What's up with this battery life?

[trpnmonkey41]

I am usually around 4 hours with airport on and brightness on full but if I am on a flight i turn off sound and airport and have my brightness lowered 4 or 5 notches to give me over 5 hours

 

[TylerMoney]

when I'm not plugged in, my brightness is usually all the way down (off and on) and I get about 2.5-4 hrs....once agian...depending on what I'm doing.....I'm pretty happy with it...I don't know when the last time I let it go all the way down was though....it could be getting a lot more than I think...cause it goes up and down...for the things I'm doing are constatntly changing...