In 1943 the pilot and author Clauson Kaas publishes a book entitled Danish aviators in the air. An appendix lists all then trained army and navy pilots. During the period 1935-1939 a total of 26 pilots are trained in the small Danish navy air service. I have been looking into the path taken by these pilots during the following years.
In 1945, 14 of the 26 pilots have served air forces abroad. Two in Finland, two in Germany, two in Sweden, and eight in Britain. Four of them have lost their live, and one is to die within a few years. Three have lost their lives before the war; Aviation was dangerous business even in peacetime in those days. 
I find it interesting to see, that this group of people undertake very different paths in the following years.
Finland - the Winter War 1939-1940
The Soviet Union attacked Finland on 30 November 1939. To many Danes it was an inexcusable attack on a neutral country and a sister nation. About 1,200 Danes volunteer for service in Finland, about 300 have a military background.
Of the pilot classes of 1935-1939 two pilots volunteer: 1st Lieutenants Knut Kalmberg and Jørn Ulrich (both 1938) desert in early 1940 to fight the Soviet forces. On 13 February 1940, Knut Kalmberg is shot down while attached to 1./LLv 26 (26th Squadron). Before is death Kalmberg is credited with two victories: a Tupolev SB-2 bomber on 2 February and another SB-2 on 12 February. The same day, Jørn Ulrich is wounded. 
A few days after the German occupation of Denmark, on 9 April 1940, a number of pilots begins the planning of an escape to Britain, some of them with the initial intention to fight in Norway, though.
On the night between 16 and 17 April 1940 Flying Officers Kaj Birksted and Charles Marinus Sundby escape cross the Sound between Denmark and Sweden with the intention of joining the Norwegian forces still fighting the Germans. Kaj Birksted is to become Wing Commander in Royal Air Force and Charles Marinus Sundby joins the Royal Canadian Air Force as instructor and later transfers to Ferry Command. He is killed in an air accident in China in 1948. 
Two pilots manages to escape with Flying Officer Thomas Christian Sneum. On 21 July 1941, Pilot Officer Kjeld C.J. Pedersen and Thomas Sneum escape Denmark in a D.H. Hornet Moth. From Funen they reach Coquet Island, Northumberland, in six hours. They are met by a section of Spitfires and later Hurricanes and lands in a field outside Alnwick. Kjeld C.J. Pedersen volunteers for the Royal Air Force (87010, RAFVR) and is in service from 27 June 1941 until the end of the war. 
On 10 September 1941, Thomas Christian Sneum and army pilot Sigfred Johannes Christophersen are dropped over Denmark as SIS agent. On 28 March 1942, his security compromised, Thomas Christian Sneum and Flying Officer Arne Hroar Helvard escape to Sweden by crossing the Sound then covered by ice. They walk from the seaside town Skodsborg, but have to land on the island Hven. They are arrested by the Swedish police and imprisoned for 67 days. They manage to avoid being turned over to the German authorities in Denmark. They both manage to get to England.
Arne Hroar Helvard is accepted in the Royal Air Force (128521, RAFVR). Initially he is stationed in North Africa flying Handley Page Hampden. On 22 June 1943, he is killed in action when his 218 Squadron Stirling bound for Krefeld, Germany, is shot down at Langdorp, Belgium. 
Thomas Christian Sneum joins the Royal Norwegian Air Force in the last months of the war. 
Later in 1942, Flying Officer Niels Juul Rysensteen Buchwald manages to escape from occupied Denmark paddling the Sound between Denmark and Sweden in a kayak. In England he reports to the Danish recruiting office in London. He volunteers for Royal Air Force and is trained as fighter pilot (143462, RAFVR). On 13 October 1944, he is killed in action in his 222 Squadron Spitfire on a skip bombing and strafing mission at Schoondijke, Holland. 
Finally, Senior Lieutenants Henning Valentiner and Poul Zigler is transferred to England via Sweden in 1943-44 and servs in the Fleet Air Arm. 
Germany - Danish Officers in Luftwaffe
On 8 July 1941, an announcement from the Ministry of War permits commissioned officers of the Danish armed forces to volunteer for Frikorps Denmark (Free Corps Denmark). A number of Danish officers enlist; some of them for Luftwaffe service. Contrary to other pilots they do not need to escape.
Flying Officer Poul Sommer, later Hauptmann, is one of them. Following training he is transferred to North Africa, but returns to Denmark in 1943 becoming commander of Wachkorps der Luftwaffe in Dänemark guarding Luftwaffe installations in Denmark. He is dishonourably discharged from the Navy 25 May 1945, arrested in July 1946 and eventually sentenced to 12 year in prison. During his Luftwaffe service, Poul Sommer is decorated with Eisernes Kreuz 2. Klasse and Eisernes Kreuz 1. Klasse (Iron Cross). 
Wolfgang Rudolf Fabian too volunteers for Luftwaffe service. He is trained at Jagdfliegerschule 4 in Fürth. At the end of training, he is posted to 9./JG51. On 21 June 1942, his aircraft – Bf 109 F-2 'Gelbe 6' (Wk. Nr. 12601) – is hit by flak northeast of the town of Rzhew in Russia. Wolfgang Rudolf Fabian is killed. 
Sweden - Danish Exile Forces
On 29 August 1943, the Danish political co-operation with the German occupation forces is discontinued. During 1944 a the Danish Brigade is set up in Sweden. This include a small air force. Senior Lieutenant K. von Wylich-Muxoll and Flying Officer Jørgen Lauritsen escape from Denmark and becomes part of this force. Though equipped and trained, the force was never in combat and returned to Denmark 12 May 1945 - by train.
In September 1944 Jørgen Lauritsen is killed during a training flight. 
This article is not intenteded to explain the motives of the different pilots for joining different air forces. Only I have found the fact that they chose different paths thought provoking. Nine stayed in Denmark. For more information see individual pilot profiles.
- Clausson Kaas, 1943
- Pontoppidan, 1984
- Ancker, 2001, cnag.org
- Ancker, 2001
- Chorley, 2004, Troelsen og Sund, 2004
- Ryan, 2008
- Andersen, 1984, Franks, 2000; Reventlow, 1956
- Pontoppidan, 1984
- Ancker, 2001, Neulen, 2000
- Ancker, 2001, Neulen, 2000
- Holm, 1995