As Norfolk saw its first snowfall of the winter, the county's transport network was thrown into chaos. Schools closed, bus services were cancelled and car crashes closed roads.

And although the snow was barely thick enough to fully cover most gardens, it was five times the amount it takes for Norwich International Airport's runway to close.

Just three millimetres of snow, the thickness of a pound coin, is all it takes for a runway to be 'snow closed' and on Monday, the airport had 15mm. And with the snow on the ground, it was all hands on deck as the airport's army of airfield operators, firefighters and other airport staff all helped clear it.

According to Civil Aviation Authority (CAA) safety regulations, three millimetres is the level at which a runway is classed as 'contaminated' and can lead to aquaplaning and loss of control.

Bearing in mind aeroplanes flying in and out of Norwich International Airport can weigh nearly 80 tonnes, which is nearly twice the weight of an articulated lorry, and can be up to 39m long, it is easy to see why they have to fully clear the snow.

Keith Farrow, airfield operations manager, whose team co-ordinates the implementation of the airport's 'snow plan', said: 'If you think what it's like driving over snow when it's like that, then just imagine trying to take off or land a plane on it. We were always told in training to take a �1 coin out with you and if you lose your pound coin then you know it's time to close the runway.

'We close for two hours and the aim is to get it back to 'black top' when you can see the runway again.'

The team checks the 1,841m by 45m runway at three different parts and will report back. The airfield operations team will coordinate procedures needed to take place while the airport's firefighters will drive the vehicles to get rid of the snow.

There are five tractors with snow ploughs plus five Sicard snow brushes and blowers based at the airport which are used for clearing the snow. There is a further tractor equipped with a vessel filled with de-icer and sprinkling devices, which looks like farm machinery used to water crops, used for de-icing the runway when there is just ice.

It is thought clearing the runway is the equivalent to getting rid of snow on six miles of road, the distance from the airport to Aylsham.

When there is just ice, it takes no more than 20 minutes for the de-icer, 3,200 litres of which is used at a time, to get to work. Last year, 125,648 litres were used at the airport.

And it is not just the ground which needs to be treated – the aircraft themselves need to be de-iced, a job which has to be carried out by a certified member of the team.

Typically, Mr Farrow will get to work at 4.30am and assess the situation. If there is a lot of snow, then the 'snow team' will be called to get in early and when the firefighters start at 5am, they will get to work.

'Our first priority is the air ambulance; we will always make sure the apron and helipad for the helicopter is clear,' said Mr Farrow, who has worked at the airport for 16 years. 'We will then make sure the apron outside the airport, the route to the runway and the runway is clear. It's not just our department though, when there is snow, everyone gets involved to get the airport open as quickly as possible.'

The airfield operations team has only been in post for three years, but has already seen the harshest winter for 30 years and, this year, the earliest snow for 17 years.

During the rest of the time, the runway inspections and bird control. At the first hint of snow, when forecasts are made by their sophisticated airport-specific weather system, they will then refresh their memories of the airport's snow plan and check that all the equipment is in working order.

Andrew Bell, the airport's chief executive, said: 'A lot of people say 'look at Scandinavia, they don't have to close their airports' but often when it's just snow, it's easy to clear but in the UK and in Norwich, we often have a situation where it thaws and re-frosts which makes it more difficult.

'We shut and open, shut and open when we have that situation and then with airports at the other end closing or planes landing in the wrong place, it is easy to see how a six hour delay can become inevitable.

'At Norwich, as we are a small airport, we are really fortunate that we've got a team where everyone knows everyone and they know someone won't let them down, which is fantastic from a business.'

And with their snow plan put into practice earlier than for the last 17 years and their de-icer levels topped up, the airport's team is ready for when the snow returns.