What is a black box and how do you find one? Searching for the last remains of flight MH370

These indestructible instruments have been part of air travel for decades, but what exactly do they record and why are they so hard to find?

Time is running out for the search teams hunting for the black boxes from missing Malaysia Airlines flight MH370.

These devices (known as ‘crash-survivable memory units’ in the official jargon) could hold vital information, but the batteries powering their locator beacons only lasts for around thirty days.

Once these die the black boxes will lay silent on the bottom of the ocean floor, making their discovery even more unlikely. But what exactly are search teams looking for and just what do they hope to find?

What is a black box?

Black boxes are specialized devices designed to record the final moments of a flight and survive the extreme heat and pressures of a crash. There are usually two black boxes located in the rear of the plane (usually the last point of impact) each recording a streams of information: the first, the Cockpit Voice Recorder (CVR) stores the last two hours of conversation in the cockpit, and the second,  the Flight Data Recorder (FDR) keeps a larger set of data outlining the altitude, airspeed and direction of the flight for the last 25 hours. Modern recorders include much more data – about everything from fuel levels to the position of wing flaps.

The two black boxes retrieved from the Afriqiyah Airways Airbus jet that crahsed in Libya in 2010.

What are they made out of?

The ‘crash survivable memory unit’ is actually a steel cylinder containing the memory boards that hold the actual data. This connects to the various audio compressors that feed the information into the heart of the black box. There are various layers of materials protecting these memory boards, with an outer case made out steel or titanium covering layers of dry-silica insulation (to protect against heat) and an inner aluminium housing.

How tough are they?

To test the survivability of black boxes engineers subject them to a series of tests. These include crushing the unit in various places with pressures of up to 5,000 psi (pounds per square inch), firing it down an air cannon to create impact forces of 3,400 Gs (1G is Earth’s gravity) and cooking it in a fire for one hour at a temperature of 2,000 degrees Fahrenheit. (1,100 degrees Celsius).

In order to test the units’ ability to survive in water they are also immerse in pressurized tanks of salt water for 24 hours and non-pressurized tanks for 30 days.

The undersea navy drone that will be towed behind the Australian Defence vessel Ocean Shield to try and locate the black box.

How do investigators find them?

Black boxes are painted bright orange (the actual shade is ‘international orange’) to help with visibility and are equipped with water-activated beacons that send out ultrasonic pulses when the boxes hit water. These send out a pulse every second for thirty days after activation, transmitting their signal across ranges of 14,00 feet (4,267m). Two boats are currently searching for this beacon: one, a US submarine, and the second an Australian ship, the latter towing an underwater locator behind it close to the ocean floor.

Will they find MH370’s black box?

It’s possible but seems increasingly unlikely. Flight MH370 has been compared to Air France flight 447, which went missing over an ocean in 2009 for similarly mysterious reasons. It took two years for investigators to find the flight’s black box, and even then the discovery was described as a “minor miracle”, with the device happening to land on a sandy area at the bottom of the ocean floor, rather than among mountains crags and valleys.

The FDR black box from Air France flight 447 at the bottom of the sea in 2009.

Why aren’t black boxes better?

Although you can’t really beat black boxes in terms of survivability, on the face of it there does seem to be a lot of ways they could be improved. If your smartphone can record hours of video and beam that to your computer from anywhere in the world, why can’t black boxes send out more of their information? Ejectable black boxes that float on the ocean’s surface are already in use by the US Navy, so why don’t commercial flights have those?

Professor Krishna Kavi of the University of Texas suggests that it is “sheer institutional intertia” that is holding the industry back, with pilots fearing that advanced black boxes would lead to round-the-clock monitoring of their work. Others suggest that airlines’ profits are simply so razor-thin that they don’t want to invest in a technology that hardly makes for a comforting sales pitch: ‘if you crash, at least they’ll know why!’ Incidents like the disappearance of flight MH370 might help to push the industry into action, but even then, change is likely to be slow.

Life and Style
ebookNow available in paperback
ebooks
ebookA delicious collection of 50 meaty main courses
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
Independent Dating
and  

By clicking 'Search' you
are agreeing to our
Terms of Use.

