The pilot of a Sikorsky S76 helicopter was left with only lateral cyclic control when a loose screw lodged at the base of the cyclic stick. During transition from normal cruise flight to the approach to land the pilot found that the cyclic could not be moved aft. He also found that with any further forward movement of the cyclic stick it could not be moved aft of the new position. The pilot froze the cyclic longitudinal position and the helicopter stabilised in a level pitch attitude at about 85 knots indicated airspeed. Using only lateral cyclic movements to manoeuvre the helicopter, the…

In 1991 ATSB's predecessor (BASI) published a research report titled Limitations of the See-and-Avoid Principle. This report concluded that 'the see-and-avoid principle in the absence of traffic alerts is subject to serious limitations'. Unalerted see and avoid has a 'limited place as a last resort means of traffic separation at low closing speeds' and is 'completely unsuitable as a primary traffic separation method for scheduled services'. Nevertheless, operations in a number of types of airspace currently require the application of see-and-avoid techniques by the pilots of both visual…

The Avgas contamination event that happened over Christmas 1999 caught everyone by surprise. It had not been seriously considered as a potential hazard to aviation anywhere in the world, therefore the consequences had not been considered. The reasons behind why the fuel became contaminated were unexpected. Mike Watson, one of a team of transport safety investigators who had the task of sifting through an overwhelming amount of data and publishing the final report, gives some insight. No one was hurt as a result of contaminated aviation fuel, and there were no accidents that could be…

There has been an aircraft accident. Debris from the wreckage is scattered throughout a 200-metre radius. Tragically, the aircrafts crew and its passengers have been fatally injured. The sound of sirens permeates the scene as police and ambulance services attend. Soon, media representatives arrive to speculate as to its causes with cameras poised to document the wreckage. That this could happen so suddenly and wreak such devastation strikes at the heart of many people. An occurrence like this is always associated with a sense of urgency to understand its underlying features. But aircraft…

The ATSB collects and analyses data from accidents and incidents involving aircrew, ground personnel and passenger safety. In this issue of the ATSB Supplement, a selection of Australian cabin safety occurrence briefs are summarised and one from the Transportation Safety Board of Canada. Photographs of the burnt out Saudi Arabian Airlines Lockheed Tristar at Riyadh on 19 August 1980 following an emergency landing. All 287 passengers and 14 crew on board died from smoke inhalation from a fire in the aft cargo hold which started shortly after take-off. Despite the successful landing the crew…

In Australia, mountain waves are commonly experienced over and to the lee of mountain ranges in the south-east of the continent. They often appear in the strong westerly wind flows on the east coast in late winter and early spring. Mountain waves are a different phenomena to the mechanical turbulence found in the lee of mountain ranges and can exist as a smooth undulating airflow or may contain clear air turbulence in the form of breaking waves and 'rotors'. Mountain waves are defined as 'severe' when the associated downdrafts exceed 600 ft/min and/or severe turbulence is observed or forecast…

The final report of the accident involving Qantas B747-400 VH-OJH at Bangkok, Thailand on 23 September 1999 concluded our most important investigation of an accident involving an Australian registered jet aircraft. The investigation was one of the most comprehensive and exhaustive ever conducted by the ATSB (or its predecessor the BASI). Investigator In Charge, Mike Cavanagh, reports on the investigation itself. The Australian Transport Safety Bureau released its report on the Qantas B747-400 runway overrun accident at Bangkok International Airport on 23 September 1999 on 25 April 2001…

ATSB's air safety investigator, Mike Watson, in his unique style, discusses the insidious dangers of carburettor icing. The aircraft was on short final for runway 29L when the pilot made a brief Mayday call. The aircraft was then observed to land in a car-yard, short of the runway. Both occupants managed to evacuate without injury. The pilot later reported that the engine did not respond when an increase in RPM was required, as the aircraft was undershooting the approach. The aircraft subsequently collided with a fence, short of the runway. Weather conditions at the time were conducive to…

With the development of airborne collision avoidance systems (ACAS) and their fitment in aircraft since the mid-nineties it has become possible for pilots to know if their aircraft is on a collision course with another. When an ACAS warning is received the pilot or crew has time to take avoiding action. Some of the systems fitted in aircraft today will advise what to do - climb or descend away from a conflicting aircraft. Future developments will also give turn advice. The effectiveness of ACAS is totally dependent on the presence of an operating Mode C or Mode S (altitude encoding)…

A significant proportion of all occurrences reported to the Australian Transport Safety Bureau (ATSB) involve aircraft striking wildlife, especially birds. This report provides aviation birdstrike and animal strike occurrence data for the period 1 January 2002 to 31 December 2009. It also describes the results of an ATSB survey of aerodromes concerning current wildlife control measures. Reported birdstrikes have been generally increasing since 2002. In 2009, there were 1,340 birdstrikes reported to the ATSB. For high-capacity aircraft operations, reported birdstrikes have doubled from 2002 to…