Originally Posted by
greenarmy
On routings that would usually be considered illogical, I have found that Amex travel will initially show the same availability as the ITA Matrix, but then error out when attempting to book. Then, searching for the same flights again the the price will have moved up one booking class, which then books successfully. I have no explanation for this.
There is some sort of phantom availability problem, so Amex Travel reserves a seat that doesn't actually exist, then tries to ticket. Even though ticketing fails, the phantom seat remains held for 15 minutes or thereabouts.
So when you perform the search again, it is no longer available and the engine looks for the next booking class.
What you report has never happened to me, but you have given me an idea for next time. If you are only booking for 1 and on the second try it succeeds, then there must only be availability of 1 that doesn't really exist. However if there is a phantom availability of 3, for example, then I would need to make a dummy reservation of 3 seats then begin a new search to see whether the next class shows up, and this would have to be done by trial and error.
With Expedia I find that the initial search shows the phantom availability. However once you select a single itinerary and click onrward, it says the price has changed but the new price (which might be higher or lower than the initial search result) is genuinely available.