(Please note, this matter is not currently being litigated in Australia)Despite seemingly endless news reports to the contrary, airline transportation is getting safer. In fact there has not been a safer time to fly.
The number of accidents in 2012, as that term is defined by the International Civil Aviation Organisation (ICAO) decreased by 21%, and the global accident rate decreased markedly to 3.2 accidents per million departures. This is a 10% decrease in fatalities, making 2012 one of the safest years on record.
For Nigeria, the 2013 ICAO Universal Safety Oversight Audit Report, which measures the air safety grade of a country based on its level of implementation of international rules, standards and recommended practices, found that country to have achieved effective implementation of international air safety oversight systems above the global average of 61%. It was one of only 16 African nations to achieve this.
Against this background of positive improvements worldwide, including regionally in Nigeria, fatal accidents are all the more tragic because they are, quite simply, unlikely to happen unless there is something substantially wrong with a safety system, a pilot, or the aircraft or its components (including engines and propellers).
Few aircraft simply fall out of the air – most accidents happen at or near runways. Engine performance is of most crucial importance during the takeoff and landing phases of flight, to ensure pilots have sufficient control to transition from ground to air or to ensure there is enough power in reserve to abort landings suddenly if needed. So latent defects or maintenance issues with powerplants are often magnified during these phases of flight. Propellers are the physical agents which convert the rotary motion of engines into the thrust required to move an aircraft through the air fast enough for it to develop lift. Any weakness in that chain of energy transfer can be fatal.
The domestic Associated Airlines Embraer 120 accident in Lagos, Nigeria on 3 October 2013 flight was a charter, and standards for safety could have been very different to international aviation. More likely than not though, given the type of accident this was, an EFATO, mechanical component issues may have been at play in the accident, and information on the past track record of Embraer 120 aircraft around the world would help inform that investigation inquiry in time. While only the Nigerian Accident Investigation Bureau (NAIB) investigation will properly determine the causes of that accident, the NAIB can be expected to examine the following selection of accident records which represent accidents during takeoff or landing and involved engine or propeller performance (or both).
An accident involving an Embraer 120 which was fitted with the same type of Pratt & Whitney engines as the Associated Airlines aircraft in Nigeria, was partially attributed by the US National Transportation Safety Board (NTSB) to deficient design of the propeller control unit. On 5 April 1991 Atlantic Southeast Airlines Flight 2311 crashed in Georgia in the United States during its landing approach. One of the causes of that accident which killed 23 passengers and crew, was propeller control failure. In that case the propeller was manufactured by a Connecticut propeller company known as Hamilton Standard.
Likewise, on 21 May, 1997, a SkyWest Airlines flight, Flight 724 – also an Embraer 120 - experienced a total loss of engine power on one engine with associated engine fire, followed by a total loss of all hydraulic systems after takeoff from San Diego, California. The aircraft suffered substantial damage but no one was injured.
Yet another accident happened in Darwin on 22 March, 2010 involving an Embraer 120 EFATO. In the Darwin instance this was a training exercise in asymmetric handling, ie, engine thrust was purposely pulled back on one of the two engines by the pilot to simulate an EFATO. However, during this exercise, partially due to increased pilot workload, but partially due to the fact that there was too much drag caused by the windmilling propeller of the engine which had had its power reduced, the aircraft banked sharply to one side and crashed, killing the occupants.
These non exhaustive examples are not enough to conclude that the Associated Airlines Embraer 120 aircraft suffered from some insidious known or unknown design defect. It is certainly therefore less than enough to conclude that there is some more general technical design or manufacturing issue with Embraer 120s overall, which issue has been responsible for the several accidents in the past.
However, given the prevalence of such aircraft all over the world in daily commercial transportation, including in Australian commercial charter operations, it would be prudent for investigators to consider whether the correlation between engine and propeller performance and landing or takeoff failures for this type of aircraft since its inception in 1985 has something to do with the tragic events in Lagos yesterday.
Update 22 October 2013: preliminary accident investigation reports describe that the right engine of the aircraft was producing less thrust than the left engine at take off. Also, an auto feather indication was made just prior to takeoff indicating that somehow the propeller blades had been in the wrong pitch (angle) for takeoff. A propeller was found feathered after the crash, which, raises the spectre of a propeller system design defect issue.
Shine Lawyers Aviation Department is investigating a similar scenario in relation to the Airlines PNG accident that occurred two years ago on 13 October 2011. The Associated Airline aircraft was found in the same state as the accident in PNG, and it could be argued for very similar reasons.
28 people died in the PNG accident, forcing the aircraft manufacturer to make significant modifications mandatory to prevent propellers being inadvertently or otherwise being put into the wrong pitch during flight - doing so, as likely happened in the PNG case - results in dangerous engine overspeed situations and potential engine failure.
Update 4 November 2013: The preliminary report by the Nigerian Accident Investigation Bureau (AIB), following initial assessment of both cockpit voice and flight data recorders, indicates the aircraft stalled shortly after takeoff, and that the pilots became aware, or already knew about, an aircraft engine control or engine propeller system fault when they commenced their take off roll. The continuing investigation will focus on the following, as described in the AIB preliminary report:
- Mechanical and electronic engine control issues related to the Right engine and Right engine propeller systems.
- Aural warnings related to auto-feather and the flap settings required for takeoff.
- Take-off configuration issues with respect to flap settings.
- Crew decision making and training with respect to proceeding with the flight despite concerns regarding the aircraft’s suitability for flight.
- When and how the number 2 engine fire handle was pulled.
- Standard operating procedures with respect to continuing the take-off roll despite continuous automated voice warnings of both ‘take-off flaps’ and ‘auto feather’ when there was ample time to abort the take-off.
- The airline management’s safety culture fostered throughout the airline.
Written by Shine Lawyers. Last modified: October 6, 2013.