, according to an airport employee.
The Department of Homeland Security said it's monitoring the situation in Brussels after the attacks, which killed at least 31 at the airport and a subway station, and "will not hesitate" to introduce additional measures if needed.
Significantly upgraded security is likely to come at some expense and hurt travel times. "The long-run issue is about security costs and how that slows down flying," said Cantor Fitzgerald analyst Rob Byde. "More security checks could mean a slower turnaround of aircraft. That could be damaging."
The Washington Post
Wed Mar 23 2016
A series of apparently coordinated explosions ripped through Brussels airport and a city metro station Tuesday.
Who is Prabowo Subianto, incoming president of Indonesia?
A wealthy ex-general with ties to Indonesia's popular outgoing president and its dictatorial past, looks set to be its next leader.
Iran's supreme leader says Hamas leader's death will not halt 'Axis of Resistance'
The "Axis of Resistance", built up with years of Iranian support, includes Hamas, the Lebanese Hezbollah group, the Houthi movement in Yemen, and various Shi'ite groups in Iraq and Syria.
Putin says Russia willing to seek compromises between Iran and Israel
Russia is ready to help seek compromises between arch-foes Israel and Iran, President Vladimir Putin said on Friday, saying these would be difficult but possible.
What proposals will Russia push at the BRICS summit?
The proposal is also to establish a BRICS reinsurance company to allow uninterrupted shipment of goods and key commodities between members.
Indonesia's free meals plan in the spotlight as Prabowo readies for office
Prabowo calls the programme one of the main drivers of economic growth, eventually set to add an estimated 2.5 million jobs.
Astro AWANI's revamped English news website, AWANI International, launches on Oct 21
Astro AWANI's revamped English platform delivers in-depth global news and expert analysis to keep you informed on key developments.
Israeli strikes kill 33 people in Jabalia refugee camp in Gaza, medics say
Residents of Jabalia said Israeli tanks had reached the heart of the camp after pushing through suburbs and residential districts.
Liam Payne's ex-partner calls for media restraint after 'painful' death
Cheryl Tweedy used her statement to urge the media to remember they had a seven-year-old son, Bear, who could read the reports.
Analysts: Indonesia's strong MoF leadership team to boost investor confidence
Sri Mulyani Indrawati as head of Indonesia's Ministry of Finance is expected to instil confidence among investors.
Biden offers both a carrot and a stick to Israel as his term nears an end
Israel has frequently resisted US advice and has caused political difficulties for the Biden administration.
Putin says BRICS will generate most of global economic growth
Russian President Vladimir Putin will host a summit of the group in the city of Kazan on Oct. 22-24.
ISIS Malaysia's perspective of Budget 2025
An excellent rakyat-centric budget under the overarching principle of a caring and humane economy.
Budget 2025: Record increase in STR, SARA aid initiatives
The government will provide a significant boost to the Sumbangan Tunai Rahmah (STR) and Sumbangan Asas Rahmah (SARA) initiatives next year.
Budget 2025: EPF contributions to be made mandatory for foreign workers – PM Anwar
The government plans to make it compulsory for all non-citizen workers to contribute to the Employees Provident Fund (EPF).
What policies to expect from Indonesia's new President Prabowo
Prabowo will be open to foreign investment, his aide has said, such as by offering investors management of airports and sea ports.
Budget 2025: Govt allocates RM470 mil to empower women's participation in PMKS
The Women's Leadership Apprenticeship Program will be intensified as an effort to produce more female corporate personalities.
Israel sends more troops into north Gaza, deepens raid
Residents of Jabalia in northern Gaza said Israeli tanks had reached the heart of the camp, using heavy air and ground fire.
Indonesia ramps up security ahead of Prabowo's inauguration
Prabowo Subianto will be sworn in as Indonesia's president on Sunday with Vice President-elect, Gibran Rakabuming Raka, also taking office.
Immediate allocation of RM150 mil for local authorities, DID to tackle flash floods
Datuk Seri Anwar Ibrahim said this allocation is intended to address the recent flash floods that hit the capital and several major towns.
Budget 2025: Sabah, Sarawak to continue receiving among highest allocations - PM
Sabah and Sarawak continues to be prioritised under Budget 2025, with allocations of RM6.7 billion and RM5.9 billion respectively.