Safety Accident Analysis
Right attitude?
A quick look at the National Transportation Safety Board (NTSB) database in the USA suggests that in 2018, Loss of Control (LOC) accounted for over 200 in-flight accidents of which over 50% involved at least one fatality. A closer examination suggests it may be time to get back to basics, as Steve Ayres reports…
Accident 1
Security camera video captured the aeroplane during the initial climb after take-off. The video showed that as the aeroplane entered the view of the camera, it appeared to be in a shallow climb. However, about 14 seconds later, the aeroplane descended in a near vertical manner, out of view of the camera. The aeroplane impacted open terrain about 1,850ft west of the departure end of the runway. Examination of the airframe revealed no mechanical anomalies that would have precluded normal operation, however, the left fuel selector valve was in the left wingtip tank position, and the right selector valve was in a position between the right main fuel tank and right wingtip tank position. The Aeroplane Flight Manual Supplement for the wingtip fuel tank installation stated that the wingtip tank fuel was to be used in level flight only. It is likely that because of the placement of the fuel port in the wingtip fuel tanks, when the aeroplane was in a climb
attitude, that the fuel may not have reached the fuel port in the tank. As a result, the pilot’s improper positioning of the fuel valves could have led to fuel starvation during the take-off climb and resulted in a loss of engine power. It is likely that the pilot experienced a loss of engine power, to some degree, during the take-off initial climb and his attention could have been diverted as part of troubleshooting the loss of engine power. The pilot’s diverted attention most likely allowed for the aircraft to exceed its critical angle of attack, resulting in a stall and ensuing spin at an altitude too low for recovery.
Accident 2
The pilot and student pilot-rated passenger were in a high-performance aeroplane and inbound for landing. Multiple witnesses saw the aeroplane on the downwind leg of the airport circuit, one witness estimated that the aeroplane was lower and closer to the runway than usual. Witnesses then saw the aeroplane begin a left turn, and one reported that the aeroplane then rapidly transitioned to a nose-down descent. The wreckage location corresponded to an extended downwind-to-base turn, there was ample space available for the pilot to initiate the turn to final without excessive flight control inputs. The aeroplane appeared to be in the landing configuration, and debris distribution and damage indicated a near vertical, nose-down impact, consistent with the aeroplane impacting the ground while in a spin. Post-accident examination revealed evidence that the aeroplane’s enginedriven vacuum pump had recently
“It is likely that the pilot became distracted and the aircraft got too slow” 40 | FLYER | April 2021
failed. Such a failure would have resulted in multiple visual alerts, caused the vacuum-operated instruments to become inoperative, and prevented operation of the aeroplane’s speed brakes. Although none of the systems that relied on the vacuum pump were critical for visual flight rules operation, such a failure would have presented an operational distraction to the pilot, which would have competed for his attention while flying in the pattern. Based on witness reports and the location of the wreckage, it is possible that he extended the downwind leg to attempt to manage the failure, or in an effort to slow the aeroplane further in order to land without the speed brakes. The presence of a systems failure may have exceeded the pilot’s capability to appropriately divide his attention between aeroplane control and systems management. It is likely that the pilot became distracted during the landing approach and allowed the aeroplane to slow down and exceed its critical angle of attack during the turn from the downwind to base leg, resulting in an aerodynamic stall and spin at an altitude too low for recovery.
Accident 3
The pilot was taking off for a personal flight. According to onboard data, when the aeroplane reached about 150ft agl, the pitch began to increase. Over the next four seconds the aeroplane’s altitude began to increase as the ground speed decreased. The aeroplane then banked to the left and descended nose-down to impact east of the runway. A witness observed that when the aeroplane reached about 100ft above the runway, the landing gear was retracted. He then diverted his attention and shortly after, he heard an impact. The aeroplane was recorded by airport security video just before ground contact in a near vertical descent (consistent with stall) with the landing gear extended. The pilot previously
Mark Mitchell
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erhaps it’s the natural cycle of the time it takes to produce an accident report following the event itself, or perhaps it’s the result of reduced flying activity in recent months, but finding an original topic for analysis has not come easily this month. There has been no shortage of reports but they mostly follow an all too familiar sequence, loss of control (LOC) leading to impact with terrain and a minimum of serious injury. This is, of course, familiar territory but why, if it’s so familiar, are so many of us still falling victim to this type of accident?
