Flying With The Parker 51 Vac

[Bristol24]

I will be on a long trip coming up soon and want to take along a couple of fountain pens. Generally for a flight, I only have one pen inked and the others packed away empty. In the past, I have flown with either a Hero 616 (no big deal if it gets lost) or a Parker 21 Special. This trip, I would like to take one of my Parker 51s, specifically a 1945 '51 vacumatic. With my Hero 616 and the Parker 21 Special, all I did was make certain the pen was nib-up for the climb to altitude and again for the descent (and not in my pocket). I had no problems but both pens are aerometric fillers. I am a bit concerned that the vacumatic '51 might behave differently. Has anyone flown with a '51 Vac?