Otso Iho, deputy head of Jane’s Terrorism and Insurgency Centre, IHS Markit, said there were about 100 drone-related incidents in the UK last year with 40 being classed as serious, during a panel discussion at Routes Europe 2018 in Bilbao on threats to the continent’s aviation market.

With these incidents occurring at anywhere between 400m and 4,000m, Iho argued it was becoming increasingly likely that a terrorist group like Isis would use one in Europe, particularly after they started employing the technology in Syria.

Iho said: “That’s a new technology that we warned about and someone using it in a negative way.”

He added the situation has also worsened following the effective defeat of Isis in Syria and Iraq, which led to many fully trained foreign fighters now returning to their homes in Europe and still nursing grievances.

Meanwhile, Brussels airport’s head of aviation marketing Leon Verhallen said following the attack on his airport in March 2016, the most important thing to do was to keep everyone - from airline partners to the paying public - fully informed of the situation.

However, he added that even with a full police investigation into the attack, finding out the information proved to be difficult.

Verhallen said: “The airport loses control and contingency planning goes to the local government rather than the airport.

“[People said] ’can you open the airport’ and you cannot. We didn’t even have access to the airport for three days because of the forensic investigation. You cannot see how bad the damage is to the airport if you can’t get in.”

While he admitted it also took time, three months for the outbound market and a year for many inbound fliers, to feel safe enough to resume using the airport, it now has an excellent reputation for security thanks to the many improvements made.

Verhallen also argued that while the airport does have work to do to attract visitors back, tourist boards must also do their bit to market the destination again.

He added: "It is not so much about the airport, it is about the destination."

Wilken Bellmann, SunExpress’ head of network planning and scheduling, said airlines should also make sure they have properly spread out programmes of routes to ensure even if one destination is attacked, they still have other options for customers.

Meanwhile, bmi regional chief commercial officer Jochen Schnadt said the events themselves can be dealt with as and when they happen.

However, it is the continued uncertainty that does the real damage to the industry he said: “That’s the biggest issue when it comes to topics like terrorism, political instability and Brexit.”