In an earlier post I commented that in the QF72 incident the use of a geometric mean (1) instead of the arithmetic mean when calculating the aircrafts angle of attack would have reduced the severity of the subsequent pitch over. Which leads into the more general subject of what to do when the real world [...]
Archive for the ‘Aerospace Safety’ Category
Spiky Data, Means, Medians and Memes
Posted in Aerospace Safety, Fault tolerance, Uncategorized, tagged arithmetic, geometric, Population statistics, QF 72, spiky data on 23/12/2011 | 1 Comment »
On Possibilistic Design and Aviation Safety
Posted in Aerospace Safety, Complexity, Epistemic Risk, fail safe, Uncertainty, tagged AC 25.1309-1 (1988), DO-178B, FAR Part 25, Fukushima, IEC 61508, John Downer, Myth of Mechanical Objectivity, Possibilistic, Probabilistic, Risk on 11/12/2011 | 3 Comments »
I’ve recently been reading John Downer on what he terms the Myth of Mechanical Objectivity. To summarise John’s argument he points out that once the risk of an extreme event has been ‘formally’ assessed as being so low as to be acceptable it becomes very hard for society and it’s institutions to justify preparing for it.
Pilots in the Loop? Airbus and the FBW Side Stick
Posted in Aerospace Safety, Cognitive psychology, Human error, The human machine interface, Violations, tagged AF 447, AirBus, ATSB, crew coordination, FBW, NTSB, side stick controller on 16/09/2011 | 2 Comments »
Airbuses side stick improves crew comfort and control, but is there a hidden cost? The Airbus FBW side stick flight control has vastly improved the comfort of aircrew flying the Airbus fleet, much as the original Airbus designers predicted (Corps, 188). But the implementation also expresses the Airbus approach to flight control laws and that [...]
Out of the Loop
Posted in Aerospace Safety, Cognitive psychology, Uncertainty, tagged attentional tunneling, automation cost, Bayesian reasoning\, cry wold effect, human error, perceptual biases on 14/08/2011 | 2 Comments »
The BEA’s third interim report on AF 447 highlights the vulnerability of aircrew when their usually highly reliable automation fails in the challenging operational environment of high altitude flight.
The Titanic Effect (Part II)
Posted in Aerospace Safety, Assumptions, tagged AF 447, AirBus, assumptions, Titanic on 07/08/2011 | Leave a Comment »
Thinking about the unintentional and contra-indicating stall warning signal of AF 447 I was struck by the common themes between AF 447 and the Titanic. In both the design teams designed a vehicle compliant to the regulations of the day. But in both cases an implicit design assumption as to how the system would be operated was invalidated.
What the BEA didn’t say about Air France AF 447
Posted in Aerospace Safety, Errors, tagged AF 447, airbus aircraft, attensity, BEA Investigation, BEA report, crew resources, human factors, safety management system, safety thread, stall recovery on 05/08/2011 | Leave a Comment »
The BEA third interim report on the AF 447 accident raises questions So I’ve read the BEA report from one end to the other and overall it’s a solid and creditable effort. The report will probably disappoint those who are looking for a smoking gun, once again we see a system accident in which the [...]
Side Sticks and Shared Situational Awareness
Posted in Aerospace Safety, Human error, The human machine interface, tagged AF447, AirBus, centre stick controller, cockpit error management, crew resource management, Risk, Safety, side stick controller on 27/07/2011 | 3 Comments »
One of the less often considered aspects of situational awareness in the cockpit is the element of knowing what the ‘guy in the other seat is doing’. This is a particularly important part of cockpit error management because without a shared understanding of what someone is doing it’s supremely difficult to detect errors. The replacement of the central control stick with side stick ‘glass’ controllers eliminates a little acknowledged means of coordinating a common understanding of control inputs between aircrew with the potential for a hazardous loss of crew error management.
On the Brittleness of Software
Posted in Aerospace Safety, Human error, The human machine interface, tagged AF447, Air France, design assumptions, design paradigm, epistemic risk, James Reason, never give up design strategy, requirements incompleteness, Software latent fault, stall warning on 23/07/2011 | 3 Comments »
Reading through the BEA’s precis of the data contained on AF447′s Flight Data Recorder you find that during the final minutes of AF447 the aircrafts stall warning ceased, even though the aircraft was still stalled. This loss of stall warning removed a significant cue to the aircrew that they had flown the aircraft into a deep stall, undoubtedly adding to their confusion. SU4CF4KDVSWQ
QF 32 and Checklists
Posted in Aerospace Safety, Cognitive psychology, The human machine interface, tagged ATSB, automated checklists, cognitive limitations, ECAM, multiple failures, QF32 on 11/07/2011 | Leave a Comment »
According to the preliminary ATSB report the crew of QF32 took approximately 50 minutes to process all the Electronic Centralised Aircraft Monitor (ECAM) messages. So, two questions for the ATSB. First would the normal three man crew have been able to handle the ECAM checklist work as readily? Second should the checklist processing have taken 50 minutes which is a very, very, long time in a mid air emergency?
