Aircraft Accident
Investigation
By:
Chinmay Patel
Roll No: 98001019
Outline
 History of Flight Data Recording
 Recording and Storage of Data
 Flight Data Recorder (FDR)
 Cockpit Voice Recorder (CVR)
 Crash Survivability Features
 Post Crash Procedures
 Information Retrieval
 Aircraft Reconstruction as a Technique
History
 Wright Brother’s
recording of propeller
rotations
 First Generation FDRs


Stainless Steel Tape
200 to 400 hrs of
information
 1958: 1st mandate in
USA
 1960: 1ST mandate in
UK
First Generation FDR
History
 1970s: Second
Generation FDRs


FDAUs introduced
Magnetic Tapes used
 1991: Solid State
Memory FDRs
 34 Parameters for 25
hrs
Second Generation FDR
Recording and Storage
 Magnetic Tapes


Track about 100 Parameters
30 minutes of CVR audio
 Solid State Memory Boards: Stacked array of
memory chips




No moving parts
More reliable
More Parameters (~ 700)
25 hrs of FDR data + 2 hrs of CVR audio
Data Acquisition
 Location on the Aircraft
FDR
 Sensors
FDAU
FDR
 Minimum of 11 to 29
Parameters to be
Recorded
 Eg: Time, Pressure
Altitude, Airspeed,
Heading, Accelerations,
Control Surface
Settings, Fuel Flow,
Engine RPM &
Temperature… etc
Solid State FDR
CVR
 Records all kinds of Cockpit Conversation,
Warning alerts & Noises
 Various Microphones in the Cockpit record
sounds
Pre-amplified
Digitized
Stored
 Re-write older material
 Provide an idea of the Crew’s Situation &
Decisions taken
Crash Survivability
 Crash Survivable
Memory Unit (CSMU)
 Damage resistant
features



Aluminum housing
Dry Silica Layer for
insulation
Steel/Titanium shell
 Thoroughly tested
against impact, fire and
environmental damage
Post Crash Procedures
 Locating the Black Box


Orange in color
Underwater Locator
Beacon



Pulses of 37.5 kHz
every second for 30
days
Can transmit sound
from 14000 ft under
water
Can be tracked by
Ultrasound Sensors

Black Boxes are transported
with utmost care
 Kept in environment identical
to that in which it was found
ULB
Information Retrieval
 Manufacturers supply NTSB with H/W & S/W
for Data Retrieval
 Team of experts interprets the data from FDR
and the CDR audio
 A typical team includes:




Airline representative
Airplane Manufacturer representative
NTSB Transportation-Safety Specialist
NTSB Air-Safety Investigator
Aircraft Reconstruction
 2D as well as 3D reconstruction
 Decide


Origin & Cause of Failure
Chain of Events
 Important investigation technique



Better understanding of Failure Modes
Helps in ruling out false theories
Assurance that no possibility is left out
Comet G-ALYP Reconstruction
 De Havilland Comet (1954)
 Mid-air Explosion: 35 lives lost
 Reconstruction provided clue to failure modes
 Culprit: Fatigue failure of the stressed skin
TWA 800 Reconstruction
 Boeing 747-131 (1996)
 Mid-air Explosion
 230 lives lost
 Several Controversies
 Reconstruction helped
to rule out false theories
 Total of 876 pieces
arranged
 Culprit: Explosion in
central fuel tank