Fears raised over £269m aerial radar system that will be the 'eyes and ears' of Royal Navy's Queen Elizabeth aircraft carriers

Crowsnest, the most advanced aerial early warning sensor ever built for the Senior Service, is reportedly ‘too sensitive to use’.

The state-of-the-art tech, which will be fitted onto Merlin Mark 2 helicopters, will be the ‘eyes and ears’ for Britain’s two £6.2bn aircraft carriers when on operations.

Sources close to the project have warned IT issues with the sensor array could delay the programme’s rollout, which has already seen flight trials pushed back by several months.

Aerospace giant Lockheed Martin, which is leading the project with defence firm Thales, insisted the hi-tech kit would be ready in time for supercarrier HMS Queen Elizabeth’s first mission next year.

But an insider said: ‘People are running around like blue-arsed flies on this. They’re so far behind on the entire system we can’t train the flight crews because the simulators aren’t ready yet. We’re having to write software for stuff that isn’t even ready.’

The news comes almost three years to the day that the contract to build Crowsnest was announced in Portsmouth.

Revealing the deal, then defence minister Harriett Baldwin said: ‘Crowsnest will provide a vital intelligence, surveillance and tracking system for our new Queen Elizabeth-class aircraft carriers, capable of detecting any potential threats at sea.’

But The News understands software difficulties were reported following a test of the radar just before Christmas.

The situation has worried Admiral Lord Alan West, a former head of the Royal Navy, who said Crowsnest was a critical line of defence for Britain’s £3.1bn aircraft carrier.

‘One of the lessons learned in the Falklands was that we needed airborne early warning systems,’ said Lord West, who served on HMS Ardent in the 1982 conflict. ‘If we would have had that in the Falklands we would never have lost HMS Sheffield.’

Crowsnest sustains 210 jobs, including many in Havant where parts are being developed.

A report by Whitehall spending watchdogs at the National Audit Office in 2017 rated the project as ‘amber’, meaning successful delivery ‘appeared feasible’ but that ‘significant issues’ already existed.

A high-ranking naval officer told The News delays were a worry and warned of a ‘reluctance’ within industry to seek ‘independent help’ when issues arose.

The senior officer added: ‘It will happen, it’s got to happen… Crowsnest is a terribly important part of the whole carrier strike capability.’

Shadow defence procurement minister, Stephen Morgan, has launched a formal probe into the situation and vowed to keep a ‘close eye’ on Crowsnest.

The Portsmouth South MP said: ‘Maiden flights for Crowsnest were meant to take place in late 2018, it wasn’t not until April 2019 that they actually took place.

‘The fact that news has arisen of potentially more delays raises serious concerns over the government’s ability to keep to schedule when it comes to defence matters.

‘The safety of our troops and security of the nation are of the utmost importance, we cannot afford for government to waste time or dither. ‘

It’s understood the system is working through aerodynamic tests ahead of more detailed trials of the hi-tech sensors.

Sources at the Ministry of Defence said software ‘tweaks’ would help to ‘optimise’ Crowsnest, adding Whitehall was confident the radar would be good to go by 2021.

Meanwhile, Lockheed Martin insisted development programmes were ‘designed to iron out potential problems with cutting-edge systems’ before they entered service.

A spokeswoman for the aerospace giant added: ‘We are confident that the Merlin Mk2 helicopter with Crowsnest will be available to support the first operational deployment of HMS Queen Elizabeth.’

The Royal Navy said it ‘continued to work’ with industry partners to deliver the surveillance kit by 2021, with a spokesman adding: ‘Trials are ongoing and we are watching progress closely.’