Aviation safety investigations & reports

LET National Corporation Blanik L13 , VH-GVS

Investigation number:
Status: Completed
Investigation completed


The pilot of VH-GKT was of Swiss nationality and he had arrived in Australia from Switzerland 4 days prior to the accident. He had been in Tocumwal for 3 days and he had attended an orientation and procedures briefing at the club on the morning of the first day. He was an experienced glider pilot and had flown two short check flights in a dual-control glider with a senior club instructor. No details of these flights were available, as the instructor who carried out the checks was the pilot in command of VH-GVS involved in the mid-air collision, and was fatally injured.

On the day before the accident, the foreign pilot flew a single-seat glider for a period of nearly 6 hours, after launching at approximately 1200 Eastern Summer Time ( EsuT). He stayed in accommodation at the airfield and attended a social function that evening but did not discuss his flights in detail with the gliding club staff who believed that he had flown in the local general area.

History of the flights

On the day of the accident, the pilot was launched in GKT by aerotow at about 1115. The aircraft was the same high performance single-seat glider that he had flown the previous day. He had not submitted a task declaration and club staff believed he was again intending to operate locally. Nothing was heard from the pilot of GKT throughout the day. The weather at the time was clear, no cloud below 10,000 ft and wind about 6-10 kts from the north with visibility greater than 15 km.

At about 1725 ESuT, GVS, a tandem two-seat glider, was launched by aerotow from runway 36. The front seat was occupied by an inexperienced pilot receiving refresher training from the club's senior instructor, located in the rear seat. The aircraft released from the tug at about 2,300 ft AGL and was seen to begin normal slow-speed manoeuvring in the upwind position, north-west of the field. It had been released for only about 2 or 3 minutes before the collision with GKT.

Sequence of events

GKT was observed to approach the circuit at high speed from the north-west by an eye witness located at the launch area near the end of the runway. At about 2 km from the airfield, the glider was observed to pull up rapidly and impact GVS.

The nose of GKT initially contacted the leading edge of the left wing of GVS from the left front quarter at an angle of about 55-60 degrees while banked about 15 degrees right. GVS was in slightly descending flight and probably banked slightly left. The nose of GKT then penetrated the centre section of GVS just behind the rear cockpit.

The collision destroyed the cockpit of GKT, severely damaged the left wing and wing attachment points at the centre section, allowing the broken left wing and complete right wing to detach from the aircraft. The T-tail was broken off at the end of the tail-boom and the fuselage continued through the centre section of the other glider. The fuselage section of GKT continued in the direction of flight until it impacted the ground several hundred metres from the collision point. The pilot received fatal injuries.

The outer half of the damaged left wing of GVS detached from the airframe. The relatively undamaged right wing (still loosely attached to the airframe) rotated around the destroyed centre section, until it was upside down on the left side of the fuselage, as the aircraft descended in a flat spin.

The initial impact of the left wing of GKT destroyed the canopy of GVS, and the damage to the centre section and seat harness attachment points caused the rear seat occupant to fall from the aircraft. Both occupants of GVS received fatal injuries, either at the point of collision or the subsequent ground impact.


Flight history of GKT

No evidence was found to indicate where the pilot of GKT had been flying during the approximately 6 hours since the glider had been launched. The manoeuvre he was flying appeared to be a practice 'final glide' which is normally a high speed arrival at the end of a competition flight. There was no competition in progress that day and the pilot was not engaged on any specific task.

Radio procedures

Both aircraft were equipped with VHF radios and both were selected to the correct frequency, but club staff did not hear any calls from either aircraft. The only requirements in force at the time on the use of radio was a mandatory call to be made when about to enter the Common Traffic Advisory Frequency (CTAF) area. The CTAF at Tocumwal is larger than normal with a radius of 15 NM and, if GKT had remained inside that area, there was no mandatory requirement for the pilot to make a radio call. However the AIP states that when arriving or departing from an aerodrome, pilots of radio equipped aircraft must monitor the CTAF and use their discretion in making other than the mandatory calls to assist other traffic.

