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After the twin attacks in Belgium, the Brussels suburbs of Zaventem??? and Maelbeek??? will be inextricably linked to the horrendous loss of more than 30 lives at the hands of terrorists.
As a former aviation journalist based in Brussels, I also associated the name Zaventem with the headquarters of the North Atlantic Treaty Organisation, which is just down the road from Brussels Airport. 
Inevitably, questions will be raised about the adequacy of security at Brussels Airport. Beyond this, there will be debate around at what point people entering an airport should be security screened. It will affect every major terminal around the world, including those in Sydney.
Today, international airports divide their departure areas into the "air side" for everything beyond the security checkpoint and the "land side" for everything before. The trade-off for lining up through scanners and removing your belt and shoes is tax-free shopping. But those being waved off by family and friends might wish to linger longer land side before venturing into the sealed confines of air side.
There is a desire from those who run airports to maximise the real estate in terminals by shifting the line between air side and land side line closer to the gate, allowing more passengers and non-travellers to mingle in common areas.
Airports such as Singapore Changi are seen as destinations in their own right by locals, who are drawn to the wealth of shops and attractions in the terminals. Elsewhere, luxury car forecourts and IKEA showrooms have all featured in airport terminals.
Technology is making this halfway line appear more arbitrary. Remote check-in is already the norm for domestic flights and mobile phone check-in for international flights is growing. In the US, for example, passengers can scan the machine-readable page of their passport on their phone at check-in to trigger pre-flight clearance checks.
The next step is number-plate recognition check-in for frequent flyers. Drive up to an airport in a car that is registered and your name will be added to the airline manifest.
Add to this remote bag checks, where passengers will be able to deposit luggage at locations in city centres and the need for a check-in hall becomes moot. Downtown bag drops, abandoned in the early 2000s due to the threat of rogue baggage handlers, are back on the agenda, thanks to robotics. Fully automated baggage services offer a more secure alternative to in-airport baggage-drop areas.
Yet, as the attacks in Brussels sadly show, it is the non-secure areas of airports that pose the challenge for security. Wherever passengers mingle with non-travellers, there is the danger of another attack.
The topic of terminal security will be debated when Asia's airport chiefs descend on Australia in   April for the Airports Council International Asia-Pacific regional assembly on the Gold Coast. The answer the delegates probably do not want to hear is that a move towards making entire terminals security screened is now more likely than embracing a retail-led Changi model.
Every new terrorist attack at an airport has implications for air travellers. Body scanners were introduced in the wake of the foiled 2009 plot by Umar Farouk Abdulmutallab??? to bomb a flight to Detroit using liquid explosives in his underwear.
In the likely shake-up of air-side land-side demarcation that will follow the Zaventem attacks, the impact will be felt by all. Meeters and greeters would have to clear security to get inside to wave off their loved ones.
This will undoubtedly induce short-term pain, as the hassle of parking and screening will be new to non-passengers. Experience shows us, however, that people get used to the inconvenience and regard it as a price worth paying for their security. The challenge for Australian airports will be to manage the transition.
In time, the leisure nirvanas envisaged by airport operators might still come to pass. The model relies on having a mix of travelling and non-travelling customers. Retail planners at airports here will have to assume a future scenario where everyone in a terminal has been screened. This will have huge flow-on benefits for travellers once inside, but will require legislative change on border controls and duty-free sales.
Of course, twice the number of people killed at the airport lost their lives on a packed metro train. After similar attacks at Madrid's Atocha??? station in   March 2004, security screening was extended to Spain's Ave high-speed train network. Time will tell what safeguards can be put in place to protect ordinary commuters on public transport.
Justin Wastnage is the principal of Message Shapers Public Affairs, an aviation and tourism policy consultancy, and is on the board of the Aerospace-Aviation Australia Association.