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Two aircraft, one of which belonged to Air India, were about 25 km away from the Malaysian airlines flight MH17 when it 'disappeared' over Ukraine on Thursday night, said the aircraft tracking site Flightradar24.com, but the Indian Civil Aviation Ministry has since asserted that "there was no Air India flight near the ill-fated Malaysian plane."
Both Air India flight 113 (operating between Birmingham and Delhi) and a Singapore airlines flight were about 25 km away from the Malaysian plane when it went off the radar, said >a tweet from Flightradar24, just a couple of hours after the mishap occurred.
Aircraft tracking sites like >Flightradar24 access data gathered by a network of aircraft spotters which then is used to show the movement of planes on a map. The site says it relies on a largely volunteer-driven aircraft spotting network for data, which is fed into servers to show the position of aircraft. A transponder on a plane transmits a signal which is picked up by a receiver on the network. One way of doing it is based on automatic dependent surveillance-broadcast (ADS-B) technology. Some planes have an older kind of transponder called Mode-S, in which case time difference in receiving the signal can be used calculate the location. Data from Federal Aviation Administration in the United States is also used. A large network of receivers in different parts of the world provide data that drives the service.
From a Flightradar24 screenshot; the positions of the two planes have been highlighted.
"About 99 per cent of Europe is covered with ADS-B receivers. There is also good ADS-B coverage in USA, Canada, Caribbean, Brazil, Russia, Middle East, India, Japan, Thailand, Malaysia, Indonesia, Australia and New Zealand. In other parts of the world the ADS-B coverage varies."
How accurate or reliable is this kind of information? It is dependent of many parameters including aircraft type, aircraft transponder type, aircraft altitude and terrain, the website says. Besides, the service uses airline and airport schedule databases to match the flight number with the data received, which could be liable to errors.
Tracking also becomes difficult when the planes fly over oceans.
The need for having a standards-based and reliable system of real time flight data monitoring came into sharp focus when another Malaysian airlines flight MH370 disappeared on March 8, 2014 after it took off from Kuala Lumpur enroute Beijing. The missing place is yet to be traced.
Though some technologies for real time flight data monitoring are already available, or will be soon, the global aviation sector was keen on also using existing technologies, said an outcome document issued after an expert meeting that the International Telecommunication Union (ITU) had called in May in Kuala Lumpur, following the disappearance of MH370.
Technology developers, service providers, airline companies and international aviation bodies also needed to agree on standards, policies and regulations and harmonized spectrum to pave the way for interoperability on a global scale and cost-optimisation.
If flight data was stored on standards-based aviation clouds interested parties could apply state-of-the-art data analytics and data mining techniques in real-time for the benefit of passengers and better operational efficiency, some participants had said at the meeting.
Meanwhile, a special meeting of the International Civil Aviation Organisation that dealt with global flight tracking in Montreal in May had said that "global tracking of airline flights will be pursued as a matter of priority to provide early notice of and response to abnormal flight behaviour" and that a draft concept of operations on flight tracking would be developed in the near term.
