"For at least the last 20 years, they have underinvested in their systems," he said of the industry.
Parts of the computer system used by American date to the 1960s, he said. It has been adapted since then, "but its basic architecture, its design, is pretty old."
Switching to something new is harder for airlines than for other industries because their first priority is to keep their operation running smoothly and safely, he said.
AMR and US Airways hope to complete the merger by September and create a giant that would surpass current industry leader United in passenger miles. Airline mergers are always difficult, and one of the trickiest parts is combining technology systems.
When the systems of US Airways and America West Airlines were combined in 2007, chaos ensued. Hundreds of check-in kiosks didn't work, ticket agents were swamped, and flights delays lingered for days.
United's reservations system failed on several days last year after it converted to the one run by merger partner Continental Airlines. The CEO was forced to apologize.
Even if flights operate on time, there can be other hitches when systems are merged. At United, upgrades for elite members of the frequent-flier program weren't handled properly, and flights booked with miles weren't always ticketed correctly. Those mistakes were especially upsetting to the airline's most loyal customers. It's one thing for one flight to be late. For many veteran fliers, it's worse to constantly worry about upgrades.
Airline technology is notoriously complicated because so many pieces of the system rely on each other for information, said Emre Serpen, a consultant at InterVistas who works with airlines on technology issues.
Passenger information goes into the system and tells gate workers whether all the passengers have arrived. The same information is used to calculate the weight of the fully loaded plane. Flight dispatchers, who may be in a command center across the country, use the figures to order the right amount of fuel — too much fuel adds weight and reduces mileage.