AIR traffic controllers sounded the alarm on cost-cutting yesterday following an IT collapse that left planes unable to enter British airspace, take off or land.

Safety chiefs launched an official probe yesterday into Friday’s meltdown — branded a mere “glitch” by bosses — that came almost a year to the day after a 2013 systems freeze.

The Civil Aviation Authority (CAA) has set up an independent investigation into the incident that will look at the “level of resilience” in Britain’s air traffic systems, run by part-privatised Nats.

Nats chief executive Richard Deakin, who is in line for a £1 million payout this year, said the systems failure was triggered by a previously unknown bug contained in computer code dating back to the 1990s.

But air traffic controllers’ union Prospect said a fresh wave of planned cuts would hamper attempts to prevent a repeat of the “unprecedented scenario.”

Prospect national secretary Steve Jary warned of low morale among staff following redundancies ahead of a five-year plan to slash spending by a further 22 per cent at the profit-making operator.

Business Secretary Vince Cable joined mounting criticism of Nats, which reported profits of £157.5m last year, accusing it of “skimping on large-scale investment” and running “ancient computer systems.”

But Mr Jary said the minister had lost “command of his brief,” explaining: “The CAA is the government’s regulator and the government’s 49 per cent shareholding is managed by Mr Cable’s department.”

Fifty-one per cent of Nats Holdings, formerly the National Air Traffic Control Service, was flogged off in 2001 by the last Labour government.