The airline's pilots can replace 40 pounds of company manuals and maps with a pair of iPads (one for each pilot), along with a long-life battery to keep the iPads powered for 24 hours.
Because both pilots are carrying iPads with backup batteries, the FAA feels this is as redundant as paper manuals.
So far American has approval for the 777, 737, MD-80 and is just awaiting approval for the 757/767 fleet. Hopefully, this will be just in time for my return to that airplane, as once you use this setup, you won't want to go back to the paper.
To get that approval, American had to have the iPad tested in a hypobaric chamber to simulate how the device would handle during a rapid decompression. They also had to arrange for mount testing with the FAA, which is ironic since our manuals weigh far more than the iPad and aren't secured in place. Many takeoffs have resulted in a book or two sliding off the side table and onto the floor.