Google doesn't really talk about how well its Flights metasearch engine is shaping up against its powerful competitors - but external data providers can help shine a light.
One of the original challenges that many thought the search giant would have was in its ability (or not) to lure loyal users away from the likes of Kayak in the US and Skyscanner in Europe.
Google Flights is now well over half a decade old (gulp!), launched initially in the summer of 2011 once regulators in the U.S. gave it clearance to proceed following its $700 million acquisition of ITA Software the year before.
Any initial praise in the early days (even from its competitors) was directed towards the speed in which it was able to return results - hardly a surprise given the importance that Google has always placed on how quickly its users could find what they're looking for.
This was a direct result of using the QPX system developed by ITA Software (it was also used by Kayak, before it switched to Amadeus's MetaPricer product a few years after the Google acquisition) - yet the breadth of airline coverage was an issue for a number of years.
Once this was ramped up, circa 2012-2013, attention turned back to how would Google push the product in front of users.
Settling in and pushing on
Google Flights is now a core part of the airfare search experience on Google, with increasing levels of functionality being added in recent years.
As a result, Google is now a serious player in flight search (as the likes of Kayak feared at the time of the acquisition, leading it and a number of other brands to join the FairSearch lobbying group).
Two sets of data have illustrated its growing influence on the metasearch ecosystem and adoption rates by users.
Firstly, analytics service Jumpshot found last year that Google Flights was growing at a much higher rate than it had been in previous years.
There was a 27% jump in unique visitors to Google Flights in the first quarter of 2017 compared to 2016, with a 17% increase in the second quarter.
Growth of the tool had been fairly flat during 2015 and 2016, according to Jumpshot.
The increase in user numbers led to a significant increase in referral to its airline partners at the same, with a massive 69% climb to the top nine U.S. airline sites.
Carriers such as American Airlines, United and Delta, for example, by the middle of last year, were getting three times as much traffic from Google Flights compared to just two years before.
Conversion rates (the most important bit in the metasearch process) are also said to be good, with the average in the region of 25% by the second quarter of last year - the exception being Southwest with a lowly 8%.
Here and now
Jumpshot says airlines that "don't make an effort to put their every piece of information on the tool will suffer in gaining conversions from Google Flights" - a signal that most carriers will eventually switch on a full feed of fares to Google if they see themselves falling behind others.
Data released this week by SimilarWeb paints a similar picture of the position of Google Flights as a contender in flight metasearch, but in the context of comparing it to Kayak.
Two of the three airlines the company analysed had Google Flights either performing the same or better than Kayak, when looking at the growth in referrals between February 2017 and January 2018.
United, for example, had 29% increase in referrals from Google Flights and 30% for Kayak.
FlyFrontier, in contrast, saw a 35% increase in referrals over the same period, with 26% for Kayak.
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