Scores of flights across the UK and the rest of Europe have been cancelled as the continent is hit by a blast of freezing weather.
British Airways has grounded more than 60 short haul flights to and from Heathrow in a bid to preserve the punctuality of other flights.
But a number of other flights from the London airport were delayed nonetheless.
The airline is offering passengers booked on short haul flights between Monday and Friday the chance to re-book for travel on a later date up to March 21 free of charge.
A spokesman for the carrier said: “We are sorry that the weather this week is likely to lead to some delays and disruption to our schedules.
“It is likely at times we will have to proactively cancel some services and re-book customers on to alternative flights.
“Customers on cancelled services can also claim a full refund if they no longer wish to travel.
“We are sorry for the potential disruption to your travel plans and are doing all we can to minimise the effect the poor weather may have on our flights.”
Airports in Rome, Stockholm and Bergen were among those to suffer significant disruption to departures as Europe is hit by a blast of Siberian weather.
Ryanair cancelled almost 50 flights departing or arriving from the Italian capital, including some serving the UK.
EasyJet said its UK flight schedule was unaffected by the weather.
More than 70 flights travelling to or from the Canary Islands were disrupted when the region was hit by strong winds and rain on Sunday.
Passengers were forced to spend the night at the airport waiting for flights.
Travellers suffering from disruption due to bad weather are not entitled to compensation under EU rules, but airlines must provide assistance such as free access to phone calls or emails, meals and accommodation if required.