On Expedia, I found a good flight deal in the list of search results, but when I click it, the next page says:

Price change

Ticket prices changed from $ to $. Because prices change often, we recommend booking now to lock in this price.

I went back to search again, and found that the good deal had disappeared from the list of search results. However, after an hour, the good deal reappeared in the search result list, but disappeared when I clicked on it. The airline's website does not have the good deal in the list of search results, as far as I have tried searching.

So, what is going on between Expedia and the airline? Should I keep searching from time to time, hoping that I can catch the deal? The flight is only three days away.

Screenshot: New York to Guangzhou Feb 1. Choose departing flight > Review your trip. Multiple options, Wed Feb 1 for $889 is selected. Details of the selected option are show below that: 6:00pm - 9:00 pm (+2), New York (JFK) to Guangzhou (CAN), 38h 0m (1 stop), 17h 55m in KWI, Kuwait Airways, $889 Screenshot: A warning reading "Price Change. Ticket Prices changed from $888.01 to $1,013.10. Because prices change often, we recommend booking now to lock in this price." Below that the details of the selected flight: New York to Guangzhou, 6:00pm - 9:00 pm (38h 0m, 1 stop), Kuwait Airways - Wed Feb 1, $1,014. Check out button visible.

  • 15
    Beeing a sceptic I believe that this is part of the sales strategy. The point is to make the buyer act, not wait and think. Once the buy is finished you are comitted.
    – ghellquist
    Commented Jan 30, 2023 at 8:54
  • 4
    "because we can!"
    – fraxinus
    Commented Jan 30, 2023 at 13:49
  • 3
    If you revisit the site in private browsing mode... You'll likely see the price goes back down Commented Jan 31, 2023 at 9:45
  • @ScottishTapWater almost always a myth.
    – Mark Mayo
    Commented Feb 3, 2023 at 1:11
  • 2
    @MarkMayo - Having worked as a software engineer in one of these companies, I can promise you, it's not. Private browsing alone might not do it, there are other heuristics that are used to identify repeat visitors, but dynamic pricing definitely tries to raise prices on subsequent visits to incentivise purchases. Suffice to say, I didn't remain at that company long after I found this out, it's immorral, but it's no myth Commented Feb 3, 2023 at 23:03

3 Answers 3


I run a flight search website (Beat That Flight) in Australia that aggregates sites like this. It's one of the biggest problems.

Say you're flying from Chicago to Los Angeles. There are literally thousands of possible routes (you might decide to fly via Albuquerque for some reason) and each route has multiple airlines, and times. All these flights often have different classes (Economy, business) and even within Economy, multiple pricing buckets.

All these are changing regularly, as people buy tickets, airlines price a lot based on demand, deals etc.

All this data needs to flow into various GDSs, across networks and have all the travel agency etc discounts added and updated. Constantly.

There's a white paper here that explains in more detail.

From the whitepaper:

Just for San Francisco to Boston, arriving the same day, there are close to 30,000 flight combinations, more flying from east to west (because of the longer day) or if one considers neighboring airports. Most of these paths are of length 2 or 3 (the ten or so 6-hour non-stops don't visually register on the chart to the right). For a traveler willing to arrive the next day the number of possibilities more than squares, to more than 1 billion one-way paths. And that’s for two airports that are relatively close. Considering international airport pairs where the shortest route may be 5 or 6 flights there may be more than 1015 options within a small factor of the optimal

Short version - basically updating in real time is nearly impossible. Sites like expedia often cache prices, and update when there's a search for a particular date/time, because there's so many combinations there's little value in say, updating El Calafate, Argentina to Dushanbe, Tajikistan in real time when you could be putting more resources into updating New York to Los Angeles - a more commonly searched route.

As a result, it's not uncommon that the price you see has changed in the background. One of the tickets in a particular bucket may have just been snapped up elsewhere.

You can try, and indeed sometimes it's a routing update that fluctuates and it may come back. But three days out, that's less likely.

Hope that made sense.

  • 2
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    – JonathanReez
    Commented Jan 30, 2023 at 16:31

No one can be certain without access to Expedia's logs, but it's likely the lower price was previously available, but has sold out. The answer by @Mark Mayo gives a good summary of the general technology behind these sites. I've never worked for Expedia, but I have worked on similar systems.

For the specific behaviour you have seen, this could have been caused by Expedia getting their data from multiple sources.

