More than a month after Malaysia Airlines passenger jet flight MH370 mysteriously disappeared, we find out how far technology can help investigators discover what happened.
As you read this, the expected 30-day battery-life of the Malaysia Airlines MH370 black box pinger will have expired, making it more difficult to locate the device in the massive southern Indian Ocean where the Boeing 777-200 is believed to have ended.
MH370 set off from Kuala Lumpur on 8 March, bound for Beijing carrying 239 people. The transponder, which provides ID and location data, stopped operating 40 minutes later, and the last voice contact was made as the plane left Malaysian airspace. The flight never reached Beijing, but what happened and why are matters that have been occupying investigators ever since.
Even if the black box is found, technical information from the flight data recorder (FDR) would not provide all the answers if technical problems were not the cause.
"Aviation experts would be able to pick up a lot of information from the FDR, but if there was deliberate action to turn off the transponders and Aircraft Communications Addressing & Reporting System (ACARS), then it will not be sufficient to reveal what really took place without the cockpit voice recorder (CVR)," said a high-level official of Malaysia's Department of Civil Aviation (DCA) in Putrajaya, Abdul Rahim.
The two transponders in the aircraft emit an identifying signal in response to an interrogating signal. Should one fail, the other is a back-up.
The 'black box' actually comprises separate voice and data recorders supplied by US-based Honeywell Aerospace. The CVR on MH370 will not reveal anything about the critical moment when the aircraft deviated from its original route. Only the last two hours of recording are maintained, as the CVR continuously records over itself. Normally it is the last section of a flight that determines the cause of an accident or crash.
In this case, the investigation team may never fully be able to solve this mystery, as they would not know what took place in the cockpit after MH370's final contact with air traffic control at the border of the Malaysia-Vietnam airspace, when the aircraft made an unexpected 180-degree left turn down to the west coast of the Malaysian Peninsula.
The B777-200 black box can withstand temperatures of up to 1,100°C and severe impact. It is designed to transmit a signal every second for 30 days.
Azmi Hassan, a geostrategist in Kuala Lumpur, says sonar technology will have to be used to find the black box if the aircraft's final resting place can be identified.
Azmi noted that only the US has such technology, whereby sunken objects can be detected to a depth of 6,000m in the ocean. "Sonar technology is able to zoom in on the type of object resting on the seabed and it is the only technology which can trace a black box that has stopped emitting signals," he pointed out.
The clock is ticking and the mystery deepens over what exactly caused the jetliner to cut communications 51 minutes into the flight. Several theories have been put forward – pilot suicide, rare freak electronic failure (RFEF), sabotage and hijacking.
"If it is RFEF, then it could possibly be the first time it has happened on a commercial flight," said Azmi.
What is alarming is that the Royal Malaysian Air Force (RMAF) failed to act when it detected an aircraft on the military radar on 8 March flying in Malaysian airspace.
High-level RMAF officials were only willing to say it was assumed it was a Malaysian aircraft, hence there was no follow-up. When asked how they could have taken that risk, they declined to comment.
No action has yet been taken against the officers who were on duty at that time, neither has an investigation been initiated.
Acting Transport Minister Hishammuddin Hussein, who also holds the Defence portfolio, has said his priority at the moment is to search for MH370 and get to the root of the tragedy. "That is my and everyone else's main concern, as we need answers," Hishammuddin said.
Initial efforts focused on looking for floating debris of MH370, which was expected to be a far easier task than locating and recovering the recorders.
Subsequent analysis of satellite images and data, notably the work by Inmarsat and the UK Air Accident Investigation Branch, has identified the most likely area as the southern Indian Ocean west of Perth, Australia, from where the search effort is now being led.
Twenty six nations including the US, Australia, Japan, New Zealand and Korea have joined the search for MH370. The already tedious task has been further challenged by violent storms and cold weather.
At the time of writing, an Australian ship towing a US Navy pinger locator has detected signals at the correct frequency for a flight recorder. This should help narrow the search area so an autonomous underwater vessel can examine the seabed.
"I believe we are searching in the right area," said Air Chief Marshal Angus Houston, who heads the joint agency co-ordinating the search. "But we'need to visually identify aircraft wreckage before we can confirm with certainty that this is the final resting place of MH370."
Comparisons have been made with the case of Air France AF447, which was on a flight from Rio Janeiro to Paris when it crashed into the Atlantic Ocean on 1 June 2009. That wreckage was spotted six days later, but even so it took two years to locate and recover the black box deep in the ocean in May 2011.
Two issues remain hanging over MH370. One concerns inconsistent information regarding the number of passengers who checked-in for the flight but did not board.
On 9 March DCA director general Azharuddin Abdul Rahman said five did not board and their baggage was offloaded in line with safety requirements.
Three days later Malaysia Airlines CEO Ahmad Jauhari Yahya indicated that four passengers did not show up for the flight. "Four passengers who were on standby for MH370 were then checked-in," Ahmad said.
Then on 14 March inspector general of police Khalid Abu Bakar said there were none on standby and all 227 passengers who were booked, boarded.
Ahmad's statement was rather surprising as the booking engine of an airline will not issue the travel itinerary if a flight segment is not confirmed. The flight was also not fully-booked, so the question of passengers on standby did not arise.
Airlines stopped issuing paper tickets on 1 June 2010 and started issuing the travel itinerary electronically the same day.
"Conflicting statements issued by the various officials will make it more difficult," said a member of a foreign investigation team who declined to be named.
The second issue, how two Iranian passengers with stolen passports were cleared by immigration officers at Kuala Lumpur International Airport (KLIA), remains unresolved. The two travelled from Bangkok to KL on 28 February with their original Iranian documents then switched to Austrian and Italian passports. Both these passports had been reported stolen in Phuket, Thailand, in August 2012 and 2013 respectively. The Iranians were reported to have bought them for US$2,600 each from a Thai syndicate.
Immigration Director General Aloyah Mamat claimed that biometric screening was used to check the validity and authenticity of the Iranian passports at the point of departure in KLIA. When told that DCA had confirmed the two Iranians had used the stolen passports to clear immigration, Aloyah declined to comment.
Malaysia is a hub for human trafficking. Over the past eight months several Malaysian immigration officials have been prosecuted and convicted for taking bribes to allow illegal immigrants into the country.
Questions of lax security at KLIA have also been raised, which Immigration and Malaysia Airports Holdings Berhad (MAHB) officials have been quick to deny. MAHB operates and manages 22 airports across the country.
Malaysian Airlines has had an excellent safety record in its 42 years of flying, but the loss of MH370 has revived memories of one previous disaster that has never been fully explained.
On 4 December 1977 flight MH653, a Boeing 737-200, was on a 40-minute domestic flight from Penang to Kuala Lumpur but was hijacked as it prepared to land and diverted in the direction of Singapore. Both pilots were shot at point blank range by the hijacker, and the aircraft eventually crashed into a mangrove swamp. All 93 passengers and seven crew perished. Investigations revealed that lax security at Penang International Airport had enabled the hijacker to board the flight with a revolver.
Additional material by Lorna Sharpe