WATCH: There are more questions than answers following the Malaysian military’s denial about a possible location of the missing plane.
KUALA LUMPUR, Malaysia – The missing Malaysian jetliner may have attempted to turn back before it vanished from radar, but there is no evidence it reached the Strait of Malacca, the country’s air force chief said Wednesday, denying reported remarks he said otherwise.
The statement suggested continued confusion over where the Boeing 777 might have ended up, more than four days after it disappeared en route to Beijing from Kuala Lumpur with 239 people on board.
Air force chief Gen. Rodzali Daud was quoted as saying in local media report Tuesday that the military had radar data showing the plane had turned back from its original course, crossed the country and made it to the Strait of Malacca to the west of Malaysia. The Associated Press contacted a high-level military official, who confirmed the remarks.
In a statement, Daud denied saying the remarks, and referred to a statement he made March 9 in which he said the air force has “not ruled out the possibility of an air turn back” and said search and rescue efforts had been expanded in this regard.
Authorities began their search for the missing aircraft at the position it was last reported to be over the sea between Malaysia and Vietnam. But they have also said search operations were ongoing in the Malacca strait.
With no debris found yet, authorities have not ruled out any possible cause, including mechanical failure, pilot error, sabotage or terrorism.
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Tracking planes
The plane’s transponder could have either been shut off or an electrical malfunction may have caused it to stop transmitting. The transponder sends signals to receivers, including radar used by air traffic controllers and a malfunction or deliberate shut-off would have made it disappear from two kinds of tracking systems.
Primary radar is the traditional radar that scans the airspace, often used by military. Secondary radar, is most commonly used by air traffic controllers. When this type of radar scans the airspace and makes contact with an airplane, a signal is then sent back from a transponder, giving not only the plane’s location, but data like altitude and speed.
READ MORE: Malaysia Airlines flight MH370: how can a jet just disappear?
But within the last decade, a new form of tracking has gained popularity: Automatic dependent surveillance-broadcast, or ADS-B. This type of tracking, like our cars, uses GPS. But with ADS-B technology, the aircraft takes that data-locating information and sends out a radio signal.
“You don’t need this rotating radar,” Michael Robertsson, co-founder of FlightRadar24 told Global News. “The aircraft is transmitting the information by radio from the aircraft, so you just need a small, simple radio receiver to pick up the signal from the aircraft.”
Robertsson estimates that about 60 per cent of the global fleet is using ADS-B, but only a few countries have mandated its use. In 2013, Australia became the first country to do so.
But a plane’s transponder can be turned off, which would make it untrackable by ADS-B and secondary radar. However, it would still be visible on primary radar, though it wouldn’t provide information like altitude and speed.
“In this case, it looks like this is what happened — they turned the transponder off,” said Robertsson. “So it disappeared from our map; they disappeared from air traffic control, but they were still visible on military radar.”
READ MORE: Malaysian military says missing jet changed course
In the case of MH370, FlightRadar’s own receivers were tracking the Boeing 777 when it disappeared.
ADS-B does have some limitations. One being that it needs ground-based radar. And that only extends to about 300 to 400 km range. Over wide-open places, such as the Atlantic Ocean, there are no ADS-B receivers to get the data to track the plane. There are plans for satellites in low-Earth orbit to basically fill in the missing information. NAV Canada has partnered with U.S.-based Aieron to essentially fill in the gaps of data by using satellites in low-earth orbit.
Interpol releases image of 2 Iranians on missing plane
Interpol says it seems unlikely that two men who boarded the missing Malaysian Airlines plane with stolen passports were terrorists.
An official says it appears the two Iranian men — who used their own passports to get to Malaysia before switching documents for the flight to Beijing — were seeking asylum in Europe.
Airline probing report 2 visited cockpit in 2011
Malaysia Airlines says it is investigating an Australia television report that the co-pilot on its missing flight had invited two women to stay in the cockpit for the duration of a flight two years ago.
The airline said late Tuesday it wouldn’t comment about the report until its investigation into it is complete.
Roos said she and her friend were allowed to stay in the cockpit during the entire one-hour flight in December 2011 from Phuket, Thailand, to Kuala Lumpur. She said the arrangement did not seem unusual to the plane’s crew.
Flight tracking technology
ADS-B tracking for air traffic has not been mandated in Canada, though it is used. NAV Canada also uses ADS-b in the north where ground-based coverage is limited, for example in the case of uninhabited locations or over the Labrador Sea. In the United States, the Federal Aviation Authority is mandating that all aircraft be tracked using ADS-B technology by January 1, 2020.
Still, as more and more planes are equipped with this ADS-B technology, they can easily be tracked by anyone with a radio. In fact, this can be — and is — done by ordinary people.
Several flight tracking websites, including FlightRadar, use data collected from people. These people, typically avid plane watchers, have antennas, a receiver capable of receiving ADS-B signals, and software to decode the signals. There are also other software applications that allow people to plot and decode the signals without having to feed data to these sites, such as PlanePlotter.
When flight MH370 disappeared, it was being tracked by FlightRadar’s own ground-based receiver. FlightRadar has a total of 3200 ground-based receivers — 1300 of their own, and 1900 from private citizens. And it seems that more and more people are anxious to collect data Their receivers have grown from 800 last year.
The search for the MH370 continues, and after two days with many questions still left unanswered and several more are being raised.
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