The operators recurrent simulator training did not address the recovery from a stall or stick shaker activation such that the ongoing competency of their flight crew was not assured.
The operators procedures did not include a validation check of the landing weight generated by the flight management system which resulted in lack of assurance that the approach and landing speeds were valid.
The available Cross Crew Qualification and Mixed Fleet Flying guidance did not address how flight crew might form an expectation, or conduct a ‘reasonableness' check, of the speed/weight relationship for their aircraft during takeoff.
One of the aircraft’s three air data inertial reference units (ADIRU 1) exhibited a data-spike failure mode, during which it transmitted a significant amount of incorrect data on air data parameters to other aircraft systems, without flagging that this data was invalid. The invalid data included frequent spikes in angle of attack data. Including the 7 October 2008 occurrence, there have been three occurrences of the same failure mode on LTN-101 ADIRUs, all on A330 aircraft.
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.
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.
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.
Industry practices for tracking faults or performance problems with line-replaceable units are limited, unless the units are removed for examination. Consequently, the manufacturers of aircraft equipment have incomplete information for identifying patterns or trends that can be used to improve the safety, availability or reliability of the units.
Single event effects (SEE) have the potential to adversely affect avionics systems that have not been specifically designed to be resilient to this hazard. There were no specific certification requirements for SEE, and until recently there was no formal guidance material available for addressing SEE during the design process.
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.
Although passengers are routinely advised after takeoff to wear their seat belts when seated, this advice typically does not reinforce how the seat belts should be worn.
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.
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.
There was a limitation in the algorithm used by the A330/A340 flight control primary computers (FCPCs) for processing angle of attack (AOA) data. This limitation meant that, in a very specific situation, multiple spikes in AOA from only one of the three ADIRUs could result in a nose-down elevator command.
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.
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 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.
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.
The failure of the digital flight data recorder (DFDR) rack during the tail strike prevented the DFDR from recording subsequent flight parameters.
