SACAA synopsis reference: CA 18/2/3/8858
On 26 October 2010 at approximately 1530Z two aircraft, a Piper PA-28-180, registration ZS-KIN and a Jabiru, ZU-BXA were conducting circuit training at Wonderboom Aerodrome (FAWB). Runway 29 was in use and right-hand circuits were flown. The Jabiru was being flown by an instructor pilot and a qualified pilot on a revalidation checkflight whilst the Piper was flown solo by a student pilot. The student pilot had previously conducted three circuits with an instructor pilot onboard and, following those circuits, the instructor pilot assessed the student pilot as being at a standard that would allow him to conduct further solo circuits.
That required a full stop landing for the instructor pilot to exit the aircraft. After the flight instructor had disembarked from the aircraft, the student pilot took-off and re-entered the circuit to conduct solo circuit training. The total circuit traffic at the time the student pilot re-entered the circuit was seven aircraft.
Sometime later, ZU-BXA was cleared on final approach for a touch-and-go landing onto Runway 29 at FAWB. The aircraft ZS-KIN, which was on a base leg for a touch-andgo landing Runway 29 was cleared, after he confirmed he had the Jabiru in sight, he was instructed to position himself behind the Jabiru and was number two on final approach for a touch-and-go landing. Shortly after ZU-BXA became airborne following the touch-and-go landing, the two aircraft ZS-KIN and ZU-BXA collided, approximately 30 feet above the runway. The pilots of both aircraft lost control of their respective aircraft and impacted with the ground. Both aircraft were substantially damaged during the sequence of the accident. The flight instructor onboard ZU-BXA was seriously injured during the sequence of the accident. The private pilot under instruction in ZU-BXA as well as the student pilot flying ZS-KIN sustained minor injuries.
• Failure by the student pilot flying ZS-KIN to execute an immediate go-around as instructed by ATC.
• ATC had to call the aircraft ZS-KIN three times before the pilot acknowledged during a critical phase of the flight.
• Instructions by ATC to the aircraft ZS-KIN to execute an immediate go-around was not assertive enough for the student pilot to react.
• The AT Chad been operating in a high workload environment in the period leading up to the mid-air collision (only one ATC in the tower).
• The student pilot of ZS-KIN did not see ZU-BXA in time to prevent the collision (loss of situational awareness).
• Neither pilot in ZU-BXA saw ZS-KIN in sufficient time to avoid the collision.
• The decision by the aviation training organisation (ATO) to send the student pilot in ZS-KIN solo during a busy traffic period should be regarded as a significant contributory factor to this accident as it placed the student in a high workload environment whereby, he lost situational awareness. (Disregard for standard/safe operating procedures as contained in the ATO operations manual).
• The student pilot of ZS-KIN had a low level of experience.
Comments by Charlie Marais
The investigated facts of any situation are tangible, neatly presented in an orderly and chronological sequence, with just enough emphasis on those facts that will tick the logic box. Far be it that I would try and rehash the accident report or to try and uncover the genie in the box. That we must learn from the experiences of others, is paramount to improving aviation safety. This accident led to many tears and sorrows and had an everlasting effect on those involved. Throughout the legal actions and investigation interrogations, reliving the moment and the prior and consequent moments, must have been reigniting a nightmare for all involved. It has been a long time and my intention is to have a closer look at human factors that were at play.
The term ‘human factors’ is not a one-liner definition kind of principle, so I will do a basic overview of the concept and then discuss how it affects decision making, conscious or subconscious behaviour. The definition I like most: “Human factors are those factors limiting man’s ability to be perfect in thought and deed.” When man started interacting with technology, the gaps in man’s make-up were revealed and during the industrial revolution, the man and machine interface showed many flaws, leading to the concept of ergonomics. The machine or technology had to be altered to compensate for the shortcomings in man’s design. This helped, but the complexity of human behaviour, did not end with physical interaction, the world also became congested by stimuli as technology advanced.
