Steve Landells
Flight Safety Specialist

With the MH370 search being recently suspended, questions have resurfaced about how possible it is to ‘lose’ an aircraft. Despite today’s technology, it can take so long to recover the part of the aircraft equipment which holds all the vital information – the black boxes. Although aircraft disappearances aren’t common, the examples below show why we should be developing and implementing solutions to prevent it taking so long for data to be recovered when an aircraft disaster occurs.

Air France flight 447

The A330 flying from Rio to Paris in June 2009 entered an aerodynamic stall and crashed in the Atlantic Ocean, killing all 228 passengers, air crew and cabin crew on board. Within five days, the major wreckage and two bodies were recovered, but investigations were hampered because the aircraft’s black boxes weren’t recovered until nearly two years later. In addition to the usual GPS data transmitted from the aircraft, there was a series of messages sent to maintenance workers on the ground immediately before it disappeared. However, they presented an incomplete picture. The majority of the vital recordings were stored on the black box, significantly slowing down the investigation.

The black box was fitted with a water-activated acoustic underwater locator beacon (ULB), with a battery life of 30 days. This meant that as time elapsed, the possibility of finding the black box diminished.

The memory unit of the flight data recorder was recovered on 1st May 2011, and the cockpit voice recorder a day later. By 15th May all data from the flight data recorder and the cockpit voice recorder was downloaded.

Malaysia Airlines flight MH370

The most recent and extreme case of failure to locate an aircraft’s black box is flight MH370, which disappeared on 8th March 2014. After nearly three years, the search was called off last week. The multinational search for the aircraft and its data recorders was the largest and most expensive in aviation history. From October 2014 until January 2017, a search of 120,000km2 recovered no evidence, prompting speculation about the fate of the aircraft.

Flight MH370 brought more attention to the limitations of black boxes, namely the limited data storage and finite battery life and signal distance of the ULBs attached to them. Even if the black boxes are found, the cockpit voice recorder is currently only capable of holding two hours of data. Usually, the data from the last two hours of the flight is sufficient in determining the cause of the accident. However, with MH370, this may not be the case.

What’s being done now?

As a result, the International Civil Aviation Organization (ICAO) has adopted new protocols for aircraft travelling over open waters.

In March 2016, ICAO adopted several new requirements for black box data storage. For aircraft manufactured after 2020, cockpit voice recorders will be required to record at least 25 hours of data, so all phases of a flight are recorded.


A call to increase ULB battery life, after initially being made in 2009 after the AF447 disaster, was finally recommended by ICAO in 2014 to be implemented in 2018. The European Aviation Standards Agency (EASA) have also stated that the battery life of ULBs must be increased from 30 to 90 days.

The furthest distance a ULB’s signal can be detected from is 2,000 - 3,000 metres (4,500 in favourable conditions), encouraging the implementation of new designs to enable the recovery of flight recorders and their information before they sink below water, as well as new technologies enabling data streaming to the ground.

The US National Transportation Safety Board has also issued eight recommendations citing AF447 and MH370, including crash-protected cockpit image recorders and tamper-resistant flight recorders and transponders.

What is BALPA calling for?

We don’t believe it should be possible, in this day and age, to lose an aircraft. Ideally we’d like to see more technical aircraft data being transmitted to a ‘virtual black box’ when a flight gets into problems so the site and possible cause of a crash can be identified sooner. Unfortunately we regularly see data leaked to the press very soon after an accident and this only leads to increased speculation and more distress for the families of those involved. So until the security of data can be assured, BALPA believes that only very limited data should be transmitted automatically. It is for this reason that BALPA is not in favour of the introduction of cockpit image recorders, especially those which capture images from which the crew can be identified.

If and when the security of data issues have been addressed aircraft should be modified to send a burst of vital technical data from the cockpit as soon as it behaves outside normal flight patterns. This information would be saved virtually, with strict access controls, and used to locate the aircraft and provide an early indication of what happened, pending a full investigation using the cockpit voice recorder and flight data recorder once retrieved from the aircraft.

Accidents are very rare, so a forensic investigation into every aspect of every crash is essential, and black boxes sinking to the bottom of the sea with the airframe, or being destroyed by a post-crash fire only delays potentially life-saving recommendations. One area that warrants further investigation is that of “deployable recorders” that are ejected from the aircraft shortly before impact.

We encourage airlines and manufacturers, where appropriate security measures are in place, to introduce normal and distress tracking and flight data recovery solutions as soon as possible on all their aircraft.

We’re now seeing some good initiatives being taken by ICAO and other worldwide organisations. While we welcome these proposed changes, they aren’t going to prevent disasters like this happening in the future. We still need to ensure our priority is preventing accidents and that we don’t introduce new hazards while preventing others. For example, if recorders were to be made ‘tamperproof’, is having electrical equipment on board that pilots cannot isolate sensible? And perhaps we should ask ourselves if any solution involving introducing extra lithium batteries is a good idea. We’re moving in the right direction, but we still have far to go.

Posted on 25 January 2017

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