I've flown with them before. Be sure to take a decongestant an hour or so before boarding. If you have a headache with it, take something for the pain (I use Excedrin... the caffeine is a plus). Make sure you drink lots too to keep from drying out (doubt you will NYC-ORD unless you get stuck on a tarmac). Long ago they had a prescription Entex LA that worked good for me, but they don't make it anymore AFAIK. The OTC Mucinex is probably the closest you'll find now.
As usual, consult your doctor or pharmacist.