  1. A bulk source, that gives them prices and availability for thousands of flights at once. This will be imported to their database on a regular basis (e.g. once per day). This is sometimes called a flat file, although that refers to a specific type of technology and other bulk sources exist.
  2. A live source, that looks at a single flight.

First all the flight data is loaded from the bulk source into the Expedia cache, which is then used to show you your initial search results. When you select a single flight, it goes and checks the live source to see if the price is the same. If there is a price difference, it displays the "Price change" message to the user and also updates the cache for this specific flight with the new live price. This is why if you run the search again immediately it will now show the higher price in the list of search results.

Some time later, they will run a fresh import from the bulk source. This data is now considered newer and more accurate than the live price retrieved for your individual search, and therefore the bulk price is added back to the cache.

In an ideal world, the bulk source has been updated, and it's the higher price that ends up in the cache and the search results will correctly show the higher price and no "Price change" message. However, if the bulk source still has the lower price, then it will get added back to the cache and show up again in the search results. This could happen for a few reasons, including:

  • The process to import the bulk data can be slow, especially as the data often needs to flow between multiple systems run by different companies. That price may have sold out between the start of importing the bulk data, and the end.
  • The code that calculates the bulk and live prices is different. A bug in either can cause them to disagree about whether a flight can be sold at a particular price. e.g. maybe the $889 is a non-refundable fare but you've asked for refundable fares. A bug in the bulk import could have meant the $889 fare was classified as a refundable fare in the cache.

Expedia will have staff looking into these prices differences and working to fix whatever is causing them, but it's a difficult problem to solve.

  • 2
    Multiply this by the fact that the backends are stateless with respect to the user session and don't all get the feeds at the exact same instant. You could easily be hitting different backend machines behind the load balancer. And the feeds are coming in all the time and at wildly different rates. And there are upwards of 1000 backend machines ... (this is for quotes, when it is time to purchase the rate is confirmed with the provider in real-time)
    – davidbak
    Commented Jan 30, 2023 at 21:21
  • @davidbak In English? Commented Jan 31, 2023 at 22:59
  • @AzorAhai-him- Stateless: They don't remember anything about your last interaction. || .. not all the feeds ...: They have MANY sources and only some are used every time you ask. The ones used may and probably do vary. || Different sites quote different rates. || Quotes are "on the fly" based on stored data that may be old in moments. When you BUY they get the current real rate. Commented Feb 1, 2023 at 2:23
  • 1
    @AzorAhai-him- Backends: Expedia is not run on one computer (server). They will have a set of servers, and you'll get randomly allocated one when you visit the site. Each server may have its own copy of the list of flights, and the copy on one server may be older than the copy on another.
    – thelem
    Commented Feb 1, 2023 at 11:20

What your noticing is a common practice known as dynamic pricing - And what dynamic pricing is, the ticket price can change depending on a couple of factors; 1. Number of people searching and 2. The timeframe they're searching for.

So, by searching multiple times, you'll see a higher price each time because now, more people have seen your search and decided to buy tickets at that rate.

A good rule of thumb, in order to avoid this, you'll want to book your flights on the very first search you do OR use an incognito window, so airlines won't be able to track your searches.

Hope this helps!

  • 2
    The incognito window thing is almost always nonsense, flight search sites have run scripts hundreds of times comparing the two and found no difference. However some sites have offered you higher priced hotels based on your computer type... wsj.com/articles/SB10001424052702304458604577488822667325882
    – Mark Mayo
    Commented Jan 30, 2023 at 21:40
  • I disagree it’s nonsense. I know for a fact that Agoda will show me higher prices (plus “discount”) as a logged in user. And that’s just one vendor. You can’t say that “it almost never applies” because there are a million vendors with their own logic which you do not know. It’s always worth a check if you’re 5 minutes away from confirming.
    – fregante
    Commented Feb 1, 2023 at 20:45
  • @fregante by all means, try. As I said and even gave an example, some do perform dark patterns like this. But I spend....far too much time looking for flight deals every day and still haven't come across a repeatable example of this for flights. Off to check Agoda now tho :P
    – Mark Mayo
    Commented Feb 3, 2023 at 1:13
  • ok I'm back. Signed in user, searched CHC to SYD, Mar 25, NZ$372.82. Opened incognito, checked, exact same price.
    – Mark Mayo
    Commented Feb 3, 2023 at 1:15
  • Proof: i.sstatic.net/7LGRy.png The fun part is that a Google search user gets a lower price AND a refundable booking. YMMV
    – fregante
    Commented Feb 6, 2023 at 10:02

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