The British Army’s troubled Thales Watchkeeper WK450 programme appears to have suffered a fresh setback after the revelation that the unmanned air vehicle was grounded earlier this year following a pair of accidents.

No details of the crashes – the third and fourth involving the Watchkeeper – were released at the time by the UK Ministry of Defence, but have now been disclosed.

Speaking on 11 September, Rear Adm Jon Pentreath, who overseas the surveillance UAV as chief of Joint Helicopter Command, said “Watchkeeper is back in the air again” following a temporary grounding.

The MoD confirms the incidents took place “over Cardigan Bay” off the west coast of Wales. “We paused Watchkeeper flying for a short period whilst conducting initial investigations, but resumed flight trials in early July” it says.

“Service inquiries into the specific incidents are ongoing as we look to learn all we can from the events.”

Although investigations into the crashes are ongoing, defence officials believe a “combination of factors” is to blame.

Despite the resumption of flights, tighter restrictions are now in place on Watchkeeper operations, particularly affecting the meteorological conditions in which it can fly.

Full operational capability for the Watchkeeper is due to be declared later this year or in early 2018.

Two previous crashes of the UAV, in 2014 and 2015, were blamed on a combination of control software and pilot error.

The UK intends to procure a total of 54 Watchkeepers under a £1.2 billion contract, for operation by the Royal Artillery’s 47 Regt.