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5. Hypotheses about the Cause and Location of the Accident
    
     5.1
  Reflections on the flight of the ”Latham”


During the open hearing in Tromsø on 30 September, project developer and seaplane pilot Morten Waltinsen submitted some interesting ideas about the “Latham 47” aircraft and its characteristics as a seaplane. We will not go into detail regarding Waltinsen’s report, but rather look more closely at aspects of the aircraft, the crew, the weather conditions and the circumstances surrounding the operation itself, that may have had some significance for the fate of the flight. Technical data about the type of aircraft and assessments made by Hovdenak/Hoel and Riiser-Larsen have been included in this conclusion with regard to the flight itself

The Crew


The crew members were
French and were led by
Captain René Guilbaud,
born 1890, an experienced
pilot from the French Naval
Air Force who served his
country in World War I. The
co-pilot was Albert de
Cuverville, born 1892. The
aerotechnicians were maitre
Gilbert Georges Paul Brazy,
born 1902, and 2nd maitre
Emile Valette. The French
crew must be considered
well-qualified for the task,
even though they lacked
experience of Arctic operations.

The lack of Arctic experience was compensated by the participation of initiator and Arctic explorer Roald Amundsen and navy pilot Leif Ragnar Dietrichson. The Norwegian contribution to this operation consisted largely of planning and preparation. It is only natural to assume that neither of the Norwegians took a direct part in the actual manoeuvring of the aircraft.

The “Latham” took off from Normandy, France, at 9.05 a.m. on June 16 and flew non-stop to Bergen where it landed at 9.45 p.m. Next day, after a stopover of about 22 hours, the aircraft took off from Bergen at 8.20 p.m. landing in Tromsø at 6 a.m. on June 18. After a stop of just under 10 hours in Tromsø, they took off again at 3.55 p.m. and were last seen for certain heading in a northerly direction north of Hekkingen lighthouse.

One can only assume that the crew set off on this trip with expectations, a feeling of excitement and a certain fear of the unknown. There had been little time for planning and preparations. We do not know how many hours the crew had allowed for rest and sleep in Bergen, but due to lack of both time and support crew, it is obvious that the crew would have had to carry out most of the essential tasks themselves, including loading, research, planning, etc. The flights from Bergen to Tromsø, and then from Tromsø, took place at night. The crew had not had time to acclimatize themselves to conditions such as the midnight sun and 24-hour daylight. The stop in Tromsø from 6 a.m. until departure at 3.55 p.m. took place in an animated and stressing atmosphere where there would hardly have been ant time for rest. In all probability the crew would not have been fully rested on their departure from Tromsø and are likely to have lost track of the time of day since their last trip to Tromsø took place at night time. The midnight sun and bright nights would most likely also have been a distracting factor.

The “Latham 47” Prototype II

The French aviation industry was among the best in the world, and at the time the Latham  was a well-equipped and modern aeroplane with most of the advanced instrumentation that was available. It was primarily constructed for long-distance flights and was taken out of service on the preparations for trans-atlantic flights in order to search for the “Italia.” Plywood was used to reduce the weight of the aircraft itself, and to increase its payload capacity. For the same reason, a boat-shaped fuselage was chosen in order to avoid the increased weight and air resistance that two sturdy pontoons would represent. The compromise involved two small pontoons, one at each wing tip, designed to balance the aircraft on the water. However, during operations on the sea, when there are strong winds and considerable swell, a construction with a keel and two wing pontoons causes great strain on the wings, wing pontoons and wing fittings, particularly when the direction of the wind does not correspond to that of the waves. Under such conditions, the aircraft was probably difficult to manoeuvre on the water.

The range of the aircraft was more than sufficient for the planned distances with intermediate landings and refuelling.

The aircraft was equiped with instruments for blind flying, i.e. it could fly through areas of cloud or fog without the need for references to the ground or sea surface. However, flying with visual references to the ground/sea surface was the norm at that time. The instruments of the time were rudimentary and not the easiest to manouevre an aircraft by. Furthermore, in time they could accumulate errors and needed to be reset on a regular basis, something which normally required visual reference to the ground. Some of the instruments were retrospective, thus indicating change of course, loss of altitude and so forth, after a certain period of time had elapsed. In actual fact, the length of time the instruments could be used when flying through cloud was limited by the need to reset.

Weather conditions and daylight

The weather in the Tromsø area on 18 June 1928, was dominated by low pressure over central Scandinavia. North Norway was under the influence of a high pressure zone east of Svalbard that crossed over to the Kola peninsula. The result north of Tromsø was a north-easterly wind with fog and fog banks. The wind increased in strength further north. In the area around Bjørnøya there was a north-easterly wind and the fog had lifted and given way to hazy weather with low stratus. If we assume that the aircraft held a steady course for Bjørnøya after passing Hekkingen lighthouse, the crew would have had the midnight sun 60-70 degrees to the left of the nose of the aircraft. Low sunshine from that angle combined with fog and mist would have made visual flying conditions difficult. The horizon becomes diffuse and indistinct. It becomes difficult to find one’s bearings and to distinguish where the sky ends and the sea begins, or vice versa. The references necessary for visual flying are erased. The prevailing flying conditions were instrumental to disorientation and a false sense of the aircraft’s horizontal plane.

The radio message

If we assume that the “Latham” flew straight from Hekkingen lighthouse towards Bjørnøya after passing Hekkingen at 4.20 p.m. local time, the aircraft’s position would have been approx. 72° 30’ N, 018° E when the radio call was made between 6.45 and 6.55 p.m. The radio message mentioned nothing about technical difficulties and indirectly confirms that the flight was progressing normally and as planned. The transmission revealed difficulties with the radio connection, but this is normal and a well-known phenomenon in Arctic regions during the summer, due to varying atmospheric conditions. It is correct to assume that the flight went more or less as planned until 7 p.m.

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