Dutch Harbour Airport in Alaska is flanked by land on both sides. In winter, the runway can also be frozen and get covered with a thick blanket of snow

Coastal regions can throw up another problem - mountains.

At airports such as Funchal in Madeira, the landing strips are built parallel to the mountains, which is incidentally how the plane must be flown before it makes a landing.

While the precise positioning for the approach is difficult enough - everything is done by eye rather than with the help of navigation instruments - the airport also has to contend with strong winds from the Atlantic ocean.

It's one of the airports where pilots need additional training to be permitted to land a plane.

Similarly, at Dutch Harbour in Alaska, the coastal approach is flanked by land on both sides before leading back into the sea.

As well as navigating around the land formations, pilots also have to cope with freezing temperatures and heavy snow fall for several months of the year.