Originally Posted by Globaliser

If an airline is playing married sector games, then ITA won't always produce reliable results because of the way that it works. AIUI, the Matrix tool does not look up availability in real time for the requested itinerary but uses cached sector-by-sector availability results. My impression is that it will therefore construct and price itineraries for which there is availability when asked for sector by sector, but if a real-time search results in the airline denying inventory in the required class when the entire itinerary is asked for because of married sector games, then ITA will not detect that.

EF is a better guide to true real-time availability in these situations, because it does make a real-time request of the airline for the requested itinerary.

This is one of the reasons that someone who values these travel tools should always be prepared to use them in combination.