Occurrences & Incidents May - August 2021
Under investigation. The pilot was on his first flight on type and flew beyond gliding range of the gliding airfield. A late decision was made to outland, but the selected paddock was uncultivated and covered in large tufts of grass and scattered surface rocks. The pilot landed along a ridgeline and had to conduct a ground loop to prevent collision with a post and wire fence. The fuselage suffered stress cracks aft of the cockpit and the starboard wing suffered damage where it struck rocks.
Shortly after becoming airborne during an aerotow launch the pilot heard a significant air leak and noticed that the canopy was not fully locked. A quick check revealed that while the rear locking pin was partially engaged, the forward pin was not. After releasing from tow, the pilot slowed the glider and was then able to fully engage both locking pins. The pilot decided to break off the flight and conducted a safe landing. Subsequent inspection found no defect with the operating mechanism. The glider’s canopy locking system employs two sliding pins, each driven by a rod connected to the actuating handle. The first three quarters of the handle movement locks the rear pin, and the remaining ¼ slides the rod to the front pin. The pilot suspects his pre-take-off checklist was interrupted when he became distracted by the wingtip runner connecting the tow rope to the glider’s release. The pilot stated that they should have diligently completed the checklist before having the rope attached.
As the pilot entered a thermal at about 3600ft, they sighted a juvenile wedge-tailed eagle about 1000ft below. During the climb and at about 4,600ft the glider was struck by the eagle. The pilot, who was scanning for another glider about to enter the thermal, did not see the eagle hit the glider but heard the thud and noticed feathers flying on the port side of the fuselage. The pilot conducted a control check and ascertained the glider was flying normally with no abnormality. The pilot continued to climb to gain enough heigh to glide back to the home airfield to check for damage. After a safe landing the pilot inspected the airframe and found the eagle had hit the port wing causing a localised minor indentation and some scratches in the paint on the upper surface of the wing. The glider was subsequently repaired and returned to service.
While conducting the annual post-maintenance flight the pilot pulled the undercarriage up, but it jammed halfway and could not be raised further nor lowered. The pilot landed with the undercarriage partially down, and the mainwheel retracted upon landing.
Subsequent inspection identified the castellated nut on the wheel axle had been overtightened, which had a clamping effect on the articulated joint at the axle sufficient to prevent the undercarriage from being locked up or down. The tension was adjusted by backing-off the nut by one Castellation and the undercarriage was able to be operated normally.
During and aerotow and at approximately 4000' (2920' AGL), the glider pilot climbed out of station and started to lift the tail of the tow plane. The tow pilot was about to activate the tow release when the glider pilot released from tow. Both aircraft landed safely, and a debriefing was held with the Duty Instructor.
The flight was the pilot’s third solo after 17 dual training flights, having recently returned to gliding after a break of several years. The glider pilot reported that the tow plane climbed unexpectedly, then descended, at which point the glider unexpectedly climbed, resulting in the glider being significantly out of station above the tow plane. The glider pilot also reported that he had misidentified the tow release handle, and when he attempted to release from tow, he may have inadvertently pulled the wheel brake control, which is a similar shape to the release handle but a different colour. After realising that the tow cable had not released, the glider pilot then identified and operated the cable release control. The tow pilot, who is the club’s Tugmaster and an experienced sailplane pilot, advised he was about to release the glider when the tow rope was released by the glider pilot. The tow pilot reported that the air was particularly smooth, and that the combination had climbed well above the temperature inversion when the incident occurred. The tow pilot stated there was no environmental turbulence at any time during the launch. Investigation by the CFI concluded that the glider pilot probably operated what he thought was the release handle and most likely performed a climbing clearance turn to the right. By the time he realised that the cable had not released, he then identified and operated the actual release control, by which time the glider was most likely well above the tow plane and pulling the tail of the tow plane upwards and to the right. The CFI has asked his instructors to reinforce with their pilots the correct release procedure, including to “locate, identify and operate” the release handle and to verify that the rope has gone before commencing a clearing turn.
