Lecture 7: Flight Data Flashcards
flight data - what is purpose
to determine what (did not) happened
help investigators :
- identify issues that need further examination
-develop/validate/dismiss theories
-visualize what happen
communicate what happened to others and help them understand why it happened
what is the process
1-5
1 record data
2 access data
3 decode data
4 analyse data
5 communicate results
Flight data recording
Recorded data can come from many
different sources:
Onboard recording devices
-Purpose built
-Non-purpose built
Ground based storage of flight data.
-Flight data monitoring
-Maintenance data monitoring
Air traffic services
-Radar and audio data.
-ADS-B data
On board recorders
purpose built and non purpose built
Purpose built recorders
Mandated (crash survivable)
Non-mandated (non crash survivble)
Non purpose built
Electronic components with NVM
Portable units carried on board.
Progression of technology
First commercially available FDR’s
was in____
Digital recordings on magnetic tape (late ___’s)
in early 50’s in reaction to
several unsolved accidents
60’s
crash survivability - see slides
Regulatory Requirements
Flight data recorders (FDRs)
Cockpit Voice Recorders (CVRs)
Regulatory Requirements
Flight data recorders (FDRs)
Multi-engine turbine –powered aircraft with capacity for
* 10 or more passengers, manufactured after 1991
* 20 or more passengers otherwise.
Large cargo aircraft (CARs part 705
Cockpit Voice Recorders (CVRs
Multi-engine turbine –powered aircraft configured for 6 or
more passengers and requires 2 pilots
Coming soon
Light weight flight recorders (LDRs)
New ICAO Annex 6 requirements
* Lightweight Flight Recorders (ED155) for turbine-
powered aircraft <5700 kg.
* CVRs in smaller aircraft when operated by more
than one pilot ( >2250 kg)
Automatic Deployable
Flight Recorders (ADFR)
compare fdr parameters for B1900 A380 dee slide
Recovery
If wet, keep submerged
* If damaged, place in ESD
bag, and cover connectors
* Remove underwater locator
beacon (Li-ion
Getting to the data
Unit level recovery – Donor chasis
Unit level recovery – Direct
Chip level recovery
Making the data
readable
- Flight Data parameters are digital counts,
not engineering units. - They need to be decoded with the use of
data maps, different for every aircraft. - Slightly incorrect maps can cause
significant interpretation errors
Civilian “ARINC 573/717” Characteristic - (Military 1553):
Composed of fixed-length records of one second of data called
“subframes”.
* Subframes of size 64, 128, 256 or 512 words.
* Four subframes are called a “frame”.
* FDR “words” are 12 bits in size.
* First word in subframe is a known bit pattern called a “synchronization”
(sync) code. There are four unique sync codes in each frame
Cockpit Voice Recorders
Typically records 4
channels:
* Pilot
* Co-pilot
* Cabin area mic (CAM)
* Other source (variable)
The recordings are
protected by the TSB Act.
CVR Media
*Capacity is normally 2hrs, however for aircraft
manufactured before 2003 it’s only 30 minutes.
* There are two media types in use in Canada – solid state
and magnetic tape (still)
* Solid state are normally 2 hours, tape is normally 30
minutes.
* Not only is tape short, but it’s also less damage resistant
and difficult to access.
Accessing CVR data
CVR data is normally converted to WAV
format.
* Easy to work with
* Uncompressed
- With solid state, download and
conversion to WAV is easy. - With tape, it is difficult. Recordings are
played back on a reel to reel, and
digitized. - As the speed is never the same, the time
synchronization is normally out, and the
tracks need to be resampled
CVR transcriptions
CVR’s are normally transcribed so that data
can be quickly read, understood, and
communicated.
* Transcription is usually a group effort
* Not a precise science, more of a ‘best effort’
* Looping a small sound segment repeatedly is
very effective method.
* We normally use audacity to view the
waveform while listening; and
* Excel to make transcripts, so that time
synchronization is easier.
CVR Data
CVR audio contains MUCH more than just a record of the crew’s speech.
* Aural alerts
* GPWS callouts
* Airframe vibrations
* Engine vibrations
* Propeller speed
Quick Access Recorders
Purpose built recording, but not mandated, or damage tolerant.
* Developed in early 70s because many airlines (mostly
European) wanted to study flight data from not only incidents,
but also daily operations, for safety and maintenance purposes.
FDRs were difficult to download
due to crash protections
technology of the day and had
limited number of parameters
* These recorders are not
mandated or damage tolerant.