ES Rentals

    iJobs Job Widget
    iJobs Gadgets & Tech

    Recruitment Genius: Mobile Applications Developer / Architect - iOS and Android

    Negotiable: Recruitment Genius: This is a great opportunity to join a medium s...

    Recruitment Genius: Trainee Programmer & IT Systems Technician

    £8000 - £10000 per annum: Recruitment Genius: This is a fantastic opportunity ...

    Recruitment Genius: 2nd Line IT Support Engineer

    £17500 - £20000 per annum: Recruitment Genius: A fantastic opportunity is now ...

    Recruitment Genius: Developer

    £35000 - £40000 per annum: Recruitment Genius: Are you familiar with the sayin...

    Day In a Page

    John Palmer: 'Goldfinger' of British crime was murdered, say police

    Murder of the Brink’s-MAT mastermind

    'Goldfinger' of British crime's life ended in a blaze of bullets, say police
    Forget little green men - aliens will look like humans, says Cambridge University evolution expert

    Forget little green men

    Leading evolutionary biologist says aliens will look like humans
    The Real Stories of Migrant Britain: An Algerian scientist adjusts to life working in a kebab shop

    The Real Stories of Migrant Britain

    An Algerian scientist struggles to adjust to her new life working in a Scottish kebab shop
    Bodyworlds museum: Dr Gunther von Hagens has battled legal threats, Parkinson's disease, and the threat of bankruptcy

    Dying dream of Doctor Death

    Dr Gunther von Hagens has battled legal threats, Parkinson's disease, and the threat of bankruptcy
    UK heatwave: Temperature reaches 39.8 degrees on Central Line - the sweatiest place in London

    39.8 degrees recorded on Tube

    There's hot (London) and too damn hot (the Underground). Simon Usborne braved the Central line to discover what its passengers suffer
    Kitchens go hi-tech: From robot chefs to recipe-shopping apps, computerised cooking is coming

    Computerised cooking is coming

    From apps that automatically make shopping lists from your recipe books to smart ovens and robot chefs, Kevin Maney rounds up innovations to make your mouth water
    Jessie Cave interview: The Harry Potter star has published a feminist collection of cartoons

    Jessie Cave's feminist cartoons

    The Harry Potter star tells Alice Jones how a one-night stand changed her life
    Football Beyond Borders: Even the most distruptive pupils score at homework club

    Education: Football Beyond Borders

    Add football to an after-school homework club, and even the naughtiest boys can score
    10 best barbecue books

    Fire up the barbie: 10 best barbecue books

    We've got Bibles to get you grilling and smoking like a true south American pro
    Wimbledon 2015: Nick Bollettieri - Junk balls and chop and slice are only way 5ft 1in Kurumi Nara can live with Petra Kvitova’s power

    Nick Bollettieri's Wimbledon Files

    Junk balls and chop and slice are only way 5ft 1in Kurumi Nara can live with Petra Kvitova’s power
    Ron Dennis exclusive: ‘This is one of the best McLaren teams ever – we are going to do it’

    ‘This is one of the best McLaren teams ever – we are going to do it’

    Ron Dennis shrugs off a poor start to the season in an exclusive interview, and says the glory days will come back
    Seifeddine Rezgui: What motivated a shy student to kill 38 holidaymakers in Tunisia?

    Making of a killer

    What motivated a shy student to kill 38 holidaymakers in Tunisia?
    UK Heatwave: Temperatures on the tube are going to exceed the legal limit for transporting cattle

    Just when you thought your commute couldn't get any worse...

    Heatwave will see temperatures on the Tube exceed legal limit for transporting cattle
    Exclusive - The Real Stories of Migrant Britain: Swapping Bucharest for London

    The Real Stories of Migrant Britain

    Meet the man who swapped Romania for the UK in a bid to provide for his family, only to discover that the home he left behind wasn't quite what it seemed
    Cheaper energy on the way, but it's not all sunshine and rainbows

    Cheaper energy on the way, but it's not all sunshine and rainbows

    Solar power will help bring down electricity prices over the next five years, according to a new report. But it’s cheap imports of ‘dirty power’ that will lower them the most