“I have a drone on my airfield” – a statement that welcomes passengers to the latest dimension in air-travel disruption. Words of despair from the chief operating officer of Gatwick airport in the busiest travel week of the year.

Elsewhere, many thousands of stranded and inconvenienced passengers turned in frustration to social media in an expression of crowd-sourced outrage. How could this happen? Why is it still happening over 12 hours after Gatwick’s runways were closed to aircraft, why is an intruder drone – or even two of them – suspended in the bright blue sky above the airport, apparently visible to security staff and police who remain quite unable to locate its source of radio control?

Meanwhile, the UK Civil Aviation Authority, overtaken by both the technology and events, is reduced to sending out desperate tweets warning that an airport incursion is a criminal offence and that drone users should follow their new code of conduct.

Yet this is not an unforeseen event. It was inevitable. I’ve both written about the risk and warned an international airports conference in 2015 that this was “a clear and present danger” to their operations. Now the UK’s second-busiest airport is closed and demonstrably helpless in the face of a small piece of flying technology weighing much the same as a bag of sugar.

Drones have been used before to disrupt airports. In Dubai it’s become almost commonplace – and there are frequent incursions at the UK’s smaller airports. The only surprise to date is that there hasn’t yet been a serious incident in UK airspace – as happened with a Boeing 738-800 belonging to Aeroméxico on 12 December on the final approach to Tijuana in Mexico.

Fast-evolving drone technology has introduced an easily achievable and single point of failure into an already overloaded air-transport network. But aside from the exploration of the terrorism implication, the authorities appear to have been slow to take notice, other than introducing a relatively modest criminal penalty for bringing a major airport to a complete halt. In many respects, the CAA treats this as nearly equivalent to a small aircraft pilot accidentally infringing on the tightly controlled airspace that surrounds an air-traffic zone. But if you are one of the more than 10,000 passengers affected by the disruption, facing the loss of your Christmas holiday, your view of the legal sanction may be very different.

Outside Rochester airport in Kent, there’s a PC World that is a cornucopia of the latest drones, with prices ranging from a few hundred pounds to a thousand or more. The last thing on the buyers’ minds, I would suggest, is the CAA code of conduct. These are seen as just another modern consumer device, like cheap green laser pointers that can cause real mischief and occasionally, almost unimaginable chaos in the hands of the malicious or the simply irresponsible.

But it’s not that airports, with their huge security budgets, don’t have access to countermeasures. They do. “Drone rifles” are now widely available to the military or the police and Donald Trump’s Secret Service contingent never travel without one. These devices, pointed in the direction of an intruding drone threat simply disable it, causing it to land on its autopilot. End of story.

Why then, you may ask, have the police or the airport at Gatwick not deployed a drone countermeasure if, as stated, they know where one or even two drones are above the airport? It’s a mystery and leads one to wonder whether after all the warnings, they simply didn’t take the threat of a drone bringing the airport to a complete halt seriously enough. Worse still perhaps is the terrorist threat posed to airports by the consumer drones that Isis has used to dramatic effect in Syria and Iraq.

Perhaps it’s simply a matter of luck that both Heathrow and Gatwick were not both closed down on the same day before Christmas. But they might have been and still may be at some point in the future. It’s time to start taking this new threat very seriously indeed.