ASN Wikibase Occurrence # 226444
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Narrative:The 2 occupants departed from their home base located at EBML (Maillen airfield) for a pleasure navigation flight to EBBZ (Buzet airfield).
|Saturday 22 June 2019
Zenair CH 601 XL Zodiac
| 62 AUO
|Fatalities: 2 / Occupants: 2
|0,5 km from Pont-à-Celles/Buzet Airfield (EBBZ) -
|Assesse-Maillen ULM Airfield (EBML)
|Pont-à-Celles-Buzet ULM Airfield (EBBZ)
| Accident investigation report completed and information captured
During the final landing approach, on a straight path to the EBBZ runway 33, the aircraft fell down vertically and impacted the ground at 515 m ahead from the runway threshold. According to witness, the loss of control of the ultralight aircraft was preceded by a sudden nose-up attitude and movement to the right, directly followed by a stall and a spin from the right wing at low altitude. The two occupants were fatally injured.
Witnesses reported having heard and seen the activation in flight of the emergency ballistic parachute
recovery system, but without any safe result.
Findings as to causes and contributing factors:
- The accident resulted from a clockwise helical descent (incipient spin) of the aircraft in stalled condition during the landing approach at low altitude.
- This happened further to a sudden pitch-up movement initiated by the pilot flying, probably in order to increase the height of the aircraft at low speed without an adequate engine power management. [direct cause]
- As the investigation showed that the parachute was activated by the cockpit handle and that an inadvertent activation is very unlikely due to a.o. the layout, location in the cockpit and the forces required, it was concluded that the parachute deployment was a reaction and not the cause of the initial stall.
- the absence of flaps extension could have led the pilot, used to land with flaps extended, to inadvertently reduce the stall speed margin. [contributing factor]
- The righthand incipient spin is a consequence of an asymmetric stall where the righthand wing stalled first. The most probable reason here for is a pilot-induced yaw to the right in order to compensate for a drift of the aircraft due to a righthand crosswind. However it could not be completely excluded that the deployment of the parachute, which was not correctly installed, didn’t negatively contribute to the (already) stalled condition by putting the aircraft attitude in an even more undesirable situation. [contributing factor]
- However as the stall happened on low height (+- 30 m above the ground) it is very unlikely that it could be recovered without parachute but with standard recovery techniques (power off, ailerons neutral, opposite rudder, relax back-pressure on stick) only. Stall recovery altitude test indicated in the AFM vary from 20 to 25 m with flaps up. But this is in a test environment with experienced test pilots and where there is no surprise or startle effect.
- The upsloping runway could have created the illusion to the pilot that the aircraft was higher than it actually was, leading to a lower approach [contributing factor]
- The long extended landing circuit performed above a landscape with a continuous variation of elevation to the runway threshold probably required a constant aircraft height adjustment with pitch and power management. Together with the crosswind continuously to be compensated for this certainly increased the workload of the pilot flying. [contributing factor]
- Both occupants had rather low flying experience on ultralight aircraft. Next to that a big difference with general aviation aircraft is the effect very quick changes in power can have on aircraft speed. [contributing factor]
- The route followed by the aircraft, in particular the infringement into the CTR of EBCI, is an indication that the crew was not at ease for the navigation from EBML to EBBZ. This might have played a role during the final approach to EBBZ. [contributing factor]
|3 years and 6 months
| Final report
|Updated [Location, Nature, Destination airport]
|Updated [Time, Departure airport, Source, Embed code]
|Updated [Aircraft type, Embed code]
|Updated [Aircraft type, Narrative]
|Updated [Registration, Operator, Nature, Source, Narrative]
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