The heaviest spring snowstorms for almost 20 years blanketed much of the country yesterday, hampering transport and causing flight cancellations.

At Heathrow as many as 144 flights were cancelled because of the snow, including 62 from the beleaguered Terminal 5. The latest cancellations came after fresh software problems with the new facility’s baggage system caused further misery for travellers.

Air traffic at Gatwick was also at a standstill after both runways were closed from 9am until 11.30am.

The unseasonal weather took hold as sleet and snow descended on Manchester, the North East, the South and North Wales in the early hours, spreading to the Midlands and London. The last time Britain endured similar spring snowstorms was on April 5, 1989.

Temperatures were chilly throughout the day, with a maximum of 6C (43F) in London, Leeds and Norwich. The average for April is about 12C (54F).

A Met Office spokesman said that the sudden change in weather over the weekend was due to winds blowing in from the Arctic on Saturday. “Last Thursday it was the hottest day of the year [up to 18C (64F)] and people were enjoying the warm weather thanks to mild air coming in from the south west,” he said.

The wintry conditions are expected to die down in southern England towards the middle of this week, but sleet and snow showers are forecast for parts of northern England until Friday.

On the roads, drivers on the M56 were among the worst hit. The motorway was closed in both directions near Warrington when a number of cars crashed on sheet ice. A passenger died after a car careered off the A4146 and plunged into the freezing waters of the River Gade. The man drowned in the water-filled car.

In Scotland, rescuers searching for a light aircraft believed to have crashed amid severe weather and poor visibility found the wreckage of a plane with the remains of a person inside yesterday.

The aircraft had disappeared off the radar as it was crossing the Cairngorms, south-east of Glenmore Forest in the Scottish Highlands on Saturday morning.

The alarm was raised when the pilot lost contact with air traffic controllers who had been speaking to him at regular intervals.

Emergency services launched a wide-scale search before the wreckage was discovered on Cairngorm Mountain.

The plane left Carlisle at around 9am on Saturday en route for Wick with only the male pilot on board. The alert was raised shortly before 11am and a search was launched.

About 100 people were involved in the search, which was managed by the Aeronautical Rescue Coordination Centre at RAF Kinloss. Rescuers focused on a 50-square-mile area after witnesses reported seeing a plane and hearing a loud bang.

Michael Mulford, an RAF spokesman, said witnesses reported seeing the aircraft heading south above The Ptarmigan restaurant at the top of the Cairngorm funicular railway. The sighting was followed by reports of a big bang,” he said.

The search was called-off on Saturday night but resumed yesterday morning and involved Cairngorm Mountain Rescue Team and two RAF teams, along with a rescue helicopter.

In Wales, a rambler broke her ankle walking in Snowdonia and had to be rescued by helicopter.