A third of UK flights could be delayed by more than half an hour unless airspace is modernised, the Transport Secretary has warned.

The skies are becoming “increasingly congested” and punctuality could be 70 times worse by 2030, Mr Grayling said.

He told the Aviation Club in central London that this would be damaging for passengers and local residents as aircraft continue to be “held needlessly in stacks above urban areas”.

The Department for Transport (DfT) believes new technologies can improve the way the UK’s crowded skies are managed.

A public consultation on proposals to boost efficiency was held earlier this year and the Government’s final plans are expected to be published in the autumn.

Mr Grayling said: “Our aircraft are fitted with the latest satellite navigation technology, but our airspace arrangements are half a century old.

“Without action, by 2030 total delays due to inefficient use of airspace capacity could be 70 times more than in 2015.

“We’d be looking at one in three UK flights departing over 30 minutes late.”

The UK has the third largest aviation network in the world based on the number of seats available and the distance flown, behind only the US and China.

Chris GraylingTransport Secretary Chris Grayling says airspace congestion is a major problem (David Mirzoeff/PA)

But the flight paths used by airlines are equivalent to “driving across the UK without making use of motorways or satnav”, according to the DfT.

Modernisation of airspace could allow aircraft to make greater use of smooth, continuous descents and climbs, meaning they would spend less time at low levels where they create more noise and are less efficient.

This would reduce the need for conventional orbital holding, known as stacking.

But redesigning flight paths is a contentious issue as it can mean some communities currently unaffected by aircraft noise are put under flight paths.