Occurrences & Incidents March - April 2021
6-Mar-2021 SAGA
Astir CS 77
Terrain Collisions
What Happened
During final approach, the pilot realised he had not lowered the undercarriage. The pilot changed hands on the control column, and inadvertently pushed forward on the stick coincident with lowering the wheel. The aircraft flew onto the ground heavily at approach speed. The pilot suffered back injury and the glider was substantially damaged.
Analysis
The glider was launched by winch and upon release the pilot turned downwind to chase a thermal. After a minute or so the glider had lost altitude and the pilot broke off the flight and flew towards the circuit joining area. The pilot stated that he joined circuit lower than usual and only realised prior to touchdown that the undercarriage had not been lowered. He said that he swapped hands to move the undercarriage lever, located on the right side of the cockpit, into the lowered position. At that moment the glider pitched forward and struck the ground hard. A witness on the ground stated the glider “flared a little higher than normal and suddenly pitched forward and touched down with a puff of dust onto the rubble runway”. The witness claimed the glider had plenty of speed when it hit the ground, and that it skidded for 70 metres before coming to a stop. The witness initially thought the glider had landed with the undercarriage retracted, however it soon became apparent that the undercarriage was down and had collapsed on impact. The pilot exited the glider before ground crew arrived and complained of a very sore back. He was immobilized and transported to hospital by ambulance. Subsequent inspection of the glider revealed the impact had broken several bulkheads as well as the undercarriage system. Potential causal factors include breaking off the flight too late, increased workload and fixation on the landing area due to the low circuit, failure to configure the aircraft for landing before joining circuit and forgetting to complete the pre-landing checklist.
Safety Advice
Circuit and landing are high workload environments and pilots are encouraged to reduce their workload by configuring the aircraft for landing at an early stage. GFA training is to lower the undercarriage once the decision to land has been made and the undercarriage should be down before the circuit is joined. When the aircraft is configured early, the risk off a mishap from the omission of the pre-landing checklist, for whatever reason, will be reduced. Refer also to OSB 01/14 'Circuit and Landing Advice'. This accident also highlights the risk of injury to the pilot who attempts to lower the undercarriage in the late stages of the approach. Where the undercarriage control lever is situated on the starboards side of the cockpit, a pilot has to change hands on the control stick to lower the undercarriage. If the glider is not trimmed, it can tend to drop the nose during this action. Over the years there have been many accidents, including fatal, caused by the pilot changing hands to lower the undercarriage at low height. On the other hand, most gliders only suffer minor scratches from a well-conducted ‘wheel-up’ landing.
6-Mar-2021 SAGA
Astir CS 77
Terrain Collisions
What Happened
During final approach, the pilot realised he had not lowered the undercarriage. The pilot changed hands on the control column, and inadvertently pushed forward on the stick coincident with lowering the wheel. The aircraft flew onto the ground heavily at approach speed. The pilot suffered back injury and the glider was substantially damaged.
Analysis
The glider was launched by winch and upon release the pilot turned downwind to chase a thermal. After a minute or so the glider had lost altitude and the pilot broke off the flight and flew towards the circuit joining area. The pilot stated that he joined circuit lower than usual and only realised prior to touchdown that the undercarriage had not been lowered. He said that he swapped hands to move the undercarriage lever, located on the right side of the cockpit, into the lowered position. At that moment the glider pitched forward and struck the ground hard. A witness on the ground stated the glider “flared a little higher than normal and suddenly pitched forward and touched down with a puff of dust onto the rubble runway”. The witness claimed the glider had plenty of speed when it hit the ground, and that it skidded for 70 metres before coming to a stop. The witness initially thought the glider had landed with the undercarriage retracted, however it soon became apparent that the undercarriage was down and had collapsed on impact. The pilot exited the glider before ground crew arrived and complained of a very sore back. He was immobilized and transported to hospital by ambulance. Subsequent inspection of the glider revealed the impact had broken several bulkheads as well as the undercarriage system. Potential causal factors include breaking off the flight too late, increased workload and fixation on the landing area due to the low circuit, failure to configure the aircraft for landing before joining circuit and forgetting to complete the pre-landing checklist.
