Originally Posted by Flaflyer

You also have to watch out if you are on a long flight with meal service. The little ounce tubs of salad dressing with the foil lids are sealed at the factory near sea level. At altitude they are under pressure and the lid bows out like a dome. (along with the lids of the butter, jelly and juice tubs in the meal trays) Point it away from you when opening, unless you are one of those who like shaking your cola cans just before opening.

Next flight, make a Poor Man's Altimeter like I do. (there is not much else to do below 10,000 feet when your electronics must be turned off. ) The pressurized cabin altitude in a jet is about 6000 feet.

Carry an empty thin wall 500 ml disposable water bottle thru TSA or buy an overpriced on in the terminal and hope it does not get stolen in a TSA Gate Sweep. Use one with a regular screw top cap, not a pop up sippie type cap as they do not seal as tight. At max cruise altitude drink all the water and cap very securely. Make sure the bottle is normal shaped with no dents etc. Watch it as the plane descends. Around 6000 feet the bottle suddenly begins to crush. You will be surprised how much it crushes by the time you land. (assuming you are landing near sea level and not in Tibet or Bolivia)