Collision with terrain involving a Stoddard Hamilton Aircraft Glastar, VH-BAQ, about 18 km north-west of Noosa, Queensland, on 12 November 2023

The occurrence

On 12 November 2023, a pilot and passenger were conducting a private, return flight in a Stoddard Hamilton Aircraft Glastar, registered VH-BAQ, from Greenfields private airstrip near Boreen Point, Queensland.

The aircraft departed at approximately 0730 local time and tracked north over Gympie, then flew to Maryborough where the pilot conducted a practice forced landing. They then followed the coastline from Rainbow Beach to the township of Teewah, before tracking west back towards the Greenfields airstrip. 

At 0901, the aircraft joined the circuit for runway 10[1] via a descending downwind leg. The pilot reported that the wind was a slight left crosswind of about 5–7 kt. The pilot recalled that they selected one stage of flap for the approach and when they turned final, they slowed the aircraft to about 65 kt indicated airspeed (IAS).

They advised that as they crossed a tree line in the runway undershoot (Figure 1) the aircraft encountered sink and in response, they twice increased the engine power. The pilot reported that, despite the increased engine power, the aircraft touched down firmly and simultaneously the aircraft was struck by a gust of crosswind, which picked up the left wing and turned the aircraft to the right towards the house.  

In response, the pilot applied full power to go-around. The aircraft became airborne, cleared a property fence, a building and then struck the top of a palm tree and subsequently collided with terrain. The aircraft was substantially damaged, the pilot sustained minor injuries and the passenger was seriously injured.

Figure 1: Approach to Greenfields airstrip

Altitude is shown in ft above mean sea level and the groundspeed is recorded in kt.

Source: Google Earth with data from OzRunways annotated by the ATSB.

Context

Pilot experience

The pilot obtained a recreational pilot licence in November 2020 and at the time of the accident had accumulated 148.4 hours of aeronautical experience, with 22 of those hours in the accident aircraft. The pilot had flown 4.6 hours in the last 90 days, all of which were on the accident aircraft and included the 1.5 hours flown on the day of the accident.

Aircraft

The accident aircraft was a Stoddard Hamilton Aircraft Glastar GS-1 (serial no. V373X) amateur‑built aircraft, which was registered for the first time in February 2001. It had a Subaru piston engine and the aircraft’s annual inspection had been conducted approximately 6 weeks prior to the accident. 

Weather

Meteorological data recorded at the closest airport – Sunshine Coast (about 36 km to the south‑east) was provided by the Bureau of Meteorology. The 0900 METAR/SPECI report indicated that there was a light wind of approximately 7 kt from 110˚ at the Sunshine Coast Airport around the time of the accident. 

Flight data

Flight data obtained from OzRunways, recorded the time, aircraft location, altitude and groundspeed several times per minute. 

This data identified that the aircraft joined downwind at approximately 853 ft above sea level[2] while descending at 108 kt groundspeed[3] (Figure 1). The aircraft subsequently turned base at 427 ft and slowed to 71 kt. The groundspeed when the aircraft turned final was approximately 62 kt and during approach, the speed continued to reduce. The speed as the aircraft crossed the tree line was approximately 55 kt, with the aircraft crossing the threshold at 49 kt.

During the go-around, the speed reduced from approximately 50 kt to between 40–44 kt until the aircraft struck the tree (Figure 2).

The ATSB was unable to verify the windspeed and direction at Greenfield airstrip. However, the windspeed at Sunshine Coast Airport was consistent with the pilot’s report of 5–7 kt, although there was about a 90° difference in wind direction between that recorded at the Sunshine Coast and the direction reported at Greenfield by the pilot. 

Figure 2: Missed approach and track divergence

Source: Google Earth with data from OzRunways, annotated by the ATSB

Approach procedure

The pilot operating handbook (POH) for the aircraft recommended a normal approach speed of 65 kt IAS slowing to 60 kt over the threshold. It also advised that the aircraft can be ‘landed with no flaps, half flaps or full flaps but the recommended speeds remained the same’. The POH also noted that ‘at slower airspeeds, the power-off sink rate increases rapidly’.

