Flight Time Calculator lets you enter your total airtime and converts it to decimal form, so you can log your flight hours quickly and accurately. With this app, you can see your departure and arrival times in your local time zone as well as in Greenwich Mean Time, so that you have a frame of reference.
As soon as you open Flight Time Calculator, you can start entering your flight times. Just tap the take-off time section to enter that info on the rolling scale, and once you're back on the ground, tap landing time to enter that in the same way. There is no way to adjust the time zone, so you have to be sure to enter all takeoff and departure times in your local time. At the bottom of the screen, there is an information icon that you can use to access the settings menu. From there, you can turn 24-hour mode on and off, and you can enter an e-mail address that you'd like your flight time reports sent to.
This app is free, and there's an in-app purchase that removes ads for $0.99. It's hard to see why that would be worth it, though, since there really aren't many ads, and those there don't take away from the user experience much. The calculator works well, and provides a convenient readout, so you can log your total flight time accurately without having to calculate anything, yourself.