Yesterday, I got gas after coming back from the post office to mail something I’d sold on eBay. I was annoyed that it was a $1.97/gallon. I filled up Arthur, something I’ve gotten reasonably good at doing finally. If I just stop after the automatic shutoff, it’s anywhere between 1.5-2.5 gallons shy of full. Unfortunately, it’s really difficult to fill all the way up without getting gasoline everywhere. Which is why you have to actually pull the nozzle out and watch the level in the tank… much like filling up an airplane.

This morning was cloudy and rainy, but it’s been clearing up this afternoon. I was trying to decide whether to go for a drive in Arthur or ride my bike. I decided to ride the bike since gas is so expensive. When I came back about 45 minutes later, I smelled gasoline outside my apartment. It took me awhile to figure out…

See, gasoline has a very noticeable tendancy to vary its volume in response to temperature changes. Water, for instance, doesn’t do this. Gasoline does– something most people aren’t very aware of. Most pilots know this. If you fill an airplane on a hot day, it won’t take as much fuel as on a cold day. This is why when it matters, fuel is measured by weight. The CRJ-600s I rode around on as a flight attendant can hold aproximately 14,500lbs of fuel. But on a 110 degree day on the ramp at DFW, they’re never going to get 14,000lbs in it. That’s a significant amount of fuel. It’s not as significant when you’re talking about a Cessna 172 that can only hold 21.5 gallons of fuel in each tank. (Only 20 gallons per tank are usable)

Gasoline was slowly coming out from under Arthur’s fuel cap. Still, something didn’t make sense. It felt just as cold outside as it was when I filled up Arthur yesterday. Then it hit me. As Nathan is fond of pointing out, the gas tank is inside the cab. With the sun shining and the windows all sealed tight, it was plenty warm inside the cab and getting warmer.

So I went for a drive with the windows down after all… cooled it off and used some of that gasoline.