EVERYONE knows airfare prices fluctuate. If you buy at the right time, you could pay a lot less than other people on the same flight. If you miss your window, you can end up paying a lot more. That's one reason why Microsoft bought Farecast: the latter's price prediction technology made the former's Bing Travel site more attractive. But even Bing Travel only offers customers a general sense of where fares might be headed. Yapta, a site that tracks ticket prices, is trying a different tack—allowing potential travellers to track flights to their dream destinations and buy when the price seems low.

Anyway, travel blog godfather Chris Elliott recently spoke to the folks at Yapta about their price tracking. It turns out they've learned some pretty remarkable facts:

The most volatile airline ticket prices in America are between Atlanta and Las Vegas, a new survey by Yapta has found. Fares between those cities changed an astonishing 2,472,916 times since the beginning of the year. That's roughly once every six seconds. [...] Here are the top 10 domestic city pairs with the most volatile airfare prices this year. This data is across all flights (one way, round trip, multi-city) and seat classes. 1. Atlanta (ATL) to Las Vegas (LAS) – 2,472,916 price changes

2. New York (JFK) to Las Vegas (LAS) – 2,412,759 price changes

3. New Jersey (EWR) to Las Vegas (LAS) – 2,377,668 price changes

4. Chicago (ORD) to Las Vegas (LAS) – 2,215,994 price changes

5. New York (JFK) to San Francisco (SFO) – 1,959,873 price changes

6. San Francisco (SFO) to New York (JFK) – 1,862,270 price changes

7. Los Angeles (LAX) to Honolulu (HNL) – 1,740,380 price changes

8. New Jersey (EWR) to Orlando (MCO) – 1,725,727 price changes

9. Los Angeles (LAX) to New York (JFK) – 1,641,397 price changes

10. Boston (BOS) to Chicago (ORD) – 1,490,271 price changes

Mr Elliott's full post has a lot more to offer, including the 10 American city pairs with the least volatile prices (Hello Clarksberg, West Virginia to Portland, Maine!) and more explanation from his Yapta contact. But Mr Elliott also goes on to ask an important question: "Why is this allowed?... [I]t's hard to think of any other consumer product with such volatile prices." Since Mr Elliott specifically asks for input from "all the free marketers out there," I think Gulliver is required to respond.

Thankfully, this is an easy one. The prices between the top city pairs change a lot because there's a lot of competition on those routes. Competition is good—it keeps prices low for travellers. Why shouldn't airlines be allowed to change their ticket prices frequently? (Actually, as commenter JasonZ points out at Mr Elliott's site, 2.5 million changes isn't as many as it seems.)

There's more to this. I'd much rather buy tickets for a route with volatile prices than buy them for a route with a stable price. The volatile city pairs are a lot cheaper to travel between. The reason the prices are so stable between Clarksberg, West Virginia and Portland, Maine is that there's no competitive pressure on that route. If there was more competition on that route, prices would fluctuate more—but tickets would probably be cheaper. Anyway, there's a good debate in Mr Elliott's comment section. Check it out, then come back and tell us what you think.

(h/t The Consumerist)