Posts Tagged ‘cabin pressure’

Cabin pressure on commercial airlines.

November 23, 2008

I have a Casio Pathfinder watch with a built in altimeter. It works based on air pressure. I’ve worn it while I’ve been traveling a couple of times and I like to check it when the plane takes off and as the plane approaches cruising altitude.

Now of course it does not measure actual altitude. For that to happen, the cabin would have to be completely unpressurized. At the same time, one might think that the air pressure in the plane would stay the same throughout the entire flight. If my watch is to be believed this is not the case. This makes sense from a practical standpoint too because otherwise a person’s ears would never pop on the plane.

Here’s some of the data I took. Before they shut the door, the watch said 800′. At take off it dipped to 160′ then went to 420′, 800′, 1300′ and ultimately capped at 5940′ at 31,000′. So assuming a linear relationship between the reading on the watch and actual altitude, the ratio was 1′ on the watch to 5.22′ in real altitude.

On the way back, it capped out at 6280′ so I might have been higher at 32,781′.

I was kind of surprised that it went that high. If the watch is to be believed, spending time at cruising altitude in a commercial airline is like spending time in Denver, CO.

So did I feel like a geek when I was sitting there tracking this data from my watch? Sure, but if you’ve spent any time at all reading this blog, you know that that doesn’t bother me.