GoAir passengers survived a wrong engine shutdown, where British Midland and TransAsia couldn’t

Go Air wrong engine shut down

Synopsis

The GoAir flight 338, an A320 was accelerating for takeoff on the runway on 21st Jun 2017 when the aircraft suffered a bird hit on Engine 2. The crew continued the takeoff but noticed abnormal sounds and vibrations. After takeoff the crew did not follow the documented procedure as a result identified the wrong engine and shut down Engine 1. The co-pilot read out N1 as ENG number 1, thereby giving incorrect input to the Captain. The aircraft climbed to 2500feet and soon the crew realized their mistake and attempted starting Engine 1. They failed to start in the first attempt and by the time the engine was eventually started, the aircraft had descended to 1800 feet and lost speed to a near stall when the Airbus stall protection feature, the alpha floor activated to prevent the impending stall. The aircraft landed safely, thereafter.

Go Air investigation report

Errors

Errors typically are defined as deviations from a criterion of accuracy. However, no clear standard of “correctness” may exist in naturalistic contexts. The “best” decision may not be well defined, as it often is in a highly structured laboratory task. Second, there is a loose coupling of event outcome and decision process, so that outcomes cannot be used as reliable indicators of the quality of the decision. Redundancies in the system can “save” a poor decision or error. Conversely, even the best decision may be overwhelmed by events over which the decision maker has no control, resulting in an undesirable outcome

Decision making

Intuitive decisions taken based on the famous concept of Thin Slicing (Gladwell,2005) help in faster decisions based on limited exposure. Sometimes it refers to using only a small slice of the available information for decision-making and ignoring the rest.At other times it implies compressing a great deal of information into a simple underlying pattern to be used in snap decision-making.The term is also used to refer to the simple underlying pattern itself and sometimes to the thin slice of time in which rapid cognition occurs. Thin slicing works well in day to day life when the risk levels are low, however when the risk is high, normative decisions and slowing down thinking (Kahnemann,2011) helps in cognitive ease and accuracy of actions.

Accidents

On the 8th Jan 1989, a British Midland B-737 was climbing through 28,300 feet when one blade of the fan in Engine 1 detached. This resulted in shuddering of the airframe, ingress of smoke in the cockpit and compressor stall of engine 1. The crew suspected that Engine 2 was the cause and shut down engine 2. Interestingly, the Engine 1 operated normally subsequently after the brief period of high vibration through descent towards the nearest airport.

The approach to the airport of intended landing was normal till the vibration started again resulting in engine fire and loss of power. Efforts to start engine 2 were not successful. The aircraft crashed before the runway.

Screen Shot 2019-02-22 at 11.21.16 AM
TransAsia_Flight_235_crash.png

The TransAsia ATR 72 was accelerating on the runway on 04th Feb 2015 when an intermittent signal discontinuity caused Engine 2 to auto feather. The propellers stop producing thrust any longer which is a feature to reduce drag from the propellers when an engine has failed. The crew did not reject and continued the takeoff. After takeoff the crew did not follow the documented procedure for identifying the engine and shut down the working Engine1. The aircraft suffered a series of STALL and crashed.

mindFly human factor analysis

Decisions in aviation typically are prompted by cues that signal an off-nominal condition that may require an adjustment of the planned course of action. Orasanu and Fischer (1997) described a decision process model for aviation that involves two components: situation assessment (SA) and choosing a course of action (CoA). In aviation, situation assessment involves defining the problem, as well as assessing the levels of risk associated with it and the amount of time available for solving it. Once the problem is defined, a course of action is chosen based on options available in the situation. Building on Rasmussen (1985), Orasanu and Fischer specified three types of option structures: rule-based, choice, and creative. All involve application of knowledge, but vary in the degree to which the response is determined.

Thus, there are two major ways in which error may arise. Pilots may (a) develop an incorrect interpretation of the situation, which leads to a poor decision an SA error, or (b) establish an accurate picture of the situation, but choose an inappropriate course of action a CoA error. Situation assessment errors can be of several types: cues may be misinterpreted, misdiagnosed, or ignored, resulting in a wrong picture of the problem; risk levels may be misassessed (Orasanu, Dismukes & Fischer, 1993); or the amount of available time may be misjudged (Orasanu Strauch, 1994). One problem is that when conditions change gradually, pilots may not update their situation models.

Pilots work under conditions of Divided Attention. When not able to devote all perceptual and decision making resources to one input or output on a continuous basis, attention can be divided; e.g., monitoring speed and attending to signals or directions at the same time. Under conditions of high stress and arousal, the scanning or sampling rate may increased but the pattern of scanning is reduced to a narrower range of inputs

Attention is restricted to the primary task

This can lead to important information being missed because the stress response caused attention to be restricted to the primary cause or a perceived primary aspect of the problem.

This effect is sometimes called ‘CONING OF ATTENTION’ or ‘NARROWING OF ATTENTION’

Therefore it important that when a critical decision like shutting down an engine is required to be taken, the crew must reduce stress and slowdown. This helps to increase  the scan area and proper identification and fault analysis leading to a safe outcome.

 

14 Comments on “GoAir passengers survived a wrong engine shutdown, where British Midland and TransAsia couldn’t

  1. In the case of 4th generation airliners like the Airbus A320 family …the high level of automation actually allows quite a lot of “spare mental processing capacity “ to be available even in abnormal situations.The existing training regime actually covers situations like engine failure/damage during takeoff regularly during Simulator recurrent training.So in my opinion what is required is a change in focus to broaden the understanding of the few primary issues common to most engine failures of this generation of jet engines and the documented consequences (shades of Evidence Based Training?) so that Pilots have a realistic appreciation of the length of time available for decision making.
    Also the need to demonstrate and practice…using all available automation to reduce work load …so that adequate mental processing capacity of both pilots is brought to bear in the identification and decision making process.