Decision making became complex as more inputs fought for preferential position in the human cognitive processing. I want to state that I do not believe that choice or free will was an option during the making of this accident. Philosophers have more and more consensus over the non-existence of free will. I have no intention to debate this concept, but to show how intricate our reality is, when considering factors such as knowledge, skills and experience, mingled with conscious awareness, sub-conscious awareness, emotional response to adverse conditions, to mention but a few. Okay, I am not going soft on anyone and I am definitely not trying to absolve any person from responsibility and probable accountability.
The sortie of training in the circuit was nothing unusual to me as the student managed height and heading for the first time, probably to the surprise of both of us. Left hand downwind for runway 01 at Tempe airport, settled at 5500 feet on local pressure (QNH), and in the process of doing downwind or pre-landing procedures after the call on the airfield frequency 131,3 Mhz. I was scanning to the left of the aircraft nose to ascertain our position relative to the runway when my vision was filled with another aircraft flashing past from our 10 o’clock position. Flying a Cessna 172, a high wing design, it was not possible to see above the aircraft and for this other aircraft to fill my vision, it had to be low enough to see and close enough to create quite a stir in our cockpit.
The other aircraft, a PA28-140, a low wing aircraft, also only saw us when our paths crossed with him being around two meters above our flight path. When on the ground, I looked all over the airfield to find the aircraft and I found it shut down in front of an out of normal view entrance to an AMO.
I was ready to fight. The elderly gentleman that walked towards me started apologising before my mouth opened. He did not know the Tempe frequency and his friend just asked him to deliver the aircraft for a service, he was deeply sorry and was now seeing the error of his ways. I managed a stutter something to the effect that all of us could now have been dead, to which he agreed without any argument, but offered another apology. I then noticed his pants vibrating. His legs were shaking from the adrenalin overdose reaction during this withdrawal period. Strangely the thought that struck me was how did he get his aircraft on the ground in one piece shaking like that. During the next ten minutes I realised that this pilot was a genuinely nice person, even though part of me wanted him to be exposed to a short-lived near-death experience.
In the case of the aircraft colliding just above the runway at the Wonderboom airfield, my first comment would be that this kind of accident has been years in the making and similar accidents or even incidents from that time on, showed the same ingredients. The following is still in existence namely, overcrowded air space on and around Wonderboom, the mixture of ab-initio training, charter and at times scheduled flights, understaffed ATC, visiting aircraft joining from various points and a totally overcrowded frequency. There are more, but these will do for now.
Now we introduce language into this pot with vastly differing aircraft approach speeds and to boot high and low wing aircraft, brewing a bitter stew of unpredictable safety outcome. Yes, I am sure you did not want to hear this one. Just stand back and listen, observe and connect the dots. It would now be a lot easier to think of the humans and their omniscient capability. The stress of controlling a circuit with many random variables, of being in a congested circuit and the difficulty of getting to join during peak times are but a few to focus the argument. It only needs one pilot to close-up during an anxiety flush and the rhythm of this highly dynamic churning space is disrupted. This was the case, because the student froze and no one could gently shake him out of his trance. The ATC and whoever had the means to communicate with him, could not project that in the final few seconds preceding the accident, that the accident was a clear probability. The student on final no 2 could not see no 1 and those that could, either did not look and if they did, did not act assertive enough.
The reasoning after the facts of the accident is relatively easy and probably almost perfect in hindsight. To find responsibility is to a degree possible, but not conclusive to the avoidance of the actual accident. The question could be posed to who had, during the various stages, the bolt-cutter to break the error chain that was developing. In all situations there is the perfect script, if not followed exactly will lead to deviances. If the deviances are not observed, there is no way to stop any continuance of the deviance. Once the deviation matured to an upset situation, how to recover from this unwanted state becomes important. Working back in this sequence, the first remedy is to become aware of the deviation from the norm. Without awareness, there cannot be any conscious remedial action. Should this phase slip through the cracks, the next important stage would be to recognise the upset stage that the aircraft is in. With all the skills in the world to recover, it all would be a waste if the pilot did not know corrective action was needed. So, we start with knowledge of the correct process and procedures attached, coupled with how visual cues would enable one to judge the present status. Then we teach how to scan to look for deviations and once the deviation is observed, how to correct the deviance to regain the norm. We then go a step further and teach how to recover when the deviance results in an unwanted upset. All of the stages mentioned are subject to the ability of the pilot to become aware and then to have the capability to react, which is subject to the pilot’s physical and mental condition.