Typical QAR System
Tape Based Removal Cartridge/Laser Optical Disc
* 400 Hours recording time
* Exactly the same data stream as FDR
* No Standards for synchronization/format
QAR System Evolution
Many more parameters, and often higher sample rates
* Additional DFDAU with voluntary portion retrofitted
* More advanced ways to download, or transmit the data
What do operators do with this
data?
Airlines use this data for many purposes, including
* Operational control
* Maintenance tracking and trend monitoring
* Improving dispatch reliability,
* But perhaps most importantly for….
* Flight Operations Quality Assurance (FOQA)
Flight operations quality assurance
- FOQA, also known as Flight Data Monitoring (FDM) or Flight Data
Analysis (FDA) is part of an airline’s Safety Management System (SMS)
FOQA is the routine monitoring of de-identified flight data for the
purpose of
* Proactively identifying safety issues
* Recognizing trends; and
* Taking corrective action before situations worsen, such as
—>* Changes to procedures or training
* Sharing safety information with other operators.
The reactive and proactive cycle without
FOQA
see slides
see slides
How does FOQA help an
investigation?
Hopefully by preventing one.
- However, if an accident does happen and an investigation
is required, a review of historical FOQA/FDM data can; - Help determine if an event or underlying factor is an outlier or
systemic - If it is systemic, understand what factors are common amongst
the events
An example of how bulk FOQA/FDM data helps
- A DHC-8 was inbound to Sault Ste. Marie, at twilight with
reduced visibility due to an advancing weather system. - The aircraft’s approach became unstable at 200 feet, and
it drifted well below the glide path. - The crew lost visual reference, but continued
- The aircraft ‘landed’ short of the runway, and was
significantly damaged.
The move from isolated to systemic
Examination of the aircraft’s FDR determined that the aircraft’s
airspeed on approach was not stable, as required by the
operator’s procedures.
Examination of bulk
FOQA/FDM data was able
to determine that the
decelerating approach
was in fact systemic
amongst the entire fleet.
Other devices recording data
Aircraft, especially modern ones, are full of numerous different
things that aren’t intended as recorders, but are recording a lot of
data.
* Some of the most common units accessed following an event are
* Terrain awareness and warning systems (TAWS, GPWS, etc)
* Engine control units (ECUs, EECs, FADEC, etc).
* Flight control computers (FCCs)
* General rule of thumb is if it’s
computer controlled in some
way, it likely has memory.
nvm
non volatile memory
Portable sources
There are a few other sources of data, that might be found
in a aircraft, but aren’t necessarily part of the aircraft.
* Phones and tablets, especially if running foreflight or
similar.
* Phone based data recorders (Wi-flight)
* Handheld GPS.
Other types of
ground based
data
Data monitoring is
not limited to
airlines.
* Radar, Audio, ASDE,
MLAT, and ADS-B
data is also
monitored and
recorded.
Analyzing flight data
Before we can present the data we must
* Synchronize the data
* Data integrity checks
* Reasonableness checks
* Correlations checks
* Parameter source
* Etc..
Understanding the limitations of the data
* Sample rates
* Latencies
* Stale data
* Accuracy
* Resolution/Precision
Deriving parameters that aren’t recorded
* Trajectory
* True Airspeed
* Groundspeed
* Geometric height
* Height AGL
* Angle of attack
* Aerodynamic coefficients
How to look at the data
There are four common ways to look at flight data, and to
communicate this data with others.
* Tabular data / Spreadsheets
* Graphical Plots
* Geo-based flight paths
* Animations.
* Each has it’s advantages and disadvantages
Spreadsheets (Excel etc)
Advantages
* Easiest way to find an
exact number
Disadvantages
* Hard to visualize
* The extensive
amount of data can
be hard to scan
through
Graphical plots
Advantages
* Can summarize a lot of
data on one page
* Data can be limited to
what is relevant.
Disadvantages
* Hard to visualize
* Need to be studied to
notice significant
events
* Can be difficult for non
trained persons to
follow
Geo referenced flight paths
Advantages
* Easy to understand
and communicate
* Can often tell the
story in one photo.
Disadvantages
* Limited amount of
information
* Info is low fidelity
* May oversimplify the
event
Animations
Advantages
* Very effective way of
communicating
* Can help understand
how many details
interrelate
* Powerful and
compelling
* Easy to disseminate
Animation - Disadvantages
* Time consuming to get right.
* May present inaccuracies depending on
modeling
* Not great for understanding human factors
* Hard to get the weather / visibility / scenery
representative of the real condition
* Improvements being made with X-plane.