Pitch Ladders and Unusal Attitude Recovery
Posted in Aerospace Safety, Cognitive psychology, The human machine interface, tagged AF447, F16, HUD, partially articulated, PFD, pitch ladder, Primary Flight Display, unusual attitude recovery, US DoD on 05/07/2011 | Leave a Comment »
Because they have typically pitch unity ratios (1:1) scales, aircraft primary flight displays provide a pitch display that is limited by the vertical field of view. This display can move very rapidly and be difficult to use in unusual attitude recoveries becoming another adverse performance shaping factor for aircrew in such a scenario. Trials by the USAF have conclusively demonstrated that an articulated style of pitch ladder can reduce disorientation of aircrew in such situations.
Planes and Trains
Posted in Aerospace Safety, Safety culture, Technology, tagged DDAAFS, RAAFSafe, Rail Safety 2011, safety culture, safety management system on 05/07/2011 | 1 Comment »
I attended the annual Rail Safety conference for 2011 earlier in the year and one of the speakers was Group capt Alan Clements, the Director Defence Aviation Safety and Air Force Safety. His presentation was interesting in both where the ADO is going with their aviation safety management system as well as providing some historical perspective, and statistics.
Is this Human Error?
Posted in Aerospace Safety, Violations, tagged Bud Holland, Canberra bomber, Czar 52, James Reason, Procedural violation, RAAF on 30/06/2011 | Leave a Comment »
James Reason would classify this as a violation rather than error, that is a deliberate departure from an approved procedure. But this is where we get into the cultural and organisational aspects of such behaviour.
Flying in the Rear View Mirror
Posted in Aerospace Safety, Decision making, tagged cognitive bias, get there itis, NASA, plan continuation bias, Safety, sunk cost heuristic on 26/06/2011 | Leave a Comment »
Plan continuation bias is a recognised and subtle cognitive bias that tends to force the continuation of an existing plan or course of action even in the face of changing conditions. In aerospace safety it is recognised as a significant causal factor in accidents with a NASA study finding that in 9 out of the 19 accidents studied aircrew exhibited this behavioural bias. The economic theory of the ‘sunk cost heuristic’ may provide a simple explanation.
Let Slip the Wolves of Error
Posted in Aerospace Safety, Human error, tagged Cry Wolf effect, Unreliable air data on 26/06/2011 | Leave a Comment »
In a series of aircraft incidents air crew have consistently demonstrated difficulty in first identifying and then dealing with unreliable air data and warnings. To me figuring out why this difficulty occurs is essential to addressing a significant air safety problem.
A Thing Called Hindsight and AF447
Posted in Aerospace Safety, Human error, tagged AF447, error patterns, Hindsight bias, human error, just world hypothesis, NASA Ames on 23/06/2011 | Leave a Comment »
Knowing the outcome of an accident flight does not ‘explain’ the accident Hindsight bias and it’s mutually reinforcing cognitive cousin the just world hypothesis are traditional parts of public comment on a major air accident investigation when pilot error is revealed as a causal factor. The public comment in various forum after the release of the [...]
AF447… What We Now Know
Posted in Aerospace Safety, Human error, tagged accident sequence, AF 447, AF447, Air France, AirBus, BEA Investigation, epistemic risk, Fault tolerance, human machine interface, system architecture on 27/05/2011 | 12 Comments »
The BEA has released a precis of the data contained on AF447′s Flight Data Recorder and we can know look into the cockpit of AF447 in those last terrifying minutes.
Who’s Really Responsible in the Cockpit?
Posted in Aerospace Safety, Ethics, tagged avatar, ethics, FAR 91.3, legal, protection laws, requirements, responsibility, software agent, specification on 24/05/2011 | 4 Comments »
Over the years a recurring question raised about the design of FBW aircraft has been whether pilots constrained by software embedded protection laws really have the authority to do what is necessary to avoid an accident? But this question falls into the trap of characterising the software as an entity in and of itself. The real question is should the engineers who developed the software be the final authority?
UAV and COMAIR Near Miss … Somewhere over Kabul
Posted in Aerospace Safety, Complexity, tagged AI, air traffic, assumptions, deconfliction, hazard analysis, interaction hazard, Kabul, RPV, system hazard, UAV on 19/05/2011 | Leave a Comment »
A UAV and COMAIR near miss over Kabul illustrates the problem of emergent hazards when we integrate systems.
An Architectural Lesson From Apollo 13
Posted in Aerospace Safety, Common cause failures, Heuristics & Biases, System architecting, tagged Apollo 13, architectural decision, O2 tank rupture, space shuttle replacement on 16/05/2011 | Leave a Comment »
A near disaster in space 40 years ago serves as a salutory lesson on common cause failure.
Why We Risk…
Posted in Aerospace Safety, Logic of Scientific Discovery, Uncertainty, tagged epistemic risk, experience base, knowledge, LLTV, Luna Lander Test Vehicle, NASA, Neil Armstrong, risk averse on 15/05/2011 | Leave a Comment »
Why taking risk is an inherent part of the human condition.
I tend towards the integrative rather than reductionist view of engineering and science. I'm interested in emergence, networks, relationships and interfaces as they apply to safety.what are the facts?
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