Apple's iPad seems like almost the perfect cockpit companion for viewing everything from terminal procedure charts to the number for a local motel–in short, allowing the crew to toss out just about anything that's printed on a sheet of paper. But a closer look at the iPad and its limitations reveals a few caveats that corporate flight departments will want to consider before taking the plunge.

The first question that must be answered, obviously, deals with what the FAA says about the iPad–specifically is it legal to use one in lieu of paper during all phases of flight, including approach and landing? The answer is yes. But as is the case with most straight "yes" answers from the FAA, there are several "buts" attached.

First, you need to be operating under FAR Part 91 to use an iPad in a paperless cockpit. Some third-party companies are exploring ways to modify the iPad for use in Part 135 or Part 121 operations, but that will be tough. The potential issues preventing iPad use in the commercial environment are possible EMI interference with the avionics and the potential for performance degradation during a cabin decompression. Testing to DO-160 standards would be needed for approval, and nobody has done it yet. The iPad's lithium polymer battery also presents a problem for commercial operators, who are unlikely to receive approval to connect to aircraft power. If you're operating Part 135 you can still use your iPad on the flight deck, but you must power it down and stow it for takeoff and landing.

None of these limitations applies in the Part 91 world, although the FAA still suggests that a secondary or backup source of information be readily accessible. This can be paper charts or, even better, a second iPad tucked away in a flight case, ready to power on should something go wrong with the first unit.

What could go wrong? Plenty, it turns out. First, Apple has placed an operating limitation on the iPad for altitudes above 10,000 feet. That won't be a problem in pressurized airplanes, but it means you shouldn't use an iPad above that altitude in a non-pressurized airplane. Also, the iPad is prone to internal overheating, especially if it's carried in a protective case. The device's method for dealing with overheating is to immediately power down and prevent restarting until it has cooled off–not something you want to have happen in a dark cockpit on approach to minimums. And finally, some pilots have admitted to destroying their $800+ iPads by accidentally running their seats back and crushing the fragile devices. (This is one reason why manufacturers of pricier, more rugged EFBs say the iPad perhaps isn't as wonderful a cockpit tool as it might first seem.) 

Besides recommending a backup source of information be carried, the FAA also says operators should carry out assessments of the human-machine interface and crew resource management aspects of using an iPad or other EFB. Further, the FAA recommends pilot training that includes preflight checks, use of all operational functions, and procedures for cross-checking data entry and computed information. The agency also cautions EFB controls that may seem easy to use on the ground might become demanding in flight.

Finally, the FAA says Part 91 operators transitioning to a paperless cockpit should undergo an evaluation period during which paper backups are carried. During this trial period, the operator should validate that all of the features and functions of the EFB really are as reliable as the paper they replace.

The guidelines for iPad use in the cockpit are spelled out in AC 91-78, a document that provides additional information for operators seeking to transition to paperless operations using Class 1 or 2 EFBs. Dated July 20, 2007, the AC was created before the iPad was even a glimmer in Steve Jobs's eye, yet clearly the agency recognized that devices like it were coming.