Premier Date: March 15, 2006
The amount of helium required to lift a person off the ground (let alone the raft itself) is prohibitively immense, and such a raft of adequate size would be quite flimsy. In fact, the final test of the raft had to be aborted because of an unbalanced release of the ties, causing Adam to become entangled and destroying the raft in the process.
It was found that cell phone signals, specifically those in the 800-900 MHz range, did intefere with unshielded cockpit instrumentation. Because older aircraft with unshielded wiring can be affected, and because of the possible problems that may arise by having many airborne cell phones "seeing" multiple cell phone towers, the FCC (via enforcement through the FAA) still deems it best to err on the safe side and prohibit the use of cell phones while airborne.