A woman lights a candle for the victims of the Metrojet crash at a memorial in St Petersburg
Confirmation from Russia that the Metrojet aircraft which crashed in the Sinai desert was indeed brought down by a bomb, combined with the febrile atmosphere generated by the tragedies in Paris, are likely to focus renewed attention on aviation security - and particularly in airports.
Some security experts say what is needed is more intelligence-based, risk-based screenings of both passengers - and airport staff.
For decades, it has been well known that aircraft are prime targets for terrorist attacks. A relatively small explosion is capable of bringing down a large aircraft, inflicting numerous casualties.
Even before the cause of the Metrojet crash was known for certain, leading figures within the industry were warning that changes would be needed.
The chief executive of Easyjet, Carolyn McCall, recently told the BBC that the idea of a bomb on board an aircraft "kept airline chief executives awake at night". She added that in "certain airports" around the world, standards simply weren't good enough.
Her comments echoed a warning from the UK's Foreign Secretary, Philip Hammond, who said that travellers could face delays and extra costs as a result.
What can be done?
Global standards for airport security do already exist. They are laid down in Annex 17 of the Chicago Convention, a document that effectively sets out international rules for the air transport industry. It states, for example, that both passengers and baggage should be screened before being allowed aboard an aircraft.
A French soldier patrols Paris's Charles de Gaulle Airport
However, these are only minimum requirements. It is up to individual governments to decide how to implement them, and of course the airport itself has to abide by those national procedures.
In practice, this means that standards can vary widely. Security in major hubs such as London Heathrow is generally very good, with state of the art technology being used by well-trained staff. But in regional airports, particularly in the developing world, standards can be more lax.
Organisations such as the US Transportation Security Administration have overseas representatives whose job is to help foreign governments boost security, but experts say the results have been mixed.
In any case, standards can slip almost anywhere. The TSA itself came in for heavy criticism earlier this year, when government agents managed to smuggle fake weapons and explosives through security at US airports in 67 out of 70 attempts.
More physical checks?
So what can be done to improve matters? Physical checks on passengers were dramatically tightened up after the 9/11 attacks, and the subsequent attempt to bring down another aircraft by the "shoe bomber" Richard Reid.
Further measures were introduced after the unsuccessful liquid bomb plot of 2006. Even today, it's not uncommon to be asked to remove shoes when passing through security, while curbs on carrying liquids have been eased somewhat, but remain in force.
Not every passenger poses the same amount of risk, says Matthew Finn
According to Ben Vogel, editor of Jane's Airport Review, there is no need for further restrictions of this sort.
"If tighter screening controls are introduced," he says, "it would run counter to aviation policies over recent years."
"The talk in recent times has been about intelligence-based, risk-based screening. Risk-based protocols rely less on a blanket one-size-fits-all method, and use a more nuanced approach that focuses on 'persons of interest'."
Matthew Finn, managing director of security consultancy Augmentiq, agrees. "We cannot continue to view every passenger as posing the same amount of risk," he says.
"The 85-year-old grandmother and the 3-year-old toddler do not pose the same amount of risk as someone who might already be known to the authorities, travelling on a one-way ticket to a destination that gives us cause for concern."
Such an approach might actually be welcomed by passengers. Current security procedures can be very time consuming, while some people find them embarrassing and undignified.
But those in favour of greater risk profiling say it would allow most people to undergo less intense screening, potentially reducing delays and stress at the airport.
Airside clampdown
However, many experts believe the priority now should be to focus, not on passengers, but on the people who actually work within the airport.
Security procedures need to focus on airport staff, as well as passengers, say security experts
Security staff, for example, are often low paid and poorly trained. In countries where corruption is endemic, there is a risk they could be paid to turn a blind eye to potentially suspect baggage.
Low morale, meanwhile, can mean experienced staff leave the industry, depriving it of much-needed expertise.
"The technology, manpower and procedures at airports are only effective if they are deployed correctly", says Matthew Finn.
"We've got to move away from low wages, tenuous contracts and minimal opportunities to create a culture that recognises high performers."
But security staff are not the only airport workers under scrutiny.
Anyone who works "airside", beyond the security screen is potentially a risk. That includes people like baggage handlers, bus drivers, maintenance staff and engineers.
"It only takes one person, one 'bad egg' to cause a disaster," Philip Baum, editor of Aviation Security International, told the BBC.
Passengers queuing for security checks at Amsterdam's Schiphol airport earlier this year
"We've seen a multitude of incidents around the world where airport employees have been engaged in human trafficking, drug trafficking
"But… it could easily be an improvised explosive device that's infiltrated, for example."
Mathew Finn of Augmentiq thinks that, like passengers, airport staff should be subjected to more risk-based screening.
"We've spent incredible amounts of money focusing on what passengers may have in their bags, but nowhere near enough on who is being screened at security or who is working in restricted areas of the airport," he says.
One thing the airports themselves do not want to see is increased regulation. According to Angela Gittens, director of the industry group ACI World, that would be "counterproductive".
However, it is fair to say the loss of flight Metrojet KGL9268 has put the security of airports under an intense spotlight - and the "inside threat" posed by airside workers is being taken more seriously than ever.
