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Archive photo of the aircraft involved. (Source: Texel International Airport)
Archive photo of the aircraft involved. (Source: Texel International Airport)

Loss of control after opening of canopy, near Kornhorn

Status : Closed

On 13 February 2021, the Aerospool Dynamic WT9, a microlight aircraft (MLA), took off from Drachten Airport for a local VFR flight. The pilot was the only occupant. Near Kornhorn, the aircraft lost altitude and crashed. Shortly afterwards, the aircraft caught fire. The pilot was fatally injured. The plane was destroyed as a result of the impact and subsequent fire.

Loss of control after opening of canopy

Investigation revealed that the cockpit canopy had opened during the flight. The pilot then lost control of the aircraft and the subsequent rapid descent could not be recovered given the relatively short time before the microlight aircraft (MLA) hit the ground. What caused the pilot to lose control, remains unknown.

It is most likely that the canopy was not properly closed before the aircraft took off. On the Aerospool Dynamic WT9 type, unexpected opening of the canopy had happened several times before. The manufacturer published a mandatory service bulletin for this in 2008 requiring a change in the Pilot’s Operating Handbook. This change addressed emergency procedures to be followed by the pilot in case of inadvertent opening of the canopy during various phases of flight. In 2019, the manufacturer also recommended the installation of an upgraded canopy locking device with safety hook and sensor to prevent the canopy from opening unintentionally. 

The flying club, as holder of the MLA, was not aware of the information in the mandatory service bulletin. Regular maintenance and inspection by the holder of the aircraft and its documentation did not reveal these issues. A previous canopy incident with this aircraft encountered by a member of the flying club did not raise awareness of this hazard due to a loose safety culture within the club and the lack of a proper safety reporting system. At the time, tasks and responsibilities, especially in the areas of maintenance, instruction and safety, were not properly assigned.

Inspection and enforcement of MLA aviation is not a priority for the Dutch Human Environment and Transport Inspectorate. As a result, it was possible that the Special Certificate of Airworthiness (S-BvL) was issued without checking whether the conditions of the mandatory service bulletin were met. This was also not checked during the renewal of the S-BvL.


The investigation shows that operating the latching and locking system of the canopy of the Dynamic WT9 is sensitive to errors, which may result in the opening of the canopy in flight. This has led to a number of occurrences in the past, including two with fatal consequences.

In 2019, the manufacturer had developed a new locking system to prevent the canopy from opening in flight, which included a canopy lock with safety latch and sensor. Installation of this system is not mandatory but recommended.

Because the safety risks for MLA flying is assumed to be low, there is hardly any oversight by the government. The Special Certificate of Airworthiness is issued without establishing that the MLA is actually airworthy. Therefore, the safety level of MLA aviation depends almost exclusively on the holders, private persons as well as flying schools, flying clubs and pilots of these MLA. In the opinion of the Safety Board responsibility for the flight

safety of MLA is a shared responsibility between the holders, pilots and the government. Because it is not obvious that all holders and pilots are aware of this responsibility, it is a task of the government to draw their attention to this responsibility.

To increase the safety of MLA flying, in particular with Dynamic WT9 aircraft, the Dutch Safety Board therefore makes the following recommendations:

To the manufacturer Aerospool:

1. To make the installation of the canopy lock with safety latch and sensor mandatory for all Dynamic WT9 aircraft.

 To the minister of Infrastructure and Water Management:

2. Make organizations involved in MLA flying, holders and pilots of MLA aware that they are largely responsible for the safety of MLA flying themselves and that this requires compliance with the regulations and an active fulfillment of this responsibility.


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