When developing the A330/A340 flight control primary computer software in the early 1990s, the aircraft manufacturer’s system safety assessment and other development processes did not fully consider the potential effects of frequent spikes in the data from an air data inertial reference unit.
For the data-spike failure mode, the built-in test equipment of the LTN 101 air data inertial reference unit was not effective, for air data parameters, in detecting the problem, communicating appropriate fault information, and flagging affected data as invalid.
There has been very little research conducted into the factors influencing passengers’ use of seat belts when the seat-belt sign is not illuminated, and the effectiveness of different techniques to increase the use of seat belts.
In recent years there have been developments in guidance materials for system development processes and research into new approaches for system safety assessments. However, there has been limited research that has systematically evaluated how design engineers and safety analysts conduct their evaluations of systems, and how the design of their tasks, tools, training and guidance material can be improved so that the likelihood of design errors is minimised.
Although passengers are routinely reminded to keep their seat belts fastened during flight whenever they are seated, a significant number of passengers have not followed this advice. At the time of the first in-flight upset, more than 60 of the 303 passengers were seated without their seat belts fastened.
The LTN-101 air data inertial reference unit (ADIRU) model had a demonstrated susceptibility to single event effects (SEE). The consideration of SEE during the design process was consistent with industry practice at the time the unit was developed, and the overall fault rates of the ADIRU were within the relevant design objectives.
The existing take-off certification standards, which were based on the attainment of the take-off reference speeds, and flight crew training that was based on monitoring of and responding to those speeds, did not provide crews a means to detect degraded take-off acceleration.
The lack of a designated position in the pre-flight documentation to record the green dot speed precipitated a number of informal methods of recording that value, lessening the effectiveness of the green dot check within the loadsheet confirmation procedure.
Operation of the M-18A in accordance with Civil Aviation Safety Authority exemptions EX56/07 and EX09/07 at weights in excess of the basic Aircraft Flight Manual maximum take-off weight (MTOW), up to the MTOW listed on the Type Certificate Data Sheet, may not provide the same level of safety intended by the manufacturer when including that weight on the Type Certificate.
A number of operators of the PZL M-18 Dromader aircraft had not applied the appropriate service life factors to the aircraft’s time in service for operations conducted with take-off weights greater than 4,700 kg, as required by the aircraft’s service documentation. Hence the operators could not be assured that their aircraft were within their safe service life.
The failure of the digital flight data recorder (DFDR) rack during the tail strike prevented the DFDR from recording subsequent flight parameters.
The operator’s training and processes in place to enable flight crew to manage distractions during the pre-departure phase did not minimise the effect of distraction during safety critical tasks.
The lack of a requirement for a charter-specific risk assessment in this case meant that the risks associated with the charter were not adequately addressed.
The procedural and guidance framework for commercial balloon operations generally, did not provide a high level of assurance in regard to the safe conduct of low flying.
A number of non-cold rolled bolts were installed on PT6A-67 series engines during manufacture and overhaul
The Society of Automotive Engineers specification AS7477 was ambiguous in relation to the requirement to cold roll the head-to-shank fillet radius of MS9490-34 bolts.
The scheduled maintenance requirements for ex-military UH-1 series helicopters may not adequately address the increased risk of fatigue failures associated with repetitive heavy lifting operations that were not considered in the original design fatigue calculations.
There was no correlation between the results of the operator’s Flight Operational Quality Assurance and Air Safety Incident Report investigations.
There were no soft and hard triggers in the operator’s Flight Operational Quality Assurance system to monitor the selection of the aircraft’s landing gear during an approach.
The conflicting requirements and definitions in the operator’s publications in relation to the pilot not flying role had the potential to diminish the importance of monitoring as an essential element in an aircraft’s safe operation.