Safety Advice
Circuit and landing are high workload environments and pilots are encouraged to reduce their workload by configuring the aircraft for landing at an early stage. GFA training is to lower the undercarriage once the decision to land has been made and the undercarriage should be down before the circuit is joined. When the aircraft is configured early, the risk off a mishap from the omission of the pre-landing checklist, for whatever reason, will be reduced. Refer also to OSB 01/14 'Circuit and Landing Advice'. This accident also highlights the risk of injury to the pilot who attempts to lower the undercarriage in the late stages of the approach. Where the undercarriage control lever is situated on the starboards side of the cockpit, a pilot has to change hands on the control stick to lower the undercarriage. If the glider is not trimmed, it can tend to drop the nose during this action. Over the years there have been many accidents, including fatal, caused by the pilot changing hands to lower the undercarriage at low height. On the other hand, most gliders only suffer minor scratches from a well-conducted ‘wheel-up’ landing.
7-Mar-2021 NSWGA
SZD 55-1
Landing gear/Indication
What Happened
During an aerotow launch the tug accelerated for take-off prior to the slack being taken-up in the tow rope. The glider was thrust forward, and the mainwheel struck a large tussock of grass that bounced the glider prematurely into the air. When the glider touched down again the undercarriage partially retracted but the glider and tug became airborne and climbed away. The glider pilot, after lowering the glider’s undercarriage, maintained a routine and normal aero tow, separation, thermal flight, and subsequent uneventful landing.
Analysis
The undercarriage mechanism was subsequently examined, and it was identified that the port-side lower overlocking arm had been installed 180 degrees around. This prevented that side of the glider’s undercarriage leg from locking over centre. When the glider travelled across the rough ground, the undercarriage mechanism moved resulting in the starboard leg unlocking. The port-side lower overlocking arm was reinstalled correctly, returning the mechanism back to specification.
Safety advice
Aviation safety relies heavily on maintenance. When it is not done correctly, it contributes to a significant proportion of aviation accidents and incidents. Some examples of maintenance errors are parts installed incorrectly, missing parts, and necessary checks not being performed. In comparison to many other threats to aviation safety, the mistakes of an airworthiness inspector can be more difficult to detect. Often times, these mistakes are present but not visible and have the potential to remain latent, affecting the safe operation of aircraft for longer periods of time. Inspectors are confronted with a set of human factors unique within aviation. Often times, they are working alone, in confined spaces, and in a variety of adverse temperature/humidity conditions. The work can be physically strenuous, yet it also requires attention to detail. Being aware of the human factors involved in maintenance can lead to improved quality. For further information, refer to section 3.2 of Basic Sailplane Engineering dealing with ‘Systemic and Human Factors’.
9-Mar-2021 VSA
LS 3-a
Outlanding
What Happened
During an aerotow from an outlanding paddock, the pilot lost directional control when the wing dropped into the stubble and he released from tow.
Analysis
The pilot was competing in the Victorian State Championships and was on the last leg of an assigned area task. On nearing the ‘control’ turnpoint, and at a distance of about 15kms from the home airfield, an outlanding became inevitable. The pilot conducted a safe landing in a harvested paddock containing 30cm wheat stubble. After assessing the suitability of the paddock, the pilot contacted the competition organisers and arranged an aerotow retrieve. Due to an absence of ground crew, the pilot conducted a ‘wing down’ take-off behind the tow plane. After taking-up the slack in the rope, the tow plane accelerated for take-off creating a cloud of dust that reduced the glider pilot’s visibility. The drag of the wing on the ground caused the glider to veer 20 degrees to the right before the pilot got the wings level. While attempting to straighten the glider, the left wing contacted the ground and began to drag in the stubble. The pilot decided to release from tow and pushed the control column forward to keep the tail in the air as the glider conducted a ground loop. The glider was undamaged and subsequently retrieved by trailer.
