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CAA UK issues Aircraft Maintenance Incident Analysis Paper
4 December 2007

Report: UK Safety Performance detailing U.K. safety statistics 2000-2009

The U.K. Civil Aviation Authority (CAA) published a statistical review of aviation safety, titled “UK Safety Performance” (CAP 800).

The document provides statistics on the safety of UK aviation between 2000 and 2009, covering reportable and fatal accidents, serious incidents and occurrences as a whole.Information is provided for UK public transport, UK non-public transport, UK airspace and UKaerodromes, large and small aeroplanes, helicopters, airships, balloons, gliders, gyroplanesand microlights.

There were 113 reportable accidents involving large UK public transport aeroplanes between 2000 and 2009. The most common type of accident was a ramp incident, followed by abnormal runway contact or runway excursion. Three accidents involved fatalities to aircraft occupants, with a total of five fatalities. One accident involved a third party fatality.

The reportable accident rate over the period as a whole was 9.8 per million flights, and the fatal accident rate was 0.3 per million flights. Grouping aircraft into jets, business jets and turboprops, the group most commonly involved in a reportable accident was jet aircraft, but they had the lowest accident rate at 9.1 per million flights. By contrast, business jets were involved in the least number of reportable accidents but had the highest accident rate at 19.4 per million flights.

In addition to the five on-board fatalities and one third-party fatality, there were 15 serious injuries and 44 minor injuries.

There were 179 serious incidents, of which aircraft technical failure/malfunction was the most common type of serious incident, followed by in-flight fire/smoke/fumes. The serious incident rate was 15.7 per million flights, and was highest for turboprop aircraft at 20.1 per million flights.

Overall, there were 49,000 occurrences involving large UK public transport aeroplanes and the annual number of these occurrences increased by 20% in the ten year period. Accidents and Serious Incidents form less than 1% of the total number of occurrences.

More information:

Study: Aircraft loading occurrences July 2003 to June 2010

Incorrect unloading can cause an aircraft to pitch up (photo: ATSB)

The Australian Transport Safety Bureau (ATSB) published a study (AR-2010-044) on aircraft loading occurrences from July 2003 to June 2010.

The report documents the number and types of safety occurrences involving loading of high capacity aircraft to raise awareness within the aviation industry of the associated issues.
Incorrect loading of containers, pallets or bags into aircraft can result in them being outside of weight or centre of gravity operating limits, and this may influence aircraft controllability. Most high capacity aircraft loading occurrences are relatively minor, with cargo locks not being raised being the most common. More serious occurrences have involved shifting cargo and unlisted cargo being loaded onto aircraft. Aircraft performance has been affected in a small number of cases, and the result has been rejected takeoff, extra stabiliser trim, or aircraft control difficulties.

The study concluded that the following practices can help to guard against common loading errors:

  • Perform cross-checks between the mean aerodynamic chord and stabiliser trim setting, for all LIRs.
  • Perform a cross-check of the aircraft weight, as recorded in the aircraft manual –  with the load report weight, and ensure the aircraft registration details are correct on the loadsheet.
  • Flight crew should not accept a loadsheet while the aircraft is being loaded.
  • Incorporate rules within load  control software that stop incorrectly configured aircraft loadsheets from being generated.
  • Remove off-loaded/rejected containers or loads from next to the aircraft where they can potentially get reloaded in error.
  • Use on-board aircraft weight sensors as a cross-check against weight and centre of gravity calculations.

 

Study: Steady increase in Australian birdstrikes

A new report released by the Australian Transport Safety Bureau (ATSB) highlights ways to manage the risks posed by aircraft hitting birds and reveals that the reported number of  birdstrikes in Australia has steadily increased over the past eight years.

The report, which provides aviation birdstrike and animal strike occurrence data between January 2002 and December 2009, shows that in 2009 alone there were 1,340 birdstrikes reported to the ATSB.

The increase in the number of birdstrikes, however, is consistent with the increase in the number of high capacity aircraft movements over the period as well as a greater willingness of people in aviation to report safety occurrences to the ATSB.

Most birdstrikes occur within the confines of aerodromes (less than 5 km). Major and regional towered aerodromes had significantly higher rates of reported birdstrikes than General Aviation Airport Procedures (GAAP) aerodromes, and had considerably increasing rates from 2002 to 2009. GAAP aerodrome birdstrike rates do not appear to have changed.

