Report: No change in numbers of U.K. airprox incidents involving commercial aircraft in 2010

December 9, 2011

The number of airprox incidents in the United Kingdom involving commercial passenger aircraft remained static in 2010, according to a report by the UK Airprox Board (UKAB).
There were 35 incidents involving passenger aircraft in 2010, the same number as 2009. The majority of these incidents involved the airliner conflicting with a military or general aviation light aircraft. However, for the first time in over 10 years none of these incidents were regarded as ‘risk-bearing’.

As it published its 2010 data analysis, the UK Airprox Board (UKAB) said that year-on-year airspace conflicts involving two commercial aircraft had halved, with only 5 incidents in 2010 compared to 11 in 2009. The steady decline in these types of incidents from the early 2000s (in 2002 there were 39 such incidents) is due a combination of factors including the airline industry’s adoption of sophisticated collision avoidance systems and the combined efforts of operators and air traffic controllers tackling the issue.

Overall, however, the total numbers of incidents increased on 2009, with 167 incidents in 2010, compared to 147 the previous year, largely as a result of an upturn in conflicts involving military and general aviation aircraft.

UKAB reports, produced jointly for the Chairman of the Civil Aviation Authority and the Chief of the Air Staff, Royal Air Force, are principally aimed at UK pilots and air traffic controllers, both civil and military. Their purpose is to promote air safety awareness and understanding by identifying and sharing the lessons arising from UK Airprox incidents.

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Slight rise in U.K. airprox incidents in 2010

May 12, 2011

The latest report from the UK Airprox Board (UKAB) shows an improvement during the first six months of 2010 in the most serious airprox incidents involving commercial air transport aircraft, with no reported events at all concerning passenger airlines in the highest risk categories. There had been one category B incident during the first six months of 2009.

There was, however, a small overall increase in reported airprox incidents between January-June 2010 compared to the same period the year before. There were a total of 79 incidents in the first half of 2010 involving commercial, military and general aviation aircraft, in contrast to 60 during January to June 2009.

General aviation aircraft were involved in ten more incidents than in the same period the year before – 44 compared to 34. These included two category A incidents, an increase on the single category A incident during the same period in 2009.

Today’s report shows that the causes of airprox incidents remain predominantly late sightings and non-sightings of aircraft by pilots. The majority of these occur in Class G (uncontrolled) airspace where pilots have the responsibility to see and avoid other aircraft.

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Report: ATR-72 control difficulties following rudder maintenance

April 18, 2011

The U.K. AAIB published a Special Bulletin including three safety recommendations regarding control difficulties that were encountered by the crew of an ATR-72 during a post-maintance flight.

The aircraft had undergone routine maintenance at an engineering facility at Edinburgh Airport immediately prior to the incident flight.
Everything appeared normal during the crew’s pre-flight checks, which included a full-and-free check of the flying controls.
The aircraft took off at 21:22 from runway 24 at Edinburgh, with the co-pilot acting as the handling pilot.
After carrying out a standard instrument departure the crew climbed the aircraft to FL 230 at a speed of 170 kt with the autopilot engaged. As the aircraft levelled and accelerated through about 185 kt, the crew felt the aircraft roll to the left by about 5 to 10° and they noticed that the slip ball and rudder trim were both indicating fully right. The co-pilot disengaged the autopilot and applied right rudder in an attempt to correct the sideslip and applied aileron to correct the roll. He reported that the rudder felt unusually “spongy” and that the aircraft did not respond to his rudder inputs. Approximately 15° to 20° of right bank was required to hold a constant heading with the speed stabilised above 185 kt and a limited amount of aileron trim was applied to assist. Shortly after regaining directional control a FTL CTL caption appeared on the Crew Alert Panel (CAP) and the FLT CTL fault light illuminated on the overhead panel, indicating a fault with the rudder Travel Limitation Unit (TLU). The commander requested radar vectors from ATC for a return to Edinburgh, later declaring a PAN.

The crew carried out the required procedure from the Quick Reference Handbook (QRH). As part of the procedure they established that both Air Data Computers (ADC) were operating, before manually selecting the TLU switch to the LO SPD position. The aircraft had at this point temporarily slowed to below 180 kt. The co-pilot reported that on selection of LO SPD more roll control input was required to maintain heading and that roll authority to the right was further reduced. The commander therefore decided to return the TLU switch to AUTO and the required roll control input reduced. The green LO SPD indicator light did not illuminate.

An approach was made to runway 24, the aircraft was established on the ILS and was normally configured for a full flap landing. The crew added 10 kt to their approach speed, in accordance with the QRH. The co-pilot had to operate the control wheel with both hands in order to maintain directional control; the commander operated the power levers in the latter stages of the final approach. The co-pilot reported that the aircraft became slightly more difficult to control as the speed reduced, but remained controllable.

The aircraft landed just to the left of the runway centreline, whereupon the commander assumed control of the aircraft and applied reverse thrust. Despite the application of full right rudder pedal during the rollout, the aircraft diverged towards the left side of the runway. The commander re-established directional control using the steering wheel tiller. The aircraft was taxied clear of the runway and back to the engineering facility for inspection.

Th subsequent investigation and testing demonstrated that it is possible to incorrectly install the cams on the rear rudder quadrant shaft during maintenance. In this incident, the right hand cam was installed in the incorrect orientation and neither an independent inspection nor an operational test of the TLU system was performed. The incorrectly installed right hand cam was not detected prior to releasing the aircraft to service. When the TLU system automatically activated as the aircraft accelerated through 185 kt, the right hand roller encountered resistance as it came into contact with the upper lobe of the incorrectly installed cam, rather than slotting into the vee groove. This caused an uncommanded rudder input and associated control difficulties.

Three safety recommendations were made to the manufacturer, ATR.

The investigation is ongoing.

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Report: UK CAA publishes task forces’ recommendations on 7 top safety risks

March 28, 2011

The U.K. CAA launched a task force initiative in June 2009 to address the seven top safety risks.

The Paper pubsihed by the CAA consolidates the findings and recommendations of the task forces into one document.

The ‘Significant Seven’ safety risks cover:

  • loss of control;
  • runway overrun or excursion;
  • controlled flight into terrain (CFIT);
  • runway incursion and ground collision;
  • airborne conflict;
  • ground handling operations;
  • airborne and post-crash fire.

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

February 9, 2011

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.

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