Best U.S. fare may be on a foreign website

It’s called Opodo.

In the same way that five large U.S. airlines -- American, Continental, Delta, Northwest and United -- created a jointly owned airfare-booking engine called Orbitz, nine large European carriers -- Aer Lingus, Air France, Alitalia, Austrian Airlines, British Airways, Finnair, Iberia, KLM and Lufthansa -- created a jointly owned airfare-booking engine called Opodo.

It’s sometimes possible to find a cheaper fare on www.opodo.com than on www.orbitz.com for a flight within the United States aboard a small U.S. airline. Why? It’s difficult to say. Sometimes one airfare-booking engine has the best fare, sometimes another. None of them, as far as I know, claims any longer to be totally unbiased. And though none actually hides a lower fare, they often make it hard -- but not impossible -- to find a cheap fare because of the prominence they give to the fares of preferred airlines.

It has become increasingly important for the cost-conscious flier to survey several airfare websites -- big and small sites, straightforward and comparison-type sites, and now U.S., European, Asian and Canadian sites that list U.S. flights.

Here are some you should check:

* www.itasoftware.com: This comprehensive site created by two graduate students at MIT purports to list every flight and price -- other than those for Southwest -- and it lists whether the flight is sold out. It is simply for informational purposes. After spotting an attractive fare, you must then go directly to the site of the airline whose flight and fare you want.

* www.sidestep.com: This is a comparison mechanism that you download. Thereafter, whenever you access an airfare-booking engine and choose a date and destination, SideStep pops up on the left-hand side of the screen to advise you of several other offers for the same date and destination. In effect, it surveys several of the airline- and non-airline-owned booking engines to give you other options.

* www.mobissimo.com: Currently in beta testing, this new service performs a function roughly similar to SideStep’s. It surveys and then advises you of the several fares for your date and destination available not only from numerous U.S. booking engines but those of Asia (www.zuji.com) and Europe (www.opodo.com), as well as Canada (www.destina.com) and France (www.anyway.com).

* www.anyway.com: The French booking engine accesses flights on U.S. carriers within the United States (prices are listed in euros), besides booking international fares. Anyway.com discoveries sometimes appear on the results of Mobissimo, even when domestic flights are searched.

* www.zuji.com: This is the chief Asian airfare-booking engine, popular in Australia, Hong Kong, Taiwan and Singapore, and is usable by residents of the United States. Users can pay for their tickets online with a credit card. I recently queried Zuji for a round-trip flight between New York and Los Angeles and was quoted $184 on Delta, far less than any U.S. booking engine offered for the same dates and destinations. (This fare may no longer be available.)

* www.destina.com: The major Canadian airfare-booking engine is operated from Montreal and is offered in English and French. Its price of $225 for a round-trip between New York and Los Angeles on either Delta or United was good but not as low as Zuji’s quote. (This fare may no longer be available.)

* www.opodo.com: And finally, this is the big, airline-owned European booking engine discussed above, whose quotes increasingly pop up on some of the comparison sites.

Scan them all, if you’re looking for the best fare.