Flight, train and ferry schedules in Scotland have been wrecked by Storm Barbara, with high winds causing the cancellation of links to Orkney, Shetland and the Hebrides.

Travel alerts have been issued for all 26 Caledonian MacBrayne ferry routes, with links from the mainland to Barra and Stornoway among the cancellations. Northlink Ferries has advised people not to attempt to travel between Aberdeen, Orkney and Shetland before Christmas. Loganair has cancelled a number of flights and rescheduled many departures to avoid the worst of the bad weather.

Some Irish Sea ferries have been disrupted, particularly between Scotland and Northern Ireland.

Elsewhere in the UK, the busiest day for outbound travel of the Christmas season has been going fairly smoothly — except for around 500 people flying to Malta. After an apparent hijacking of a Libyan aircraft to Malta, the Foreign Office said: "Some flights have been diverted or cancelled and further disruption is likely."

Simon Calder on London Live discussing the great Christmas getaway

Three flights from the UK, with easyJet and British Airways from Gatwick, and Ryanair from East Midlands, were diverted to Sicily. The authorities in Malta say “airport operations have been resumed” and the planes were expected to complete their journeys about two hours behind schedule, which will cause some knock-on delays.

For many of the UK's biggest airports, including Gatwick, Manchester, Stansted, Edinburgh and Luton, today is the busiest day of the festive season. At Heathrow, 119,000 departing passengers are expected — two per second during the airport’s operating hours. But the total is still 35,000 short of the busiest-ever day, in August last year, so some slack remains in the system.

Late on Thursday, British Airways and the Unite union reached an agreement in a dispute over pay for some Heathrow-based cabin crew, suspending a strike planned for Christmas Day and Boxing Day.

BA told passengers: “As previously announced we will be running our normal schedules on those two days and if you are travelling with us, we look forward to welcoming you on board.”

But pilots working for Virgin Atlantic have started a work-to-rule in a dispute over union recognition.They say they will work “strictly to contract”, which could involve refusing to be flexible in the event of disruption. Virgin Atlantic said it expects flights to be unaffected.

On the railways, the main problems are in Scotland. ScotRail services have been severely disrupted, with multiple cancellations on Edinburgh-Perth, Glasgow-Oban and Inverness-Kyle of Lochalsh, as well as the Borders — with rail tickets valid on some Citylink buses.

All the long-distance operators say today is their peak day. That includes Eurostar, which runs trains through the Channel Tunnel, Virgin Trains on the east and west coasts, CrossCountry and East Midlands Trains.

There is particular pressure on GWR, which runs trains west from London Paddington, and on Greater Anglia services east from Liverpool Street to Colchester, Ipswich and Norwich. Engineering work means both these stations will close at midnight, with complicated alternative journeys involving Tube trains and buses.