Safety Advice
During an outlanding retrieve it is sometimes not possible to find a person to hold the wingtip for the launch. This necessitates a wing-down take-off, which is quite feasible but only if the surface is suitable. Any vegetation over about 10cm long should rule out a wing-down take-off, as the glider pilot will not be able to keep straight due to the drag of the wing in the grass. Even with a wing-tip holder, the pilot may still be in trouble. Modern gliders often drop wings some considerable time after the wingtip holder has let go, a function of their rather high angle of attack with the tail on the ground, combined with the spiral prop wash from the tow plane. If the wing drops into long stubble or grass, a ground loop is a certainty. Don’t take chances with long stubble or grass and don’t drop your guard just because it looks like it’s only in small patches. If in doubt, get the trailer.
20-Mar-2021 GQ
ASK 21
Low Circuit
What Happened
During circuit to land the glider passed through a heavy rain shower. The pilot flew too far downwind for the conditions and conducted a very low approach to landing..
Analysis
The pilot was conducting an Air Experience Flight in overcast conditions with occasional showers increasing in frequency. After been airborne for about 30 minutes the pilot decided the break off the flight and head back to the circuit for landing. The pilot observed local rain showers approaching the airfield from the South and extended the flight by a few minutes to allow the nearer shower to pass. The pilot joined circuit for RWY 04 with the windsock indicating a weak crosswind. Shortly after joining circuit for RWY 04 the Duty Instructor on the ground made a radio call to the pilot suggesting he consider landing on RWY 22, which was more into wind. The pilot decided to continue to land on RWY 04, but the glider flew into another rain shower and the pilot noticed the glider was drifting away from the runway. The pilot stated: “This confirmed my sense of drift, and so I adjusted to around a 45-degree angle toward the strip. By this time, we started to enter the influence of the shower and light rain started to fall. Another more urgent call came over the radio to modify my circuit. We were now roughly in line with the touch down point, so I curtailed the downwind leg and pointed us straight toward the airstrip.” On turning base the rain got heavier and the glider’s descent rate increased; possibly due to sink and rain contamination on the wings. The pilot flew a very low approach around the Club hangar, touched down on the runway threshold and came to rest about 300 meters down the runway. The CFI noted that the pilot committed himself to a landing on RWY 04 and did not realise how heavy the rain was or the effects it might have on the aerodynamics of the glider.
Safety Advice
Many modern glider aerofoils are severely affected by rain, resulting in reduced performance and an increase in stall speed. This is because drops of rain on the wing disturb the airflow, thus reducing lift and changing the stall characteristics. Most manufacturers suggest adding at least 5 Knots to the approach speed to take into account the increased stall speed. Flying too fast with contaminated wings will severely reduce the glide performance and will lead to increased sink rates.
2-Apr-2021 VSA
Zephyrus
Hard landing
What Happened
An aerotow launch in slight tailwind conditions was aborted by the glider crew when it became apparent that the combination was not climbing satisfactorily.
