Aircraft accident investigation is normally conducted by a body mandated by law in a country to conduct investigations into aviation mishaps.
The investigation is normally not to place blame or punish individuals or organizations involved but to make recommendations to prevent future recurrences of the same problem. We do not punish because we want to encourage individuals involved in the accident to speak the truth.
Any aircraft system normally has a redundancy, that is every system is normally doubled. Engines are either two, four etc, hence it is very rare for the hardware or aircraft to fail. Human error is a causal factor in about 80-90% of aviation mishaps and is present in another 50 to 60 % of aviation accidents. The process of mishap investigations is difficult, time-consuming and may take years but very satisfying when we as flight surgeons know that our contributions will help improve flight safety.
It has been established that accidents are rarely caused by a single factor on an individual but a myriad of inherent failures or conditions as reported by Shappell. The accident investigation is to understand how these latent failures occurred and to prevent these from happening again.
In this write-up, I will l attempt to give you a summary of the steps involved in aircraft accident investigations and apply it to the Starbow flight S9-104 incident.
The accident investigator is interested in how to identify the latent and active failures or conditions that may occur in complex systems. An internationally recognized way to do this is the Reason or Swiss Cheese Model and this describes the levels at which active and latent failures occur in complex operations as in aviation.
The levels of Reason model are:
Based on Reason’s cheese and Shappell models, the Department of Defense (DoD) of the United States developed a taxonomy to identify hazards and risk called DoD Human Factors Analysis and Classification System (HFACS). HFACS entails four main tiers of human errors:
Acts, Preconditions, Supervision and Organizational influences.
Acts are the factors that are closely related to the accident and are described as active failures or actions committed by the operator that resulted in the human error or unsafe situation. Active failures are identified as errors and violations.
Errors are factors in accidents when mental or physical activities of the crew fail to achieve their desired outcome as a result of skilled, perception, judgment and decision making errors. Errors are unintentional.
Violations are factors in an accident when the actions of the crew represent a willful disregard for rules and instructions and lead to an unsafe situation. Violations are intentional.
Preconditions: preconditions are factors in an accident if active and/or latent preconditions such as conditions of the operators, environmental or personal factors. Environmental factors include Physical environment and Technological environment.
Physical environment like weather, climate, harmattan etc
Technological environment factors in an accident are when cockpit workspace, design factors or automation affect actions of individual and result in human error.
The condition of the individual is psycho-behavioral, adverse state or physical/ mental limitations for example inattention and distraction.
Personal factors are self-imposed stress, for example, drinking alcohol or operating under the influence of illicit drugs.
An accident event can often be traced back to the supervisory chain of command. There are four major categories of unsafe supervision: Inadequate supervision, planned inappropriate operations, failure to correct a known problem and supervisory violations.
Inadequate supervisions are supervisor or oversight inadequacy, local training issues, and lack of feedback.
Planned inappropriate operation: crew makeup composition, proficiency, authorized unnecessary hazard.
Failure to correct a known problem: personnel management and operation management
Supervisory violations: discipline enforcement, directive violation, and currency
Organizational influences: This refers to poor decisions of upper-level management which directly affect supervisory practices. These latent conditions generally involve issues related to resource acquisition management, organizational climate, and organizational processes.
I will now place the events leading to the Starbow accident to the above model.
On November 25, 2017, the media in Ghana reported that a Starbow airline aircraft ATR72-500 (note the aircraft model number) carrying 63 passengers and 5 crew overshot the runway and ended up in the fence of the airport.
Eyewitness and passengers blamed the accident on heavy rain and in their opinion, the pilot should not have taken off. In aviation accident investigations eyewitness reports are not always reliable, this was proven in a research among A-level students in the UK. Rainfall does not interfere with operations of an aircraft per se, its often rainstorms that are the problem.
When the cross-wind speed is about 30knots (56km/h) and over during takeoff, the take-off needs to be aborted and all pilots know this. Was there a crosswind of more than 56km/h that day?
On Tuesday, February 26, 2018, the Minister for Aviation briefed parliament that the accident was caused by loss of situational awareness and failure of the cockpit crew to execute the correct procedures in aborting the take-off. She continued and I quote "During the take-off run, the aircraft gradually drifted the runway without the crew appreciating it as a result of the severity of the weather. In the process, the captain's seat inadvertently moved rearward, which made the captain transfer control of the aircraft to the co-pilot. At that point, the aircraft was virtually off the runway,"
Unquote: This was reported in the 28 February edition of Daily Graphic online.
The unsafe acts here are a procedural error that is the procedure in undertaking the change of controls from the pilot to the copilot, checklist error, judgment and decision making error.
Conditions of the pilots include inattention, and distraction; situations like this increased workload.
Personal factors. Communication between the crew; this is where the Crew Resource Management (CRM) applies. CRM in layman language simply means unhindered communication between the pilot and copilot. In some cultures like ours and persons of Middle Eastern and Asian origins, a junior is reluctant to correct his superior when he makes a mistake because he fears he will be rebuked. This is call authority gradient in the cockpit. This is dangerous in aviation operations and is discouraged.
Supervision: The Ghana Civil Aviation Authority has oversight responsibility of all the domestic airlines operating in the country. On 30th December 2016, European Aviation Safety Agency (EASA) issued an airworthiness directive number 2016-0256 which states that: Occurrences have been reported of pilot/ co-pilot unexpected seat rearward movement during take- off and landing. Investigations determined that horizontal guide block wear, the presence of burrs on horizontal center track, and horizont al track-lock system weakness (spring tension too low) were various causes which contributed to the seat not being correctly locked. This condition if not corrected could lead to further cases of unwanted flight crew seat movement, possibly resulting in reduced control of the airplane.
These seats are known to be installed on, but not limited to ATR-G 42, and ATR 72. This aircraft model is the same type that Starbow operated. Did the GCAA know of this airworthiness directive? And if they knew did they enforce or make sure Starbow complied with the directive?
The remuneration policy of the airline, is it that the crew only get paid when they fly and hence the pilot may have tried to fly that day at all cost?
In a nutshell, this accident that occurred on November 25, 2017, actually started showing its heard from December 2016 when the Ghana Civil Aviation Authority (GCAA) may have failed to notify Starbow of the EASA airworthiness directive or enforce the directive to ensure that the unexpected movement of the pilot seat of this aircraft was fixed.
This analysis demonstrates how aviation accidents are a result of a myriad of failures from organizational to the individual level.
In conclusion, latent or active failures that may cause aircraft accidents in this country could be from the hardware (aircraft), the GCAA, the airline company, air traffic controllers and the crew; hence an independent body mandated by law needs to be set up by the government to be responsible for air accident investigations in this country.
The current law that mandates the aviation minister to constitute a committee to investigate aircraft mishaps needs to be amended. This is the standard practice as it is with the National Transportation Safety Board (NTSB) of the US and the Air Accident Investigation Branch (AAIB) of the UK. conduct aircraft accident investigations. The GCAA’s role is to implement the recommendations of the investigative body.
The writer is a flight surgeon