Tug upsets are serious and have caused the deaths of a several tug pilots around the world. If the glider is allowed to climb rapidly behind the tug, it can very quickly become impossible to prevent it accelerating upwards in a slingshot action (rather like a winch launch) and tipping the tug over into a vertical dive. Once that has happened, the tow pilot will only be able to recover provided there is sufficient height. Downward displacement of the glider below the slipstream is quite acceptable, but upward displacements are much more critical. The glider pilot must release immediately if the glider is going high and the tendency cannot be controlled, or the pilot loses sight of the tug. The circumstances which make tug upsets more likely are:
• a light pilot flying close to the minimum cockpit weight;
• an inexperienced pilot - particularly wire launch pilots with little recent aerotow experience;
• glider with a belly or CG hook;
• an all-flying tailplane, or a glider with very light elevator forces;
• short rope; or
• turbulent conditions.
A vertical upset can also arise when the glider releases if the glider turns before the pilot has confirmed that the rope has separated. A tug upset is less likely to occur if the glider pilot avoids transitioning above or below the slipstream prior to release. If towing in low-tow, then the glider pilot should release from low-tow and vice versa. It is essential to check that, prior to release, the airspace is clear (a) to the right where the glider is just about to turn, and (b) to the left and below where the tug is just about to descend. The glider pilot must then ‘Locate, Identify, Operate’ the tow release. The release should not be operated until it has been positively located and identified as the one required. This eliminates any possibility of error in selection of the wrong control. This principle applies to all ancillary controls. When ready, the glider pilot will pull the release, and must observe the rope fall away before beginning their clearance turn to the right while simultaneously applying normal targeted scan. The release should be operated while the towrope is still under some tension, and the tug pilot, after feeling “release” should check that the glider has in fact released and begin a descending turn to the left. Post release actions should then be carried out and transition from launching pilot to soaring or landing pilot. For further information on tug upsets, please refer to Section 10.3 of the GFA Aerotowing Manual.
The glider took off with the airbrakes unlocked, and during the aerotow they deployed. The tow pilot signalled the glider pilot by waggling the rudder, and the glider pilot immediately closed the airbrakes. The flight continued uneventfully.
The pilot advised that their take-off procedure in this flapped type glider was to start the initial aerotow ground roll in negative flap to achieve aileron control at low speed, and to then move the flaps to neutral once aileron control has been obtained and the airspeed has increased. In addition, and to prevent the glider over-running the tow rope, the pilot applies the wheel brake that is actuated by the application of full airbrakes. Once the slack in the rope has been taken up and the tow pilot has opened the throttle for launch, the glider pilot will then close and lock the airbrakes. On this occasion, the pilot closed but did not lock the airbrakes and they deployed early in the climb. The pilot stated “During the first phase of the launch, I changed to neutral flap (as per my normal procedure) and was trying to work out why the glider felt different when I saw the tug rudder waggle and immediately closed the airbrakes. Prior to this incident, I have had 555 flights in this glider, with 1560 hours without incident. I was too complacent on this occasion.” After the flight, the glider pilot discussed this incident with his CFI and expressed their embarrassment for the oversight. The tow pilot advised that they did not notice any difference with the glider on tow, having previously towed a heavy tow-seater. However, the tow pilot stated that, in line with their training, they looked in the mirror shorty after the combination became airborne and observed the red airbrakes were showing above the wings and immediately gave the rudder waggle signal.
This very experienced pilot attributed this procedural lapse to complacency, which is one of the biggest enemies a pilot can face. Over time, flight related tasks can become rote actions performed without the necessary forethought to ensure we’re not acting out of habit. All pilots can be vulnerable to making errors if they become complacent by allowing habits and expectations to influence their actions. Taking actual steps to direct attention and methodically verify the status of an action can reduce your chances of making errors.
