This is the unusual moment a pair of diligent pilots were seen leaning out of a cockpit to clean a plane's windscreen.

A traveller waiting in the departure lounge at Don Mueang International Airport in Bangkok, Thailand, spotted the aviators cleaning the windows.

Footage shows one pilot wiping the aircraft's glass panel with a cloth before his co-pilot joined and leaned out to help scrub the windscreen on April 30.

The pair then returned to their seats inside the cockpit of the Boeing 777 operated by Thai Lion Air as they awaited passenger boarding.

Pilots do not usually clean the aircraft windscreen themselves, as this is normally carried out by ground staff or maintenance crews during standard servicing procedures.

However, if they feel their vision would be improved by giving the glass a quick wipe, they may sometimes lean from the cockpit window to do it themselves.