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…
Steve Ayres
17 February 2021
Perhaps 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?
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.
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.
“It is likely that the pilot became distracted and the aircraft got too slow”
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 engine-driven vacuum pump had recently 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.
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 reported having physical difficulties manually retracting the landing gear, and as a result, he would use one hand to hold onto something in the cockpit to brace himself, and the other hand to operate the retracting handle assembly ‘Johnson bar’.
To assist in retracting the landing gear, the pilot would also slow the aeroplane, which was supported by the data recorded by the Stratus 2S for the accident flight and a previous uneventful flight that was examined. It is likely that the pilot intentionally increased the aeroplane’s nose-up pitch and decreased the aeroplane’s speed to assist him to retract the landing gear. The ultimate result was the aeroplane exceeding its critical angle of attack and it entered an inadvertent stall.
The owner of the aeroplane, who was a flight instructor, completed a 100-hour inspection on the light sport aircraft before another flight instructor departed in the aeroplane on an instructional flight. That instructor reported that, during take-off, the engine was not producing full power and experienced a momentary loss of power. He returned to the airport and landed uneventfully.
“The aeroplane appeared to enter a stall during a left turn back toward the airport”
The owner examined the aeroplane and concluded that the loss of power was likely due to vapour lock. They left the engine cowl open to cool the engine, and about two hours later, the owner/flight instructor departed with a student on the accident flight. The student stated that, after take-off, the engine sputtered and the flight instructor took control. He had no recollection of the accident other than that the altimeter indicated 240ft.
Recorded data revealed that the aeroplane experienced a significant reduction in engine rpm for unknown reasons about 35 seconds after take-off. The throttle was reduced, and the aeroplane reached a maximum altitude of about 250ft at an airspeed of 44kt.
Vertical acceleration began to oscillate, the aeroplane was banking to the left and reached a 68° left wing down bank angle. It then began to descend rapidly, the throttle was advanced and engine speed increased.
However, shortly thereafter, the aircraft impacted the ground.
Examination of the airframe and engine did not reveal any pre-impact anomalies. The aeroplane’s flight track and recorded data were consistent with it entering a stall during a left turn back toward the airport.
The pilot reported that, after a cross-country flight, he wanted to fuel the aeroplane at the airport, but the fuel tanks were locked. He then flew to a nearby airport to fuel the aeroplane, but once over the airport, he was told via the UNICOM frequency that the airport was closed for construction and that he would not be able to land.
He returned to the departure airport, and as he reduced power and performed his pre-landing checks, the engine lost total power. He switched from the left fuel tank to the right fuel tank, turned the fuel pump on, and pumped the throttle to no avail. He continued downwind and abeam the runway numbers and added flaps.
On base, he felt the aeroplane was low and decided to head straight for the runway. Near the beginning of the runway, the aeroplane aerodynamically stalled and landed hard. The aeroplane slid about 300ft and came to rest in the grass adjacent to the runway. The aeroplane sustained substantial damage to the left wing.
The FAA inspector reported that he verified that the left fuel tank was completely empty. He also removed the drain plug from the carburettor, which was also empty.
Additionally, the insurance adjuster reported that he looked into the fuel tanks with a scope and saw that the left fuel tank was ‘bone dry’, and that the right tank had about 12 gallons of fuel.
We all have deeply entrenched memories from the early days of our flying training. Some have been indelibly etched through near-death experiences, ‘Whatever happens, I’m not going to do that again’, and others, as pearls of wisdom from our various instructors.
Many of my instructors were ex-military (thank you, Channel Islands Aero Club) or serving in the military, but they all sang from the same song sheet when it came to dealing with the unexpected. The narrative began with, ‘Fly the f***ing aeroplane’. It didn’t matter what that unexpected event was or how grave the emergency, nothing had a greater importance than flying the aircraft safely. Either while getting on with emergency drills or simply remaining in control up to the point of touch down!
Much of that instruction about ‘flying the aeroplane’ during emergency handling revolved around setting a power (if you had any!) and maintaining an appropriate ‘attitude’ for the flight parameters at any given time. Mostly, this was the cruise attitude or with little to no power, a glide attitude. As a result these pictures of where to put the nose of the aircraft relative to the horizon, either visually or on instruments, were burned onto the retina, endlessly taught and constantly practiced.
As much as we may have the urge to try other attitudes voluntarily or involuntarily, perhaps fuelled by the panic of a particular situation, they will never defy the laws of physics. And the consequences of loss of control will inevitably be far, far worse than if we remain in control and guide our stricken airframe to a forced landing.
So, how to avoid becoming another one of these dire statistics? Given our limited opportunities for flying at the moment the temptation will be, of course, to pick a nice sunny day and simply enjoy the pleasures of being airborne.
But do think about stealing a couple of minutes to remind yourself of that glide attitude following a simulated and sudden loss of power. So that – should the ‘unthought-of’ happen – your instincts are the correct ones and you Select the correct attitude, Hold It and Trim… instinctively!