Grob G103A Twin II Acro
During a winch launch and at about 500ft AGL, the pilot gave a too fast signal and the front canopy departed the aircraft. The command pilot released the cable and conducted a safe circuit and landing. The canopy was substantially damaged. The experienced command pilot advised “I closed the window and checked the canopy was locked before take-off. I recall moving my left arm back from the trim - not sure why now – and can only think loose clothing may have moved the canopy handle but I don’t remember any resistance”. The pilot’s CFI noted that the glider has a lever actioned canopy release, and it is possible the pilot may have caught his sleeve on the canopy release lever causing it to either become fully or partially unlocked. However, conditions on the day were gusty and this, coupled with the pilot giving the too fast signal and the canopy seals being worn, may have generated sufficient force to dislodge the canopy locking mechanism that resulted in the canopy departing the airframe.
Club Libelle 205 - Tecnam P2002
A glider was being pushed onto the runway threshold for a launch when the crew sighted an aircraft established on final approach. The glider was immediately pushed back clear of the runway and the aircraft completed a normal landing and vacated the runway.
The ground crew had been monitoring the radio for several minutes and was aware of other traffic in the vicinity. After visually clearing the airspace, the ground crew gave a broadcast on the CTAF advising they were entering the runway for a glider launch. In the absence of any further radio calls, the ground crew pushed the glider onto the runway while the tow plane held at the taxiway. While moving the glider onto the runway, the ground crew continued to monitor the airspace and observed a powered aircraft on final approach about one mile away. The glider was immediately pushed clear of the runway and the tow pilot was advised not to enter the runway. The powered aircraft landed and exited the runway, and no radio calls were heard. A member from the gliding club went to talk to the pilot of the powered aircraft but did not catch up with them. The aircraft was from the local aero club and a check of the radio identified it had been incorrectly set and was not on the aerodrome CTAF. The ground crew reported that the aircraft did not display landing lights on approach, which made it more difficult to sight.
The concept of ‘see-and-avoid’ in conjunction with an active listening watch is the best defence against the risk of collision. However, alerted see-and-avoid is not always effective as it relies on pilots being on the correct frequency and understanding the transmitted information. In this case, the pilot of the powered aircraft did not recognise they had set the wrong frequency on the radio, and while the ground crew followed best practice, they still failed to observe the powered aircraft on approach – most likely because it was on a long shallow approach and its landing lights were not illuminated. CASA guidance in CAAP 166-1, under the heading ‘Related safety actions at non-controlled aerodromes’ at paragraph 2.2 states: “Pilots are encouraged to turn on external aircraft lights, where fitted, when in the vicinity of a non-controlled aerodrome. These lights should be kept on until the aircraft has landed and is clear of all runways.”
The pilot joined circuit slightly lower than normal and, despite losing further height due to sinking air, did not modify their aiming point and turned onto final approach at a very low height.
Returning to the airfield following a 150km cross-country flight, the pilot flew across the upwind extended centreline of the operational runway at about 1500ft AGL, and at a distance of about 2NMS, towards the dead side of the circuit. The pilot then turned onto the crosswind leg for RWY30, about 500 metres upwind at about 1400ft AGL. The glider flew through areas of strong sink and the pilot eventually turned onto the downwind leg at about 700ft AGL. The glider continued to fly through sinking air losing height, but the pilot maintained a standard circuit pattern. The base leg turn was made at a height of about 300ft AGL and the glider attained a wings level attitude at about 100ft AGL. The pilot’s CFI witnessed the landing and spoke with the pilot, who advised they wanted to land close to their car and tow gear. The CFI counselled the pilot and reiterated the advice in Operations Safety Bulletin (OSB) 01/14 ‘Circuit and Landing Advice’. To quote from this document, “The final turn must be conducted at a safe height, preferably not lower than 300ft AGL, and at the calculated approach speed, having regard to the local conditions. Good energy management is critical to safety, and to setting up a good stable approach from which a safe landing can be conducted. There is strong evidence to suggest that poor landings, or landings causing damage or injury, are much more likely to result if the final turn is executed too late, too close to the ground or with poor energy management, all of which make a stabilised approach and controlled landing much more difficult.”
