Why did tech ground Heathrow baggage?

The exact cause of the technical fault that caused two days of luggage chaos at Heathrow remains unknown.

Heathrow's Terminal 5 in pics

♦ Photos: Passenger's eye view of Heathrow Terminal 5

♦ Photos: Heathrow's T5 tech ready for take-off

♦ Photos: Technology at the heart of Terminal 5

♦ Photos: Heathrow's Terminal 5 comes alive

♦Photos: Inside Heathrow's Terminal 5

Airport group BAA has still not been able to pinpoint the exact software glitch that left 6,000 British Airways (BA) long-haul passengers unable to take hold luggage on flights.

The error happened early on Tuesday this week and led to two sorting systems at Terminal 4 going down until Thursday.

BA advised economy passengers not to travel with any more than two items of hand luggage and offered refunds to all affected passengers.

BAA said it expected to pay compensation to BA over the failure of the system.

A spokesman for BAA said: "We have two sorting machines, one is a redundancy, and we have never had both go down before, that is why it was such a significant problem for us. We are still analysing exactly what caused this at the moment. BAA would like to sincerely apologise to these British Airways passengers who have had their travel plans disrupted."

Although normal service was resumed for passengers on Thursday, the BAA spokesman said continuing problems meant some baggage was still having to be directed manually at T4 behind the scenes.

A BA spokesman said: "We were not able to accept hold baggage for World Traveller and World Traveller Plus passengers. Our main focus has been on getting the systems up and working again."