I alluded to these in an earlier column; here are some more detailed suggestions. The most useful airfare alert systems are the ones that monitor specific trips you have in mind and let you know when fares drop on routes you select. Among the better choices:
Independently of Airfarewatchdog, SmarterTravel provides daily or weekly email bulletins covering hotels, car rentals and packages, as well as airfare deals. You can also sign up for daily to weekly Departure City Fare Alerts from your home airport and for periodic City to City Route Alerts on individual trips. Enroll on the home page. FareCompare offers similar reports.
Some big online travel agencies (OTAs) and metasearch engines provide similar periodic airfare sale and fare change bulletins. Many also offer the same information through some combination of Facebook and Twitter linkages.
Many domestic and international airlines offer some combination of email, Facebook and Twitter deal updates; many also provide apps for smart mobile devices. If Southwest is in your orbit, install its "Ding" feature that automatically sends fare change information to your computer via RSS or the corresponding iPhone app. Sign up for as many other lines as you might want to travel -- if you don't mind a big jump in your email volume.
No matter which bulletins you choose, keep in mind the "usual suspect" strategies for minimizing airfares:
-- To/from multi-airport cities, check all the airports.
-- To/from smaller cities, check nearby larger cities where fares may be more competitive.
-- If you're flexible, look several days before/after your preferred trips for better deals. Many OTA and airline websites allow for flexible date searches.
-- Don't forget about traditional travel agents, who can track deals for you.
For the most part, these sources are most useful for tracking airfares before you buy. Yapta.com, among others, also features notification of a price drop on a ticket you've already purchased. This may or may not be useful; on most lines, a fare would have to drop $200 to $300 before you could benefit by re-ticketing, but it might be useful on Southwest, which doesn't impost change fees.
One other caution: As far as I can tell, none of the bulletins I've described deals with anything other than finding the lowest available coach/economy fares. To date, I know of no source that tracks premium economy, business and first-class fares in a similar way.
(Send e-mail to Ed Perkins at eperkins(at)mind.net. Perkins' new book for small business and independent professionals, "Business Travel When It's Your Money," is now available through http://www.mybusinesstravel.com or http://www.amazon.com)
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