747-400 Cockpit quiz...
 

Could somebody please identify that white box with two "slots" in it at the linked picture upper left corner? (Behind the observer's gasper)
Photos: Boeing 747-436 Aircraft Pictures | Airliners.net

samples air from cockpit for temp modulation.
times when cockpit temp is difficult to maintain then take off cover and clean foam type insert.

Oh... that was quick and precise, many thanks,
b

Do I win a prize for knowing that and the name of the Captain? :)

I've anticipated a reply like this... No secrets on this forum... I like it.
Cheers,
b

...at last the Britts' got some snow this winter to fulfil their fantasy...

Yep, standard stuff for any A/C temperature control system. A sampling fan draws air through a filter (foam in most Boeings) over the temperature control and indications sensors. Failure of the fan or blockage of the filter causes the sensors to mis-read. Single sheet loo paper is a good test :rolleyes: