Aircraft lining up for takeoff at Washington Reagan National Airport.

Flying Blue, the frequent-flier program of Air France/KLM, has banned customer service agents from revealing the codes the airlines use when booking awards or upgrades. If you ask them, they will tell you it’s none of your business. Is this misplaced paranoia or do carriers have the right to keep that information secret?

For smart and sophisticated travelers, the importance of having access to raw airline data cannot be overstated. Benefiting from that access has changed my travel life — it has ensured that I always pay the lowest possible fares and fly in comfort and luxury at the same time. Booking codes, of course, use letters of the alphabet.

Earlier this month, I needed to verify the codes Air France and KLM use for awards and upgrades for my upcoming book, because Flying Blue is making some changes beginning June 1. So I called the Flying Blue North American call center outside Toronto. An agent called Henry Esteban refused to share the information, saying he and his colleagues had specifically been forbidden by management to do so.

I’d never heard such a response to the same question I’d asked so many times before at other airlines, so I requested to speak with a supervisor. Esteban resisted repeatedly, which also surprised me given my Platinum elite status, but eventually he put me through.

The supervisor, Roberto Quote, was just as vehement in his refusal to discuss booking codes. He insisted that was private company information and customers had no right to know it. If you wonder why I didn’t turn to Air France reservations agents, that was actually my first call — but they said they knew nothing about awards and upgrades and referred me to Flying Blue.

In 2009, I wrote about the challenges to airlines presented by the transparency of their data on the Internet. I also wrote specifically about the public availability of award data, which some carriers wanted to control. However, simply identifying the codes used for awards and upgrades has never been an issue — until now.

Although no carrier is legally required to disclose those codes publicly, I have a hard time understanding Flying Blue’s thinking. Does its management really believe that kind of information can be kept secret in 2011, with all the blogs out there and websites like FlyerTalk.com and Milepoint.com?

It may be time for the program to focus on more meaningful and useful subjects in the training of its customer service agents.

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