your original post is unclear
are you suffering from an infection ?
or are you just cold sitting in the plane...that is chilly?
if you are just chilly, turn the heat up, its over your head isn't it?
IF you have a stuffed nose, illness etc, I encourage you to read: SINUS SURVIVAL
It is a book I read 20 years ago and it explains that the ONLY people who have worse problems are coal miners. AIRLINE CREWS are next.
It is a hard life, you are dehydrated, the sinus passages dry out and crack allowing infection to thrive.
There are also FUME issues as others have been writing about.
SEE A VERY GOOD EAR NOSE AND THROAT SPECIALIST, make sure it is not an allergy. Find a Doctor who was a military flight surgeon, he will understand better than anyone else.
In the meantime, take long , steamy showers to help clear your nose.