It has been noted over many years that a significant percentage of reported accidents and incidents have resulted from pilots modifying their normal operating procedures, or abandoning accepted best practice, for no reason other than convenience. Good operating procedures and flying standards are developed over time and built on the experience of many pilots and many mistakes. There is no doubt that convenience can be a seductive force, but pilots must resist the temptation and recognise that even slight departures from standard accepted good practice can have severe consequences.
While on the base leg of the circuit the tug pilot heard two radio transmissions that were carrier wave only (no voice). Shortly after turning onto final approach, the tug pilot heard a radio transmission advising “I am immediately underneath you”. The tug pilot then noticed a glider on his left-hand side, and slightly behind and below. The tug pilot immediately selected full throttle, turned away from the glider and conducted a go-around procedure.
Returning to the airfield following a local flight, the glider pilot made a broadcast on the CTAF that he was joining final 3NMs from the runway. At that time the tug was joining downwind, and its pilot heard the call. However, due to other radio traffic from airfields in the area broadcast area, the tug pilot did not hear the identity of the aerodrome called by the glider pilot and so did not associate it with his circuit. The tug pilot made a further radio call upon turning onto the base leg that was heard by the glider pilot, but the glider pilot did not hear what leg of the circuit was called and, because he could not see the tug, thought the tug was joining downwind. The glider then made a call on the CTAF to advise he was on final approach and number 1, but he did not receive an acknowledgement. Very shortly afterwards the glider pilot saw the tug on his left turning onto the base leg towards the glider and a little higher. The glider pilot reported being surprised by the tug’s position, as he had assumed it would be mid-downwind at that time. The glider pilot then lost sight of the tug as it went behind the glider, and called “Tug, I am just below you” three times – each call being a few seconds apart – but he did not hear a response. Shortly afterwards, he observed the tug turning away to the right about a wingspan to the right, and slightly above, the glider. The Tug pilot reported that he heard two carrier wave transmissions when on Base leg and then a voice call when the glider was very close to him on final approach, at which stage he took evasive action and conducted a go-around. A subsequent check of the radios in both aircraft’s proved they were serviceable, but while the FLARM in the glider was also serviceable and had the current firmware update, the unit in the tug had an unserviceable aerial. It was also identified that the tug FLARM did not have any audio warning. The tug FLARM was fixed, and a modification was made to provide an audio signal to the pilot’s headset.
• Several aerodromes in the area share the same frequency, and there was a lot of radio chatter heard from traffic at the other sites.
• As it was not a day conducive to cross-country flight, a glider joining final at 3NMs (5kms) was unusual.
• While the tug pilot heard an aircraft call final at 3NMs, he could not see an aircraft in that position and assumed it was an aircraft flying into another site.
• The glider pilot was unsure of the tug’s position when he heard the first call and did not consider calling the tow pilot to confirm.
• Although both aircraft had working radios, the tug pilot did not receive a clear voice transmission from the glider pilot until the tug was near the glider.
• Both aircraft were fitted with FLARMs, but neither pilot received a collision alert as the unit in the tug was faulty.
Subregulation 166C (1) of CAR requires that a broadcast be made to avoid the risk of collision if the aircraft is carrying a serviceable VHF radio and the pilot-in-command holds a radiotelephone qualification. When operating at busy uncontrolled airport, pilots are required to utilise alerted see-and-avoid procedures wherever possible in order to decrease the risk of collisions with other aircraft. Pilots, therefore, need to conduct an effective radio serviceability test and be able to recognise a possible radio failure. Pilots must be alert to the fact that they cannot assume that radio communication equipment is serviceable until two-way communications have been established. Pilots should take extra care to avoid any conflict by repeating broadcasts, or asking for confirmation from the other aircraft when unsure of its intentions or a message has not been understood. For further information, refer to CAAP 166-1 ‘Operations In the Vicinity of Non-Controlled Aerodromes’.