BERLIN/FRANKFURT Within 40 minutes of Germanwings flight 4U9525 crashing in the Alps in March French accident investigators from the BEA authority were on the phone to plane tracking website Flightradar24.
"BEA called us and we of course passed the information over to them right away," the website operator's chief executive Fredrik Lindahl said.
The data showed the Lufthansa-owned jet making a steady descent and not veering off course, leading to early speculation among experts of pilot suicide as a possible cause, a theory confirmed over the next days and weeks by readings from the plane's voice and cockpit data recorders.
"It doesn't make any difference to investigation by the authorities but because the media have access to Flightradar24 detail it puts pressure on them to confirm or deny what Flightradar24 shows at a time when they are very busy trying to validate what they think they know," said David Learmount, a British aviation industry journalist and veteran commentator on airline safety issues.
Flightradar24's website and apps show live data on air traffic around the world received mainly via its network of over 7,000 receivers that pick up positional information from a plane's ADS-B transponders.
The receivers are largely operated by volunteers, who in exchange receive a premium subscription, and the company said it sends out for free around 50 receivers a week, each costing around 500 euros ($570) to manufacture and post.
"We're very lucky that people find this all so fascinating," Lindahl told Reuters.
From a two-man start-up in Sweden, Flightradar24 has now overtaken other flight tracking services such as FlightAware and Flightstats in terms of popularity and says airlines and airports are also turning to using its services.
For example both Dublin Airport and European budget carrier easyJet have signed up with Flightradar24 to provide tracking information services for their flights.
Flightradar24 also sells data to two of the world's largest 10 airlines and Lindahl expects more will follow, though with a full-time staff of just 20, he said it is tough to meet demands for customized services.
The idea of a site to track planes started as an afterthought, when back in 2006 Swedes Mikael Robertsson and Olov Lindberg were looking for a new way to boost traffic to their travel price comparison website.
As aviation fans, they hit on the idea of installing ADS-B receivers on the roofs of their homes to track planes over Stockholm. Tracking planes quickly proved far more popular than comparing prices and so they decided to focus on Flightradar24.
The service was not entirely new, with U.S.-based FlightAware which started in 2005 saying it was the first to offer free flight tracking services.
But Lindahl said Flightradar24, which has over 1 million regular users a day, now has by far the world's largest network of receivers and search data shows it gets twice as many searches on Google as FlightAware.
In order to boost coverage further, Flightradar24 has sent out over 100 receivers to Africa alone this year and is also in talks to put receivers on buoys at sea, although Lindahl expects this to take some time.
"It's about building up our network of receivers and that's where we're putting our focus," he said.
And funding does not appear to be a problem. Lindahl says Flightradar24 made an operating profit in its last financial year of 20 million Swedish crowns ($2.4 million) on revenue of 43 million and has caught the eye of venture capital investors.
But he is not interested at present.
"There may come a situation when we need the funding, who knows, but it seems unlikely at this time," Lindahl said.
($1 = 8.2974 Swedish crowns)
($1 = 0.8814 euros)
(Editing by Greg Mahlich)