There was a local procedure in force that required the tug pilot to make a 'tug rolling' call just before beginning the take-off. Although in this cast the call was made only a few minutes before the collision, no response was heard from the pilot of GKT.

Significant Factors

  1. There were no established radio procedures specifically for gliders entering the circuit area within the Tocumwal CTAF.
  2. The pilot of GKT entered the area above the circuit, unannounced at high speed.

Safety Action

As a result of the investigation into this occurrence, the Bureau of Air Safety Investigation made the following recommendation to the Civil Aviation Safety Authority in conjunction with the Gliding Federation of Australia on 13 August 1997:

The Bureau of Air Safety Investigation recommends that the Civil Aviation Safety Authority in conjunction with the Gliding Federation of Australia;

  1. establish a protected circuit area around airfields that have considerable gliding activity;
  2. establish a procedure that all inbound aircraft be required to make an all-stations radio call advising their intention to enter the protected circuit area mentioned above;
  3. apply a speed restriction of 80 kts indicated airspeed to gliders operating in this protected circuit area at all times other than during official competition events (aircraft other than gliders should operate at minimum safe speed within the area); and
  4. investigate the benefit of the application of high-visibility markings for all Australian registered gliders.

Gliding Federation of Australia response

An initial response was received from the Gliding Federation of Australia (GFA) on 12 September 1997, rejecting all but the last recommendation. A further response was received from the GFA on 9 October 1997. The response stated in part:


  1. The GFA recognizes that the rate of mid-air collisions involving gliders is unacceptably high in the circuit areas of aerodromes and will implement measures to improve discipline in flying the pattern and making better use of the radio.
  2. The GFA is unwilling to accept the imposition of mandatory radio for gliders in an area where it is optional for all other traffic.
  3. Although it is, on the face of it, difficult to argue with the recommendation for a speed limit for gliders, there are considerable numbers of fast homebuilt aircraft such as the Long Eze which have a frontal area not much different from that of a glider and are thus just as difficult to see. In fact, because of their shorter wingspan, they have even less frontal area in some cases. Given that the Tocumwal accident occurred above the circuit area and there are no other accidents on record where high glider speed in the circuit was shown to be a factor, there is no justification for the recommendation.

    In spite of the above comment, GFA will closely examine the feasibility of requiring in future that any "abnormal" circuit entry, be it a high-speed entry or an inadvertent entry from an unusual position, be preceded by an "all stations" call from a radio-equipped glider, warning other traffic of the glider's position and intentions. In the case of a non-radio glider, a high speed circuit entry will not be permitted (except at a NOTAMed contest) and pilots "caught out" by conditions and entering from unusual positions must fly so as to avoid other traffic in accordance with the CARs.
  4. A shift in emphasis is needed in cross-country training, from the euphoria of completing the task to a positive concentration on the complex circuit-joining task ahead and its consequent need for a full lookout scan and any radio calls that may be appropriate. For all joining traffic, whether from cross-countries or not, the concept of a "wake-up call" when about to enter the circuit area must be developed and we are working on that.
  5. A strategy needs to be devised to cope with the increasing complexity of cockpit instrument systems, especially when entering known busy traffic areas.
  6. BASI has identified the phenomenon of "skill fatigue", one of the symptoms of which is fixed vision and a failure to scan the sky. Given that the complex nature of many gliding tasks makes skill fatigue a likely factor in our sport, there will be an education campaign warning of the need to "keep something in reserve" for the complex task of joining a known busy part of the sky after the relatively low-risk enroute task which has just been flown.

    I trust this explains and summarises the GFA position on this matter".

