Originally Posted by
3Cforme
I'm interested in that mechanism. I have found itineraries (non-stop, so it's not a married segment thing) found by ITA Matrix that did not found inventory on delta.com or aa.com. But Orbitz has been able to ticket them at the ITA Matrix price, and tickets were honored for travel.
There's a difference between searching for available inventory and booking it once found. It's entirely plausible that ITA has better searching algorithms than the airline websites (airline inventory searches are a notoriously difficult computational problem to solve), or that caches got in the way, or that the website had a bug, or that the website implemented a different search algorithm, etc. If for whatever reason the search doesn't find existing inventory then the frontend has no way to know to ask to book it.