     
    • Teaching automation is another part of the puzzle. The rate at which pilots are trained, conceptual knowledge is extremely weak. The co-pilot of Go Air had all the time in the world to identify the parameter out of limit but due to a knowledge-based error in identifying the engine, he called out the wrong engine. VIB N1 was identified and called out as Number 1(engine). The crux is that an engine should be shut down only if a procedure tells you to do so. In this case, the procedure required, bringing the affected engine thrust back to get the VIB parameter below the advisory level.

       
    • As per procedure there is a standard followed in most of the airlines in which the pilot flying always confirms from the pilot monitoring before taking action on the thrust levers not sure what happened in this case.

       
    • Ivan what you are talking is book but in this particular incidence P1 has lost his job but P2 switched over to Indigo. What corrective training was recommended by DGCA and what has been done? Further I will like like to know who was his trainer what was his comments and what recommendation has been done against that trainer? Further in Indigo who did his assessment? It is not out of place to mention being dgca person do you have such authorisation if no then withdraw it.

       
      • The investigation has been conducted into the air turn back after a bird hit with a single man conducting the investigation. It is not even a serious incident and human factors has not been considered. Why has it been downplayed?

         
  2. As per procedure there is a standard followed in most of the airlines in which the pilot flying always confirms from the pilot monitoring before taking action on the thrust levers not sure what happened in this case.

     
    • The Copilot called out ENG1 after reading N1 on the vibration. The procedure was not read out, which calls only for thrust to be reduced to get the parameter within the limit. It doesn’t call for an ENG shut down in air.

       
  3. Atul,
    Going by the basic tenets of SMS (Safety Management System )…we need to evolve from the “punitive action “ mentality against individuals.
    What needs to be done is analysis of the root Human Factors causes and devise systematic responses.
    Just like the evolution of the procedure where an unstabilised approach requires an initiation of a go around by the Pilot Monitoring (after 2 calls,generally).Evantully we will need to address other situations where an intervention by the Pilot Monitoring might be called for.
    In this context I can only reiterate the importance of adopting EBT( Evidence Based Training) at the earliest .(And a basic recognition of EBT as an acceptable checking/training program by DGCA)
    It will lead to the identification of and focus training on the Requisite Competencies and development of HOTS (High Order Thinking 🤔 Skills )…which is the basis of TEM (threat and error management)
    This approach would have identified and corrected the communication issues the First Officer had ( by incorrectly verbalising N1 as Eng 1)
    The Captain’s conceptual knowledge base inadequacy of modern jet engine failures compared to the older generation turboprops and jets he had flown earlier…should also have been detected and addressed by a well developed EBT training program.

     
    • If we discuss the grading levels, HOTS is demonstrated by a person who is Proficient and beyond i.e. Expert. A competent person is one who can apply SOP’s and manage the flight but if the environment changes, the outcome may also change. A Competent person has conceptual knowledge and is able to apply learning to different environments. Therefore, EBT in its present state might not be the best concept. The element of unexpected event and surprise elements in training can ensure that the learning has been internalised. Therefore, I feel that a need analysis is required prior to adopting a training methodology. Just a though.

       
  4. The present training and checking regime (as required by existing regulations) leaves a significant part of the “knowledge and expertise” transfer and evaluation to application of “pre-established “ Procedures …and the experience and expertise of the trainers (and checkers are now actually discouraged from playing a training role)
    Obviously this is not good enough …to ensure 100% safety.
    The NTSB (And FAA) have determined (from accident evidence based data )that the ultimate reason for crew error related accidents have one common thread …lack of HOTS .
    While this has been known for a while… the older generations of aircraft,typically required a substantial proportion of the pilots “mental processing capacity “in just flying the aircraft and applying procedures from rote learning.
    So focus of training has traditionally been on the 2 Competencies of “aircraft handling “ and “ technical knowledge “.
    So while the need to develop the other 6 Competencies has always been there…the older technology did not free up enough mental capacity to allow them to be meaningfully trained for or assessed .(These Competencies have so far been developed by “most”individuals ….on their own “intuitively” as they gained experience…and/or assisted by coming across good instructors )
    New technology (with consistently reliable automation)is finally allowing the freeing up mental processing capacity to allow the human mind to do what it does best….not memorise but analyse….i.e. detect threats and respond (using skill /rule/conceptual knowledge ..based decision making)
    Most experienced trainers on 4th generation aircraft are aware of this potential…and instinctively use the opportunity to focus training on these…so far neglected but equally critical to safety …Competencies.
    Competencies based training is an essential element of Evidence Based Training.So to that extent a gradual transition is inevitable and recognised as such by ICAO .
    I feel it is entirely possible to ensure the existing minimum checking standards and actually add to them by gradually adding layers of EBT (as proposed by individual operators…based on their level of expertise and technology)
    Having been involved with the “standardisation” of the most experienced training Capts in our industry on 4th generation aircraft for the last so many years…I know a lot of them share my assessment of the likely effectiveness of EBT .
    BTW there is a group on Competencies which apply to Instructors too …which would help in the assessment and implementation of this training program.

     
      • Thanks, I have read it. Am writing another blog. By the way I have been speaking on HOTS for about 5 years at International Training Seminars. It is a subset of the learning pyramid by Bloom.

         
  5. Looking forward to reading your next blog.
    It’s high time we allowed operators with the required expertise and inclination ..to evolve their training methodology to both keep up with,and take advantage of rapid improvements in technology and understanding of human behaviour.

     

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