Response classification: CLOSED - PARTIALLY ACCEPTED

GFA/BASI Meeting

Subsequently a meeting between BASI and the Director of Operations of the GFA was held on 13 January 1998. The following is a summary of the outcomes of that meeting:

  1. The proposal for a protected area around aerodromes with significant gliding activity was not supported. Instead it was agreed that the size of the CTAFs at these locations be reduced from a non-standard 15 NM radius to the standard 5 NM radius.
  2. It was agreed that the GFA recommend a circuit entry broadcast become a standard operational procedure for all radio-equipped gliders that, due to variation in conditions or unforeseen circumstances, can not enter or comply with the standard traffic pattern for that location. The GFA publication "Airways and Radio Procedures for Glider Pilots" to be amended accordingly. It was also agreed that a procedure would be developed for non radio-equipped gliders to follow in similar circumstances.
  3. The recommendation for an 80 kt speed restriction to gliders operating in the circuit area was rejected. An alternative course of action to address this issue, as suggested by CASA, was the avoidance of abrupt vertical manoeuvres in the circuit area. It was proposed that BASI discuss with CASA the incorporation of the avoidance of abrupt vertical manoeuvres in the circuit area, into the relevant section of the Aeronautical Information Publication.
  4. The GFA expressed a willingness to participate in any additional study to investigate the benefit of high-visibility markings on gliders. BASI will encourages the GFA and others to continue research on this subject.

Civil Aviation Safety Authority response

A response was received from the Civil Aviation Safety Authority (CASA) on 19 September 1997. This response disagreed with some of the recommendations and instead suggested some alternatives.

Following the GFA/BASI meeting, a copy of the letter to the GFA, summarising the agreements reached at that meeting, was sent to CASA.

The following response was received from CASA on 6 April 1998:

"Thank you for your letter of 3 February 1998 with the results of a meeting between BASI and the GFA at which the BASI report on the Tocumwal and Horsham glider mid air collisions were discussed.

CASA concurs with the recommendations resulting from this meeting and will instigate action to implement the reduction in the size of the Tocumwal and Benalla CTAFs".

Response classification: CLOSED - ACCEPTED


As a result of this occurrence, Sportavia Soaring Centre of Tocumwal, wrote to BASI on 27 August 1997, advising:

"Having read your Air Safety Recommendation on No R970092, we are in full agreeance with the report and also fully agree with the recommendations put forward.

It is our intention to implement immediately the recommendations outlined in the report: They are:

  1. A mandatory 15nm inbound radio transmission by all gliders.
  2. A 3nm inbound transmission by all gliders entering the circuit area.
  3. A radio call on executing the circuit entry.
  4. 80 knots indicated airspeed maximum for all gliders inside the circuit area, except during official competitions.
  5. The circuit is defined as below 2000 AGL and 3nm radius.

We believe these actions will reduce the possibility of a repeat accident of this nature. Trusting that this is to your satisfaction".

General details
Date: 05 January 1997   Investigation status: Completed  
Time: 1735 hours ESuT    
Location   (show map): 2 km NW Tocumwal    
State: New South Wales   Occurrence type: Airborne collision  
Release date: 01 January 1999   Occurrence category: Accident  
Report status: Final   Highest injury level: Fatal  

Aircraft 1 details

Aircraft 1 details
Aircraft manufacturer Let National Corporation  
Aircraft model Blanik  
Aircraft registration VH-GVS  
Serial number 174818  
Type of operation Gliding  
Damage to aircraft Destroyed  
Departure point Tocumwal, NSW  
Departure time 1728 hours ESuT  
Destination Tocumwal, NSW  
Crew details
Role Class of licence Hours on type Hours total
Unknown Student/Passenger 0.5 100

Aircraft 2 details

Aircraft 2 details
Aircraft manufacturer Alexander Schleicher Segelflugzeugbau  
Aircraft model ASW-24  
Aircraft registration VH-GKT  
Serial number 24006  
Type of operation Gliding  
Damage to aircraft Destroyed  
Departure point Tocumwal, NSW  
Departure time 1117 hours ESuT  
Destination Tocumwal, NSW  
Crew details
Role Class of licence Hours on type Hours total
Pilot-in-Command Foreign 2207
  Crew Passenger Ground Total
Fatal: 3 0 0 3
Total: 3 0 0 3
Last update 13 May 2014