Analysis
Weather conditions during the day were benign, with light and variable wind progressively moving to the East. Operations were being conducted on RWY 27 in accordance with local procedures for the conditions. The flight was a training sortie involving a solo student who was flying under supervision without reference to the ASI and Altimeter to qualify for the ‘A’ Certificate. Just prior to the flight the wind had moved to the East and had increased to a few knots. The gliding operation continued with a slight tailwind, as the two Pawnee tow planes were providing safe launches. However, the tow plane for the incident flight was low-powered and unable provide the same performance as the two Pawnees. The initial ground roll was well managed by the student flying but was longer than usual due to the tailwind component. The glider became airborne first and maintained a height of about 2 metres above the runway as the tow plane got airborne and began a shallow climb. Due to the long ground run and slow climb rate, it became obvious to the flight instructor that the combination would pass very low over the airfield boundary. To avoid getting into the non-manoeuvring area and while only about 5 metres above the runway, the instructor activated the tow release with the aim of landing straight ahead. The student was also concerned about the slow climb rate and had been focussing on the boundary fence that was looming ahead. When the glider was released from tow, the student pilot reacted by opening the airbrakes and simultaneously pitched forward on the control column. Due to the low height, the glider almost immediately struck the ground nose first, impacting on the front skid near the fuselage mounting point. Although the instructor was maintaining a defensive posture on the controls, the action happened too fast for the instructor to react. The glider rolled 50 meters and came to rest about 200 meters from the airfield boundary. The tow pilot continued to climb and then joined circuit and landed safely. Initial inspection of the glider identified the nose skid had cracked at a previous repair. A detailed inspection later identified the forward skid mounting tube had slightly deformed. The glider was repaired and returned to service. The instructor debriefed the student who explained that he was concerned that they were running out of runway and when the release was activated, he felt he needed to get the glider on the ground immediately to avoid running into the airfield boundary fence. The student acknowledged that his actions were inappropriate and that he should have maintained the landing attitude. The instructor advised they did not assume control before releasing from tow because they believed the student could handle the emergency and that he had allowed sufficient room for the glider to land straight ahead. The instructor had conducted most of the student’s flight training and advised the student had not reacted in that way previously. The instructor considers it is likely the student was startled by the sudden release from tow at a critical stage of the launch and, in the absence of the ASI to confirm the aircraft’s speed, he acted instinctively to lower the nose and get the aircraft on the ground. The instructor stated that the aircraft struck the ground almost coincident with the over pitching of the elevator control and that he had no time to react.
Safety Advice
1.Startle Response
The startle response is the physical and mental response to a sudden unexpected stimulus. More commonly known as ‘fight or flight’, this physiological reaction occurs in response to what you may perceive as a harmful event, attack, threat to your survival or simply fear. The fight or flight response evolved to enable us to react with appropriate actions: to run away, to fight, or sometimes freeze to be a less visible target. In aviation, startle often occurs when in a highly dynamic, time-critical condition. Two systems in the brain—the reflexive fast system and the slow system—play different roles in our reaction to danger. The reflexive fast system acts immediately—in one twelfth of a second—by sending information directly to the sense organs through the thalamus to the amygdala. The slow system sends sensory information to the hippocampus and cortex for further evaluation. It’s slower because it requires conscious processing. Pilots finding themselves in non-routine, emergency and abnormal situations will have difficulties in recognising that a problem has occurred and difficulties in getting out of the normal mode of operations. While GFA does not have a formal policy with regards to ‘startle factor training’ as a specific issue, training in non-technical skills is required to recognise and manage situations that can occur in a sudden event. The idea is to give pilots the skills to manage a ‘startle’ type event. This training is also encompassed in the GFA’s Flight Review regime, where a pilot’s competency in emergency procedures is demonstrated in flight following simulation of the emergency by the instructor or examiner.
2.Control inputs close to the ground
Pilots should never use coarse elevator control inputs close to the ground, as gliders are sensitive in pitch and such action is inconsistent with a safe transition from a stabilised approach into the flare and landing. Course movement of the elevator control at low levels usually results in a sudden and unrecoverable steep dive into the ground. Instructors should also note that a student pilot’s sudden forward elevator control inputs, initiated at low level (under 100ft), will usually be beyond the limits of instructor intervention and safe recovery.
4-Apr-20211 WAGA
PW-6U
Hard landing
What Happened
The pilot was on their second solo flight and turned onto final approach somewhat higher than normal. The pilot deployed full airbrakes with the aim of landing abeam the control vans but rounded out too late and did not close the airbrakes. The glider struck the ground heavily on the main wheel and bounced back into the air. The pilot pushed the stick too far forward to recover resulting in the glider striking the ground hard a second time on the nose wheel. The front canopy ejected and the nose wheel inner tube burst.
