British Airways Boeing 747 aircraft parked at London's Heathrow airport.

One of this column’s goals is to point out nuisances in the air travel system and help you avoid them or minimize their negative impact. As I welcome the many readers who have become subscribers since my book, “Decoding Air Travel,” came out, I’d like to tell you about one such nuisance.

As my regular readers are well aware by now, I always know in what booking class a future ticket will be issued. I search for availability in that booking class and choose flights with available seats. That’s why, even if I have to make a reservations with an agent on the phone, I know how much the ticket will cost before I make the call.

The only time when this strategy fails is when I need an airline to book a seat on a partner-carrier, and the ticketing airline’s agent can’t “see” availability in the respective booking class in the partner’s inventory. I’m not talking about award seats, so comparisons with United’s StarNet blocking practice would be misplaced — this is about revenue tickets fully paid for with money, not miles.

So why don’t agents see availability in a certain booking class or fare bucket on another carrier? It usually has to do with the Global Distribution System (GDS) they use to book tickets. For example, United currently uses Apollo and Lufthansa Amadeus. Although most of the time the two systems show identical data, there may be occasional delays, and a United agent may not see a Lufthansa seat displayed as available on Amadeus.

I can explain most things in the airline world, but British Airways and Iberia posed a new challenge last month that left me utterly perplexed. The two companies and Oneworld alliance members merged last fall, and they both use Amadeus, which would mean that their agents should see the same data on their screens — at least it would mean so to a logically thinking person. That person, however, would be wrong.

I was booking a trip for a friend, who is also a client, from Washington to Africa in Business Class. He has Gold status with BA and wanted to fly BA to London and connect to Madrid and on to Africa on Iberia.

According to the BA website, his destination doesn’t exist — many airline sites don’t show cities they don’t fly to, but it’s high time BA added the airports served by Iberia now that they are one company. Fine, I thought, what’s the other option? Naturally, the Iberia site, as the Washington-London BA flight could be booked as an Iberia code-share. There was one problem, though: Iberia priced the desired itinerary almost $4,000 higher than BA.

Clearly, the only thing left to do was to call BA — an exercise I don’t look forward to because of the long waiting time. When I finally got an agent at BA’s call center in Jacksonville, Fla., she said there were no available seats in Business Class on Iberia’s flight from Madrid to the African destination, which I’m not revealing on purpose.

I thought she was joking. Amadeus was showing seven open seats in the full-fare Business booking class I needed, which is J class on Iberia. BA doesn’t code-share that particular flight, so it had to be booked a “true” Iberia flight number.

I started scratching my head. How was it possible for BA’s Amadeus-powered computers to show no seats at all when there were seven? Perhaps it had to do with the point of sale (POS) — I’ve seen airlines alter the inventory on the same flight, depending on where you view the data. But both the BA agent in Florida and I were in the U.S. Still, I changed the POS from the U.S. to Europe, but there was no difference. I also called Iberia to verify the seats were indeed available, and Iberia’s agent in Miami saw exactly what I did.

The BA agent tried to explain the discrepancy by telling me that Iberia hadn’t “given” BA any seats, but I immediately asked her to stop making stuff up. There is no such thing as one airline “giving seats” to another — anyone can book a seat if the operating airline has published it in its inventory, even if the second carrier is not a partner of the first.

Despite all the mystery and frustration, that wasn’t the end of the world, I thought. I asked the BA agent to waitlist the segment in question. My plan was to call back in case another agent could find a way to “see” the seat I needed, and if that failed, I would call Iberia and have them clear the waitlist, since their agent had confirmed availability earlier.

I’ve done just that with Star Alliance carriers several times. For example, Singapore Airlines tends to be stingy with D class availability on intercontinental flights. Star uses D class on round-the-world Business Class tickets, and Singapore deems those fixed fares too cheap. If I issue a ticket with another carrier, it might waitlist a Singapore segment. I’d then call Singapore and ask a supervisor to clear the waitlist if he or she found it appropriate. I’ve also done that with Lufthansa, Japan’s All Nippon Airways, South Korea’s Asiana and others.

However, that simple procedure proved too hard for the merged BA and Iberia, both of which use Amadeus, as mentioned earlier. When I called Iberia back, the agent saw available J seats but said that only BA could clear the waitlist. Except that BA couldn’t, because its agents saw no seats. The Iberia agent’s claim sounded odd, because Iberia controls its own inventory, and I thought it had a way to indicate electronically to BA that a waitlisted seat can be confirmed. So I called back but got the same response from another agent.

Then I phoned BA again and asked the agent to call Iberia, hoping the waitlist could be cleared that way. After keeping me on hold for about 20 minutes, the agent hung up without coming back on the line.

I’d had enough of both carriers’ nonsense, so I took matters in my own hands. I called Iberia yet again and asked the agent to book just that one segment in question separately from the original booking. He gave me the new record locator, and I called BA again, explained the situation and asked that agent if she could incorporate the second booking into the initial one and issue the ticket that way.

She couldn’t but a supervisor was able to do it. Part of me was grateful, but the other part was frustrated that the previous BA agents I’d spoken with never offered me the option I eventually thought of, and wasted hours of my time.

What sort of a merger have BA and Iberia created if they can’t perform the most basic airline function — booking available seats on each other’s flights?

Related stories:

British Air loses bags on $12,000 ticket

The peculiarities of airline agent training

American’s antiquated ticketing process

United fliers hit by pre-merger changes