From personal experience: no problem. You can even take the window seat as you won't have to get up to use the lav

When you empty your bag, you open the valve on the bottom and the water flows out. What's left is not a vacuum, but the bag does not open up and take in a lot of air; it's mostly just an empty bag. Then you close the valve (it sure sucks when you forget this step! ) and basically have an empty bag. It gradually fills with urine while you fly - the liquid isn't going to change much in volume. So worries about pressurization, etc. seem ill founded. In fact I took a number of flights with my Foley and had no trouble (eventually I had prostate surgery and no longer needed it).

One thing to note, however, is that the hose from your genitals to the bag has to be oriented properly as it's only gravity flow which drains your bladder. Be wary of kinks in the hose due to the cramped sitting on planes and make sure that the bag is below your bladder at least some of the time.

Of course if the bag fills just go to the lav and empty it.

Sit back, relax, and enjoy your flights