Focussed Flying-A moment to think can make a difference
By Johan Lottering
SOME pilots are always in a hurry. The better we are the more we tend to optimise. Priming both engines at the same time before start in smaller piston twins is one way of showing (ourselves) how adept we are. Sometimes we have to learn how to fit in those seemingly unnecessary though vital steps in between. A friend with a twin Comanche had once discovered, much to his alarm, that the fuel lines had been inadvertently swopped around during a routine service. It could have been disastrous as he had been taught to use the fuel flow indications to identify the inoperative engine during asymmetric operations.
The crucial steps of not only confirming the inoperative side, but identifying the kind of problem correctly before selecting the proper course of action, have saved many lives. Some students are readily confused by the 'dead leg, dead engine scenario'. I have found many cope far better if prompted to 'step into the live' and at the same time anticipating the drag and hence combined and yawing tendencies towards the inoperative side.
Paying attention to corresponding factors such as no change in sound or yawing moment upon retarding the throttle prior to shutting down or feathering the affected engine can make the difference between life and death. Single-engine pilots can learn from this approach too. Several cases are on record of especially heavily loaded six-seat aircraft crashing and burning due to mere system failures. The failure of an engine driven fuel pump or turbocharger can sometimes be overcome by retarding the throttle and switching on the electrical fuel pump.
Incorrectly identifying the respective operative and inoperative engine in asymmetric operations has been the demise of many. The woeful cry of Capt. Liao Jian-zong (41), "Wow, pulled back the wrong side throttle" after an engine flame-out on February 4, 2015 may date back to failed upgrading attempts as commander of an ATR 72-600 eight months before. When TransAsia Airlines Flight 235 went into the Keelung River minutes after taking off from Taipei's Songshan Airport on a flight to Kinmen Island claiming 43 aboard it may have been no surprise to assessors. Upon passing their protégé on a second attempt, it was not without reservations. Comments included "being prone to oral errors", "a tendency not to complete procedures and checks" and "inadequate cockpit management and flight planning".
The disaster in Taipei revealed striking similarities with the Jetstream 41 accident on September 24, 2015. The South African regional airliner had gone down shortly after departure from Durban International Airport during a positioning flight to Pietermaritzburg. The 40-year old captain had 276 fewer hours on type than his rather youthful co-pilot who had tried prompting him to do the right thing. To her surprise he had responded by incorrectly pulling the operative left hand engine's condition lever into feather cut-off. According to the SACAA report no. 8692 she had not only identified the inoperative engine correctly shortly before, but even announced the kind of warning, being oil contamination failure. She could also be heard prompting him to retract the gear on the CVR. The action would have reduced drag and improved the probability of flying on the operative engine.
Under prevailing environmental and operational conditions they were 2646 kg lighter than the maximum needed to climb to the required 1500 feet above ground before returning to land with one engine. The CVR also highlights that the captain's situational awareness had been lagging behind the co-pilot, to the point of getting his tenses mixed up, responding first: "We have lost an engine" and then "We are losing an engine". In response the co-pilot advised him "I have it, I have it… keeping runway track six thousand feet… flap is zero. We have lost an engine". A linguist may well explain how she, having already identified and assessed the situation correctly, had regressed or reverted to his level of awareness to reduce the potential for conflict and confusion, creating a new basis from which to progress.
She may well have been as surprised as the two Swiss ladies who had ended up in the passage of the suburban home near Virginia Airport on August 22, 2005. On that occasion with the same captain behind the yoke and only one of the two engines of the ten-seat Britten Norman BN2B Islander operating, he had also lost it. The one engine had quit due to suspected carburettor icing, a condition readily remedied.
Fortunately the elderly home owner had been absent at the time, as were the pupils of the Meredith Secondary School on Heritage Day 2009, where the Jetstream 41 would later en up. The Jetstream 41's right-hand engine's second stage turbine seal had broken, as similar seals had done on two occasions in similar aircraft preceding the issuing of a service bulletin and seven afterwards.
Especially in the case of the Islander one could have asked why it had proven impossible for the pilot to continue flying with one engine inoperative. Those with hindsight admittedly have perfect vision, but BN2A rated instructors may well attest to the relative ease with which those docile beasts are handled on one engine. The single engine minimum control speed (Vmc) can be as low as 51 miles per hour.
Our cue is to revert to original twin flying training techniques, as was one of the recommendations by the SACAA after the Jetstream 41 accident. The imperative of correctly identifying the inoperative engine at first glance seems overstating the obvious. The track-record shows otherwise.
In the British Midlands Boeing 737-400 air disaster of January 8, 1989 the captain had incorrectly used fuel flows to identify the inoperative engine on a flight from Heathrow to Belfast. A fan blade had detached causing severe vibrations and engine smoke. The first officer added to the confusion by incorrectly identifying the right-hand engine. His convictions were exacerbated by smoke from the entering the forward cabin.
In previous versions of the Boeing 737 the left engine had supplied the flight deck with compressed air and the right engine the cabin. With the 400 version the left pack fed both the flight deck and aft cabin zone. The right engine fed the forward cabin. Smoke in the cabin had led them to incorrectly assuming the right engine being the culprit. When the pilots subsequently shut down the right engine the amount of smoke dissipated.
Coincidentally the auto-throttle which had been disengaged before shutting down the right engine, had led reduced fuel flow to the affected left-hand engine less fuel being ignited in the exhaust trail. The LED displays on the vibration indicators had been changed. The needle had gone around the outside of the much smaller gauges, instead of on the inside. Furthermore, vibration indicators were considered unreliable at the time. The result was 47 dead when the aircraft crashed near Kegworth.
Knowing those intricacies are vitally important. Fly safely!
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