YOU only have to fly into Heathrow Airport and glance out the window to realise how crowded our skies are these days. It can be a slightly discomfiting experience to see the exhaust contrails of countless airliners as they manoeuvre into position waiting in turn to make their approach and landing.

From the ground, the degree of congestion is even more apparent with sometimes only minutes between individual planes in an endless stream touching down or taking off. That more accidents or collisions don’t occur seems miraculous, but this of course is down to the remarkable job done by our air traffic control systems and those who staff them.

Good reason then to sit up and take notice, when those who do this vital job warn that the UK’s skies are running out of room amid a record number of flights. Just as important too is listening to air traffic controllers’ calls for a massive modernisation of the systems that guide aircraft across UK airspace.

The statistics on which controllers base these warnings are staggering. Yesterday 8,800 flights were handled on what was expected to be the busiest day of the year. That was a record number, though the rest of the year is only marginally less busy.

In all, air traffic controllers expect to manage a record 770,000 flights in UK airspace over the summer, up 40,000 on last year. At Glasgow Airport the National Air Traffic Services (NATS) says it has seen a 3.5 per cent increase in passengers since last summer.

There is no sign either that this will slow in the years ahead, with traffic continuing to grow from 2.5 million flights in 2017 to 3.1 million in 2030.

This rise in the number of flights and passengers seems inexorable as our desire to travel grows. The Scottish Government’s plan to scrap Air Passenger Duty (APD) will presumably only make even more of us willing to take to the skies and journey abroad.

At some point, though, existing systems will struggle to cope. According to NATS that point is now upon us. Its warning comes as Westminster launches a discussion to shape the UK’s aviation industry for the next 30 years. Already some £600 million is being spent on new technology to help boost capacity, but NATS insists other measures are needed in tandem with investment if our air traffic control system is to be fully fit for purpose. Changes to the UK’s network of flight paths and routing also need to be implemented and will require considerable government support. All of this, says NATS, is “vital” if control systems are to keep apace with the increase in flights.

The Department for Transport estimates that if airspace management remains unchanged, there will be 3,100 days’ worth of flight delays by 2030, 50 times the amount seen in 2015. There would also be some 8,000 flight cancellations a year.

Meeting consumer demand is one thing, but passenger safety must always be paramount. For that reason the warnings and recommendations from NATS need to be heeded without delay.