Analysis
The pilot had struggled with the landing phase during training but had demonstrated consistency in recent weeks. On the day prior to the accident the pilot had flown on eight occasions in crosswind conditions and had demonstrated an ability to safely handle rope breaks in difficult situations. On the day of the accident the pilot also demonstrated rope breaks and unusual landings and was sent solo for the first time, and the flight was completed competently. On the second solo flight the pilot joined a high final approach that required the use of full airbrake to achieve the selected aiming point. The pilot was late to round out and forgot to ease closed the airbrakes to arrest the rate of descent. The glider struck the ground heavily and bounced back into the air. The pilot over corrected the recovery from the bounce and pitched too far forward on the elevator control causing the aircraft to strike the ground heavily on the nosewheel. The impact caused the canopy to eject and the nosewheel tube to burst, and the aircraft came to rest about 100 metres from the point of impact. A ‘hard landing’ inspection was conducted, and no further damage was identified. It was found the front canopy attachment was poorly adjusted and probably would not have ejected if correctly adjusted.
Safety Advice
When landing with full airbrakes the pilots should commence the roundout at a height sufficient to overcome the effect of inertia before the ground intervenes. If the pilot rounds out too late, the first action should be to reduce the airbrakes to arrest the descent rate. If the aircraft bounces, the pilot must ensure that any elevator control inputs are small. This is because the faster and cleaner the aircraft, the greater the pitch sensitivity. Recovery from a bounce should not be thought of in terms of 'control movements', but by reference to the glider's attitude and its position in relation to the ground. In other words, the pilot needs to recover by selecting an attitude which prevents any further climb. Bounces can be avoided by the pilot establishing the glider on the approach at the correct airspeed for the conditions using half or more airbrake. Pilots must endeavour to maintain the approach speed to roundout and aim to touch-down with low energy on the main-wheel and tailwheel simultaneously. For further guidance, refer to OSB 01/14 ‘Circuit and Landing advice’ and OSB 01/19 ‘Avoiding Approach & Landing Accidents During Training’.
9-Apr-2021 NGQ
Discus B
Consequential Events
What Happened
During a cross-country flight in weak conditions and at a height of about 2100ft AGL, the pilot decided to head back to the airfield some 31 kms away. The pilot recognised that the glider was below final glide height but pressed on in hope of making it. The pilot stated “with the area being surrounded by paddocks and suitable landing options I continued on the track back to the strip continuing to lose altitude. I lost track of my height and continued to speed up in a desperate attempt to make it back.” The pilot did not make the decision to conduct an outlanding until the glider was very low and made a turn at 100ft AGL to land in a paddock about 10kms from the airfield. The pilot stated: “I was still in disbelief that I had frozen up and did not land sooner. I believe that I put too much faith in the performance of myself and the glider to make it back.”
Analysis
Investigation by the Competition Director revealed that, at the time the pilot elected to return to the home airfield, he was in the vicinity of an agricultural airstrip where a safe outlanding could have been made. The pilot was also aware that he was below final glide and that conditions back to the home airfield were soft. At this point a sound option would have been for the pilot to search for lift while staying within safe glide of the agricultural airstrip, as the lift was going high enough to achieve a safe glide home. The Competition Director reviewed the flight with the pilot and identified some gaps in his knowledge and/or training. The pilot will undergo some remedial training to ensure he has the skills, aptitude, and attitudes to fly cross country safely.
Safety Advice
A common reason for outlanding accidents is the pilot not accepting soon enough that an outlanding is likely, and not prioritising the available height to allow them to fly to a good safe area. Pressing on with the flight in the hope that that all will be well is fraught with danger. Unlike landing at the home airfield where the runway layout, ground features and hazards are usually well known, when landing in a strange paddock the pilot is faced with the unknown. Such a situation demands the pilot take additional precautions to ensure a proper survey is undertaken of the landing area so as to identify all hazards and ensure a safe landing can be accomplished. To enable this check to be done adequately, pick a general area for outlanding at 2,000ft AGL; by 1,500 AGL a specific paddock should have been selected in that area and by 1,000ft AGL you should be committed to planning a circuit and landing into that paddock. Leaving an outlanding decision too late, at too low a height above ground, eats into the available time and eventually shuts off all the pilot’s escape routes. This often has fatal results. Under 700ft AGL, the number one priority is to land safely! For further advice, refer to: The ‘Outlanding’ section in Australian Gliding Knowledge; and
• A Guide to Outfield Landings – by Allan Latemore
