Multiple investigative committees, including of the KLM and the
Dutch Ministry of Transport travelled to the crash site for investigation. The disaster was investigated by Dr.
Hendricus van der Maas, head of the Aircraft department of the RSL (Rijks Studiedienst voor de Luchtvaart, 1919–1937). He arrived at the scene of the accident on 26 December. On 8 January he made his first report to the Luchtvaartdienst (LVD). Subsequent written reports were not published. The “Permanente Ongevallen Commissie” (POC) of the RSL was adjusted on 7 February 1935 and came under the leadership of Vice Admiral
jhr. George Lodewijk Schorer. Beekman initially refused to start the flight. He did not trust the plane and was tired. During an earlier test flight to Cairo, he encountered heavy weather on the way back over the Ardennes. The airplane was controlled only with great difficulty by the two experienced pilots: Beekman and Sillevis. The flying characteristics of the DC-2 had previously given rise to research, including into the functioning of the rudder. Eventually Beekman started the flight against his will. Beekman is said to have been under great pressure to complete the flight in record time. It is remarkable that 10 hours before the plane crashed, strangers inquired whether the plane had already crashed.
Technical report (Schroder) In April 1935, a special committee, led by vice admiral
jhr. George Lodewijk Schorer, made public the technical report. The conclusion was that a multiple factors caused the crash. The bad weather, Beekman's fatigue and the poor flying characteristics of the aircraft all contributed to the crash. No further details were given. According to this report the pilot could not be held responsible for the accident. While he was in Cairo “tired and even a bit dazed“ with doubts if he was “mentally fit enough for the difficult flight”; he couldn't be blamed he was ordered by KLM to make a quick forced flight or would otherwise be fired. The difficult controllability of the aircraft in heavy weather was known by the KLM management. While Beekman was an experienced pilot, he had twice lost control of the aircraft in an earlier flight from Cairo in heavy weather. According to the report, it was expected that such conditions were also to be expected on this flight. The multiple desired adjustments to the aircraft were not made by the KLM due to “time constraints”. Second pilot Van Steenbergen had only made 10 flight hours in this aircraft, according to American regulations, this is insufficient for such a flight. Due to the shortcomings in the preparation and the risks taken, for a flight that had to be completed in record time, it was according to the report, irresponsible to allow passengers on this flight. After the crash, the committee concluded the KLM had destroyed multiple important documents, including Beekman's report on the flight characteristics of the aircraft and the report of the meeting about it; where Beekman's cupboard was first broken open. Next to the KLM the
Minister of Infrastructure and Water Management Jacob Kalff is blamed. He had given out a certificate of airworthiness for the aircraft with fewer demands than desired due to the “major interests of KLM” and should not have issued a passenger permit. The six demands requested by the minister in return for giving out the certificate were not implemented by KLM. ==Legacy==