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.

News
people'It can last and it's terrifying'
News
people Emma Watson addresses celebrity nude photo leak
Arts and Entertainment
tv
News
Katie Hopkins appearing on 'This Morning' after she purposefully put on 4 stone.
peopleKatie Hopkins breaks down in tears over weight gain challenge
PROMOTED VIDEO
Life and Style
ebooksA superb mix of recipes serving up the freshest of local produce in a delicious range of styles
Life and Style
ebooksFrom the lifespan of a slug to the distance to the Sun: answers to 500 questions from readers
Life and Style
fashionModel of the moment shoots for first time with catwalk veteran
Life and Style
fashionAngelina Jolie's wedding dressed revealed
Sport
Alexis Sanchez, Radamel Falcao, Diego Costa and Mario Balotelli
footballRadamel Falcao and Diego Costa head record £835m influx
News
i100
Arts and Entertainment
Madame Vastra and Jenny Flint kiss in Doctor Who episode 'Deep Breath'
tv
Arts and Entertainment
Olivia Colman topped the list of the 30 most influential females in broadcasting
tv
Life and Style
techIf those brochure kitchens look a little too perfect to be true, well, that’s probably because they are
Arts and Entertainment
Danish director Lars von Trier
tvEnglish-language series with 'huge' international cast set for 2016
Life and Style
tech
News
Kelly Brook
peopleA spokesperson said the support group was 'extremely disappointed'
Sport
Andy Murray celebrates a shot while playing Jo-Wilfried Tsonga
TennisWin sets up blockbuster US Open quarter-final against Djokovic
Arts and Entertainment
Hare’s a riddle: Kit Williams with the treasure linked to Masquerade
booksRiddling trilogy could net you $3m
Arts and Entertainment
Alex Kapranos of Franz Ferdinand performs live
music Pro-independence show to take place four days before vote
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

    Systems Administrator (SharePoint) - Central London - £36,500

    £35000 - £36500 per annum: Ashdown Group: Systems Administrator (SharePoint) -...

    Derivatives Risk Commodities Business Analyst /Market Risk

    £600 - £800 per day: Harrington Starr: Derivatives Risk Commodities Business A...

    Power & Gas Business Analyst / Subject Matter Expert - Contract

    £600 - £800 per day: Harrington Starr: Power & Gas Business Analyst/Subject Ma...

    Infrastructure Lead, (Trading, VCE, Converged, Hyper V)

    £600 - £900 per day: Harrington Starr: Infrastructure Lead, (Trading infrastru...

    Day In a Page

    'I’ll tell you what I would not serve - lamb and potatoes': US ambassador hits out at stodgy British food served at diplomatic dinners

    'I’ll tell you what I would not serve - lamb and potatoes'

    US ambassador hits out at stodgy British food
    Radio Times female powerlist: A 'revolution' in TV gender roles

    A 'revolution' in TV gender roles

    Inside the Radio Times female powerlist
    Endgame: James Frey's literary treasure hunt

    James Frey's literary treasure hunt

    Riddling trilogy could net you $3m
    Fitbit: Because the tingle feels so good

    Fitbit: Because the tingle feels so good

    What David Sedaris learnt about the world from his fitness tracker
    Saudis risk new Muslim division with proposal to move Mohamed’s tomb

    Saudis risk new Muslim division with proposal to move Mohamed’s tomb

    Second-holiest site in Islam attracts millions of pilgrims each year
    Alexander Fury: The designer names to look for at fashion week this season

    The big names to look for this fashion week

    This week, designers begin to show their spring 2015 collections in New York
    Will Self: 'I like Orwell's writing as much as the next talented mediocrity'

    'I like Orwell's writing as much as the next talented mediocrity'

    Will Self takes aim at Orwell's rules for writing plain English
    Meet Afghanistan's middle-class paint-ballers

    Meet Afghanistan's middle-class paint-ballers

    Toy guns proving a popular diversion in a country flooded with the real thing
    Al Pacino wows Venice

    Al Pacino wows Venice

    Ham among the brilliance as actor premieres two films at festival
    Neil Lawson Baker interview: ‘I’ve gained so much from art. It’s only right to give something back’.

    Neil Lawson Baker interview

    ‘I’ve gained so much from art. It’s only right to give something back’.
    The other Mugabe who is lining up for the Zimbabwean presidency

    The other Mugabe who is lining up for the Zimbabwean presidency

    Wife of President Robert Mugabe appears to have her sights set on succeeding her husband
    The model of a gadget launch: Cultivate an atmosphere of mystery and excitement to sell stuff people didn't realise they needed

    The model for a gadget launch

    Cultivate an atmosphere of mystery and excitement to sell stuff people didn't realise they needed
    Alice Roberts: She's done pretty well, for a boffin without a beard

    She's done pretty well, for a boffin without a beard

    Alice Roberts talks about her new book on evolution - and why her early TV work drew flak from (mostly male) colleagues
    Get well soon, Joan Rivers - an inspiration, whether she likes it or not

    Get well soon, Joan Rivers

    She is awful. But she's also wonderful, not in spite of but because of the fact she's forever saying appalling things, argues Ellen E Jones
    Doctor Who Into the Dalek review: A classic sci-fi adventure with all the spectacle of a blockbuster

    A fresh take on an old foe

    Doctor Who Into the Dalek more than compensated for last week's nonsensical offering