Of the 50 busiest domestic routes, the two carriers compete directly on only one: Los Angeles to Phoenix, according to OAG, a company that tracks airline routes and schedules.

WSJ: Little overlap in American, US Airways routes

"It's clear that after the increased security measures at European and U.S. airports earlier this year, no amount of high-end investment will solve low-tech problems, " said Duncan Alexander from the Official Airline Guide (OAG).

CNN: Heathrow tests biometrics