The sea fog trap
On 21 February 2019, at Abbeville airfield, the weather situation was characterised by a strong anticyclone centred over France. The air mass was stable and a large area of mist or fog with stratus affected the Channel and the Strait of Dover.
bea.aero/accident-de-lulm-jmb-aircraft-vl3-b-identifie-80afq.
The low cloud ceilings pushed inland from the Baie de Somme as far as the Boulonnais (Opal Coast), the Calaisis and the Audomarois (Saint-Omer), in the form of a sea fog intrusion characteristic of these coastal regions. The automatic stations at Cayeux-sur-mer and Abbeville are representative of the situation at 4:30 pm. Members of this flying club, who were in various towns in the area, reported the sudden arrival, between 4:15 pm and 4:45 pm, of a marked sea fog bank, from the ground up to about 1 000 ft above ground, advancing rapidly like a "huge wave".
At 4:05 pm, a pilot who owned a 3-axis microlight, aged 70, holding a basic certificate from 2015 and a 3-axis microlight licence from 2016, took his VL3 B out of the hangar for a local flight. The hangar opening faces east and, in that direction, the weather was very fine, with a blue sky. A pilot coming from England and heading for Le Touquet, faced with this sea fog, was diverted by the controller to Abbeville, which was still clear, and quickly joined a straight-in approach for runway 20.
On short final, he saw the VL3 B 80AFQ lining up on runway 02. He went around to the left to fly a short circuit for runway 02, and he does not recall any radio call from the pilot of that aircraft.
At 4:32 pm, the owner of a VL3 B took off from runway 02. The diverted English pilot was then on a close downwind leg and saw the VL3 B enter a thin layer of stratus. After about 20 seconds of level flight at an altitude of 700 ft, the VL3 pilot began to descend, then started a descending half-turn, presumably to return to the aerodrome. He was then very probably flying in mist with the sun in his face for much of the turn. About 2,30 minutes after take-off, he collided with trees in almost level flight, broke up and hit the ground 4 km west of the aerodrome. The impact energy was high and the pilot died.
When the English pilot arrived at the parking area, fog was engulfing Abbeville aerodrome.
Our own perception of risk is not always optimal, through lack of experience or knowledge; these are possible gaps in our perception of the reality of the risk. They are judgement biases that affect most pilots, often through overestimating their abilities, and they may feel they can control everything, whatever happens. Limited experience of this weather situation can also lead to a bias of underestimating the risks.
To conclude, the VL3 B pilot took off just as the mass of stratus was arriving over Abbeville. This is the heart of the human factor and of our natural tendency, to a greater or lesser degree, to underestimate risks. At that time of day, all available weather information, including the Le Touquet METAR and TAF and the TEMSI chart, was unfavourable for a local VFR flight; it would have taken very little for this pilot to become aware of it.
Happy flying!
