Flight International - January 13, 2015

36 | Flight International | 13-19 January 2015 flightglobal.com

AIRLINE SAFETY

❯❯ and systems data, plus cockpit communi-

cation and ambient sound, to help investiga-
tors determine what happened in the event of
an accident. The position of a crashed aircraft
is not provided by a standard FDR, but by sepa-
rate ELT embedded elsewhere in the aircraft.
Today’s aircraft ELTs are activated by im-
pact-caused deceleration to transmit an emer-
gency signal that search teams can home in
on. If the ELTs fail (there are usually two),
there is a risk the aircraft and its data/voice
recorders will not be found – or not for a long
time anyway. ELTs also have limited range, a
broadcasting life of about 30 days, and they
do not have sufficient power to provide an
above-water signal if the wreckage comes to
rest on a deep sea-bed.
In its recommendations in the AF447 final
accident report, French accident investigation
agency BEA recommended the use of deploy-
able FDRs with embedded ELTs so it would
never again take so long to find and download
a “black box” recorder. A DFDR in the AF447
A330 would have been deployed either on
impact with the sea or triggered by other
agreed parameters. In any case, it would have
been designed to float so its locator signal
would have been picked up by search teams.

HYBRID
The last signals from a standard flight tracking
system would help rescuers and investigators
find an aircraft after an accident even if the air-
craft’s ELT failed, but it does not supply aircraft
operational and engineering data – only the
FDR/CVR does that. There is, however, a hy-
brid system which can enable position track-
ing and also transmission of real-time aircraft
data via a datalink, like the well-established
ACARS can be set up to do. Canada-based
Flyht Aerospace Solutions offers such a hybrid
system. Under the brand-name FLYHT, the

company offers several products and backup

services. One of them, called AFIRS UpTime,

allows airlines to monitor and manage aircraft

operations anywhere in real time. In an emer-

gency, a triggered data-streaming mode mar-

keted as FLYHTStream automatically sends

FDR data and position information to desig-

nated sites on the ground in real-time.

A serious issue raised by what happened to

MH370 is this: whatever system is ultimately

chosen, the authorities have to consider

whether it should be designed to be tamper-

proof. This issue arises because, for unknown

reasons the MH370 aircraft’s ACARS and sec-

ondary radar transponder stopped transmitting

not long after departure, but just before the air-

craft turned away from its flight planned route.

The most widely-proposed theory for this is

that the act of switching off the signals and the

diversion from the flight plan was a deliberate

action by someone on board. But what ICAO

and the industry has to consider is whether the

inability of a crew to isolate any piece of elec-

trical equipment is an unacceptable fire risk,

especially in the light of the fact that deliberate

acts to harm aircraft and their passengers by

flying them to their doom are vanishingly rare.

FLOATING CONCEPT

In May 2014, ICAO set up the ATTF to be co-

ordinated by IATA, and in parallel with this,

the organisation aims to develop a concept of

operations covering how the new tracking

data would be shared, with whom, and under

what circumstances. It is all very well saying

flights must be trackable anywhere, but track-

ing could be carried out for malign as well as

benign reasons.

The Airbus DFDR concept involves de-

ploying one of two FDR/CVR “black boxes” in

the event of a mid-air collision or impact with

the ground, one embedded and the other de-

ployable. The deployed unit would include a

locator beacon, and be designed to float if a

crash occurs in water. In the case of the Yem-

enia crash in 2009 – which involved impact

with the sea close to shore while the aircraft

was positioning to land at night – a floating

locator beacon might have saved lives. One

passenger was found alive, but others may po-

tentially have been saved too.

One of the Airbus suppliers at the US Na-

tional Transport Safety Board forum, Honey-

well vice-president of aerospace regulatory af-

fairs Chris Benich, described how a deployable

recorder would work.

The system first senses the start of a crash

sequence and releases the deployable recorder

from the aircraft. In a previous patent filing,

Airbus described the installation as a lower

panel in aft fuselage near the tail cone. If the

system lands on water, it is designed to float

indefinitely, with a locator beacon alerting

search crews of its presence. A purpose-built

DFDR also has the potential to address a chron-

ic reliability problem for existing ELTs. Each

commercial aircraft is required to carry two,

but they often do not survive the crash. Airbus

statistics show that ELTs were activated in only

28% of reviewed incidents. ■

It is all very well saying

flights must be trackable, but

tracking could be carried out

for malign or benign reasons

Existing ELTs are located apart from the FDR and have a broadcasting life of only about 30 days

France’s BEA recommended use of deployable

FDRs with ELTs after the AF447 accident

Rex Features

Rex Features