How to prepare an 'Arctic runway'

Polar explorers Pen Hadow, Ann Daniels and Martin Hartley are trekking across the Arctic, taking measurements of sea-ice thickness as they go.

The team hopes its data - primarily now from drilling following the failure of a mobile radar unit - will help scientists better understand the changes taking place at the highest latitudes.

Here, Pen Hadow describes how to prepare a runway in the middle of the Arctic so that a re-supply plane can land.