Engine ingestion makes up 11 per cent of all birdstrike occurrences in high capacity air transport for the 8- year period, and the highest number of damaging birdstrikes occurs in high capacity air transport. Birdstrikes causing multiple parts damaged were not common throughout the period. General aviation had the highest proportion of damaging birdstrikes, with almost 24 per cent of birdstrikes causing damage. Aeroplane wings and helicopter rotor blades are the most commonly damaged aircraft components across all operational types, particularly in general aviation. There have been eight occurrences from the period of 2002-2009 that have resulted in serious aircraft damage, and four that have resulted in injury.

The most common types of birds struck by aircraft were lapwings/plovers, bats/flying foxes, galahs, and kites. Not surprisingly, larger birds were more likely to result in aircraft damage.

Animal strikes were relatively rare. High capacity air transport had the highest average with 11.5 animal strikes per year, with general aviation having the second highest average with 9.3 animal strikes per year. The most common animals involved in strikes were hares/rabbits, kangaroos, wallabies, and foxes/dogs. Damaging strikes mostly involved kangaroos, wallabies and livestock.

Bird hazard control at aerodromes was found to be mostly related to the control of grass height (short or long) and growing specific plants or grass, and the daily or weekly use or auditory deterrents, especially car horns and shotguns.

Study: Factors influencing misaligned take-off occurrences at night

ATSB pilot information card to help flight crew identify factors that could increase the risk of a misaligned take-off or landing.

The Australian Transport Safety Bureau (ATSB) published a study into factors influencing misaligned take-off occurrences at night. This report examines both Australian as well as relevant international occurrences
where pilots have misperceived their lateral position on runway due to darkness and a combination of individual influences, runway, weather and task conditions.

The study was iniated following several occurrences that involved aircraft commencing takeoff on the runway edge lighting. All five recent Australian misaligned take-off and landing occurrences involved aircraft with weights greater than 5,700kg and three of the six occurrences involved scheduled regular passenger transport operations. The remaining two occurrences involved charter operations.

After reviewing the Australian and international occurrences, eight common factors were identified that increased the risk of a misaligned take-off or landing occurrence. The factors included:

  • distraction or divided attention of the flight crew;
  • confusing runway layout; displaced threshold or intersection departure;
  • poor visibility or weather; air traffic control clearance/s issued during runway entry;
  • no runway centreline lighting;
  • flight crew fatigue; and
  • recessed runway edge lighting

To foster safety awareness, knowledge and action, the ATSB developed a pilot information card to help flight crew identify factors that could increase the risk of a misaligned take-off or landing.

Report: Ground operations occurrences at Australian airports 1998 to 2008

The Australian Transport Safety Bureau (ATSB) released a study of ground operations occurrences at Australian airports from 1998 to 2008. The key to preventing ground occurrences appears to revolve around ensuring effective communication between pilots, ground crews and air traffic services through a process of checks and balances.

The aviation industry has been slow to acknowledge the risks associated with ground operations. While most occurrences on airport aprons and taxiways do not have consequences in terms of loss of life, they are often associated with aircraft damage, delays to passengers and avoidable financial costs to industry.
The most common contributing factor to ground operations occurrences were individual actions. For occurrences between 1998 and 2008, these most frequently involved action errors, where a person deviated either from plans or standard operating procedures. Common examples were towbar connection procedures and pushback errors, like turning back too sharply with the tug and damaging the nose or landing gear of the aircraft. Less frequently, individual action errors were associated with a violation, information, or decision error. Violations involved a deliberate intention to deviate from standard operating procedures. Examples included opening the doors while the aircraft anti-collision beacon was operating, or vehicle drivers failing to give-way to aircraft on the apron or taxiways. Decision errors indicated that planned actions were not adequate for the situation; for example,

CAA UK issues Aircraft Maintenance Incident Analysis Paper

The U.K. CAA released the results of an analyses of a selection of maintenance related events on jet aircraft above 5,700kg MTOW, captured and stored under the requirements of the CAA’s Mandatory Occurrence Reporting (MOR). The data showed that the vast majority of MORs were related to Equipment and Furnishings, escape slides in particular. The study concludes that the number of maintenance related MORs as a percentage of the total number of MORs submitted to the CAA appears to decrease steadily from 2000 to 2005. This reduction may, in part, be attributable to the extensive efforts of the CAA to promote human factors awareness training, guidance and policy within the industry. Recommendations include improving the consistency and comprehensiveness of data captured to facilitate future trend analysis, and identification of the underlying causes of maintenance error. (CAA)