You could compare your $/mile to the airline's yield ($/revenue mile). Each airline publishes their yield quarterly and annually, and the DOT has it also. That way, you'll know if you're paying average, above average or below average per mile.

I think most airlines except WN have yields around 10-12 cents. If you're averaging 14 cents, that's pretty close, especially on US, which has higher yields but higher costs.

Even better would be to get the airline's yield on the routes you actually fly. That would be a better comparison. However, I think that's proprietary, but you could look around the DOT's web site and see if you can find anything.


Here's something else you can do with your numbers without resorting to the DOT. 14 cents is your average. Fine. But what's the variance? If you're buying cheap roundtrips and last minutes, your variance is probably pretty high. If some of your routes are cheap and some are expensive, the variance will be even higher.

The point of variance is so that you can compare two sets of numbers in which both have the same average. Generally speaking, higher variance is bad.

To calculate variance, add up for each trip taken: (cost is per mile)

(actual cost - average cost)^2

which would be in your case:
(actual cost - 0.14)^2


Take that total and divide by the number of trips. That is the variance.

Take the square root of the variance, and you have the standard deviation. Standard deviation (s.d.) is in $/mile, just like the average. Variance itself is not terribly useful; standard deviation is a useful figure.

I'll wager that your s.d. is 10 cents.


If you want, send me the spreadsheet (price and miles for each trip). I do this kind of crap all the time; it's a cinch!

[This message has been edited by JS (edited 09-28-2001).]