The report mentioned that the ATC issued an immediate go-around. Well, not so. Rather the words of “.... go around now please.” was uttered. Hardly the phraseology that would pierce my mesmerised state of accepting my version of reality. What I perceive to be at any time is my reality and this state will linger until I am convinced otherwise by logic or by force. The only way to get through a person’s haze of reality is to speak up, load and clear and even forceful when needed to avoid misunderstanding, or lack of timeous response as required by the controller.
My stress levels would go through the roof if I had lost the bigger picture, I struggle to understand instructions, not just due to language barriers, but enhanced through stress increase and the overflow of audio input.
I must react, but I cannot make sense and thus become incapacitated with indecision due to the body’s natural reaction of fight or flight, as managed by the part of the brain called the amygdala. Naturally, I am sketching what contributes to us being less capable under high stress situations as can be gleaned from the stimulus/ performance graph.
Stimulus and stress could be used in the same sentence when measured against performance. In short, as stimulus or stress increases above the optimal value, performance deteriorates and we eventually become onlookers into our world of perceived reality, unable to intervene.
The main task of training, after the basic skills are conquered, is to train repetition in actions normal and emergency. It is like a drumbeat. You want this, you see this, you do this and so on. Recovery or emergency procedures are trained with the intent to form subconscious reactive behaviour.
This could be extremely dangerous if you should teach or allow incorrect procedural steps to settle in the student’s subconscious, the candidate will react automatically as taught. Any recovery technique such as from a stall, a spin, lost on navigation or a go-around due to external or internal triggering, must be settled in cement. Your habits are cemented parts of your subconscious and free will is not on the menu. As time is exponentially constrained, the ability to have conscious decision-making fades with subconscious behaviour taking the lead.
Given the airspace under discussion, the preparedness of the student or even qualified pilots, not well exposed to such intense traffic, must be guaranteed to a tolerable level as per International Civil Aviation Organisation (ICAO) risk management criteria.
All that this means is that we are not perfect, but we can allow some deviances, but within predetermined parameters. Thus, the decision to wean the student into a packed circuit, by starting with low traffic congested circuits when building confidence, is a good idea. There is a reason why testing officers limits students from time to time, but you must take the time to read the reports and to be aware of any limitation that was placed on a candidate. Internal flight school communication would help to avoid these traps.
Ten knots on final approach speed more than no 1 in a circuit is looking for trouble. In this case the candidate slowed down to a minimum, but it was still not enough. Running in slow and between traffic, it is not inconceivable to find stress at extremely high levels. The chain of events of non-interventions as well as interventions proves once again that we as pilots need external support. In this case the pilot was totally green, not circuit solo fit and ATC knew that. ATC must look after us, not just speak to us.
Instructors must always decide on what is best for the student and if the instructor decided that the student is ready, this must first be checked with those that restricted the student for starters, unless you are a higher-grade instructor that was entrusted with this decision.
The split between ground and air traffic frequencies would never be the total solution for this problem, but for starters ease the ATC controlling the entire air space and runway. Wonderboom airport is a fine facility, but proper risk management must be undertaken by external professionals, consulting with all stakeholders.
Will you be able to make flying risk free?
I dare to say not, but then we must hone our environment to a tolerable level and not textbook acceptable. If flying were ever a choice between acceptable and not acceptable, no-one would have flown.
The actual act of flying is operationally minded and therefore the word or concept of tolerability was inserted in the risk management process. Flying is not a perfect skill, but one that is considered within tolerances to compensate for the human factor of inconsistency.
A reminder that as normal pilots make mistakes, student pilots make infinitely more and are expected to make the mistakes. Our challenge is to train to a standard that can ensure reasonable safety, especially whilst operating in a busy circuit.