Radio 4's pips die at start of PM programme
The computer operating the Greenwich time signal, most popularly known as the 'pips', stopped working on Tuesday evening live on BBC Radio 4.
The absence of the six short tones took the station by surprise at 1700 BST, which was the start of the flagship news programme PM with Eddie Mair.
They returned three hours later at 2000 BST.
Radio 4's PM programme decided to interview BBC broadcast engineer John-Paul Dunkley, who explained the situation.