The published stall speed for the aircraft varied between 43–49 kt IAS, depending on whether flaps were retracted or fully deployed.

Go-around procedure 

The go-around procedure from the POH required the addition of full power and a speed of 65 kt IAS to ‘achieve the best angle of climb when clearing obstacles’. 

Decision making 

The Federal Aviation Administration’s (FAA) publication The art of aeronautical decision-making advised that aviation decision making can be broken down into 3 parts - perceive, process and perform. In addition, the FAA publication Airplane flying handbook Chapter 18 Emergency procedures advised that a pilot takes about 4 seconds to perceive and react to an emergency situation.

Accident site

The ATSB did not attend the accident site and therefore did not conduct a detailed inspection of the wreckage. However, photographs of the site (Figure 3) were provided to the ATSB and they showed:

• damage to the nose cone, with the propeller largely detached from the engine
• substantial damage to the cockpit windshield
• damage to both wings from contact with terrain. 

Figure 3: Aircraft damage

Source: Pilot, annotated by the ATSB

Safety analysis

During the final approach with one stage of flap selected, the aircraft’s speed reduced to a groundspeed of 56 kt and reportedly as the aircraft flew clear of a line of trees, it encountered unexpected sink. While that was possibly influenced by wind/terrain interaction at the low operating height, it was also consistent with the POH advice of increased sink at reduced airspeed. As the approach continued, despite reported engine power increases, the speed continued to reduce with the aircraft crossing the threshold at approximately 49 kt groundspeed. As there may have been some headwind component (consistent with the wind speed and direction at Sunshine Coast Airport), the indicated airspeed (IAS) may have been higher than this value, but probably below the recommended 65–60 kt during the final stages of the approach and crossing the threshold. 

On touchdown the aircraft reportedly encountered a left crosswind gust that the pilot was unable to counter, resulting in the aircraft turning right towards the house to the south of the runway. 

It is likely that the pilot was surprised by divergence as, although they applied full power to conduct a go‑around, they did not realign the aircraft with the runway, resulting in the aircraft becoming airborne heading towards obstacles. A pilot’s decision making can take up to 4 seconds to perceive and react to an unexpected action and in this time frame the aircraft had travelled towards the obstacles.

As the aircraft likely became airborne at less than the best angle of climb airspeed, V_X (65 kt IAS) the available climb performance was relatively poor and due to the immediate proximity of obstacles, there was limited ability to accelerate to V_X via a shallow climb profile. Consequently, the aircraft’s speed and height remained low, resulting in the aircraft striking the top of the tree close to the stall speed, before colliding with terrain.

Findings

From the evidence available, the following findings are made with respect to the collision with terrain involving a Glastar, VH-BAQ, about 18 km north‑west of Noosa, Queensland, on 12 November 2023.

Contributing factors

• On touchdown the aircraft reportedly encountered a left crosswind gust that turned the aircraft towards obstacles to the south of the runway. 
• During the go‑around, the aircraft was not realigned with the runway and the best angle of climb airspeed was not achieved, resulting in a collision with terrain.    

Sources and submissions

Sources of information

The sources of information during the investigation included:

• the pilot  
• recorded data from the GPS unit (OzRunways) onboard the aircraft.
• Bureau of Meteorology 

References

Federal Aviation Administration 2004, Airplane Flying Handbook, Chapter 2-14, page 53, United States Department of Transportation.

Martin, WL, Murray, PS & Bates, PR 2012, The Effects of Startle on Pilots During Critical Events: A Case Study Analysis, Brisbane, Griffith University.

Stoddard-Hamilton Aircraft, Inc. 1998, GlaStar Model GS-1 Tricycle Gear Owner's Manual, P/N 063-02001-01, Stoddard-Hamilton Aircraft, Inc., Arlington, WA.

Submissions

Under section 26 of the Transport Safety Investigation Act 2003, the ATSB may provide a draft report, on a confidential basis, to any person whom the ATSB considers appropriate. That section allows a person receiving a draft report to make submissions to the ATSB about the draft report. 

A draft of this report was provided to the following directly involved parties:

• the pilot
• Civil Aviation Safety Authority 

No submissions were received.