Under standard travel insurance passengers will be compensated for each hour their flight isdelayed over 12 hours, whether or not they eventually catch the flight.

Under an EU directive introduced earlier this year, airlines are obliged to look after delayed passengers. The cost of hotels, meals and drinks must be met by BA. Under the same EU rules, passengers can go home once the flight has been delayed five hours and receive a full refund - but they are strongly advised to inform the airline.

If they choose to give up and go home under the five-hour rule (see above), there is a strong chance that they will not be refunded for accommodation. Tour operators are trying to fly out their customers from other airports.

Should people with flights booked go to the airport today?

BA don't expect to fly a full programme today because there is baggage still in the system and 100 aircraft and 1,000 staff stranded at other destinations. Check ba.com or call BA helpline 0800 767800 before leaving for the airport.

Is it worth arriving early?

Yes. Add an hour to the suggested two hours before a long-haul flight and one hour ahead of a short-haul flight.

How long will passengers have to wait?

No idea. BA will only say they are trying to "keep delays to a minimum".

What facilities does BA have at the airport for stressed passengers?

Extra BA staff have been drafted in to give information. Marquees have been set up outside the terminals to provide refreshments.

What other airlines are affected?

Those that are served by BA ground services - Qantas, Finnair, Sri Lankan Air and British Mediterranean. But the British Airports Authority was unable to say whether this would continue to be the case today. Passengers are advised to check directly with the airline before leaving for the airport.