Seven Pounds Per Minute

When I was a baggage handler for Canadian Airlines, I never really understood why the pilots would request a “plug in” rather than simply use the auxiliary power unit (APU) at the back of the 737-200s. It was a pain for all involved (mostly us, so it was probably a case of us being lazy *g*) and I always thought it made us look a bit like amateurs. This was especially true since back then, as is the case still, passengers walked out onto the ramp and up the stairs. So essentially they saw everything that happened on and around the ramp.

Today, I finally understand. I read Captain Dave’s entry on their aircraft’s weather radar in which he mentions that their APU burns 7 pounds of fuel per minute. Yes, per minute. As a general aviation pilot I find that number fascinating because if you get good tail winds and a perfect day, you can cruise at 125 knots in a Piper Warrior for less than 1 pound of fuel per minute. Yup, a small aircraft can fly for a seventh of what it takes to run the APU of a large passenger aircraft. I don’t know why but I just find that amazing. Oh, and now you perhaps understand why the airlines are legitimately complaining about the high cost of fuel.

1 comment »

1. By david about 3 hours later:

   
   
   I think he also mentioned that each of the main engines idles at 40 lb/minute -- that's 350 gph of Jet-A just to idle a big jet engine. Yikes!