US winter flight cancellation rate the worst in last 20 years

It's official: This North American winter was the worst for US fliers in the 20 years that the government has been collecting data.

During the first three months of this year, US airlines cancelled 4.6 per cent of their flights, the Department of Transportation announced on Tuesday.

The worst winter before this was 2001, when 4.4 per cent of flights were scrapped.

Mother Nature is mostly to blame, with a relentless wave of snow and ice storms paralysing airline traffic across the nation.

But airlines are also quicker to cancel flights these days, sometimes a day in advance of a storm.

The shift in strategy came in response to new government regulations, improvements to overall operations and because cancelling quickly reduces expenses.

In May 2010, a new DOT rule took effect prohibiting airlines from keeping passengers on the tarmac for three hours or more.

So, airlines now choose to cancel blocks of flights to avoid potential fines of up to $US27,500 ($A29,800) per passenger or $US4.1 ($A4.38) million for a typical plane holding 150 fliers.

In March, JetBlue had the highest cancellation rate among the bigger airlines: 2 per cent of flights.