I sent this question to Brian Asquith in the UK, who is an expert on Chinese Airmails. He in turn sent it to Egil Thomassen in Norway. The following is the exchange of emails between the three of us:

Email from Brian Asquith to Egil Thomassen â€" 15 Feb. 2013

I received this email from Ken Sanford and would have thought that you were the ideal man to answer him. Do you know Henning Mathiassen who apparently lives in Norway.

According to a splendid book "Norwegian Air Mail" written in immaculate English by one Egil Thomassen on p. 169 states that
China
1) 1926 air mail to China could be sent via Berlin-Manchouli and trans-Siberian railway.
(BLA) The Eurasia airmail route from Irkutsk to Shanghai had been cancelled by 1933.
2) From 1st December 1932 the air mail to Southern China was directed via the Marseilles-Saigon route.
(BLA) The cover sounds to be directed to Hong Kong which I would regard as Southern China (it would be nice to see a picture of the cover). Why would the mail be directed via Air France rather than Imperial Airways?.

You state on the same page that the rate was 160 but the email says you had to add 30 ore to postage making 190 and only 145 has been paid.

Can you help at all?

Email from Egil Thomassen to Brian Asquith â€" 16 Feb. 2013

A solution may be this:
The international "Liste generale de services aeropostaux", date May 1932, state that airmail from Norway to Hong Kong carried with the French Marseilles-Saigon route ha to be paid with international rate 30 øre + airmail rate 160 øre = 190 øre. The cover in mention has not been paid for the French route (the post clerck in Arendal may not have been updated, or other reasons) and hence the cover was sent via Berlin and Siberia. That will explain the 16 days between transit in Berlin and arrival in Hong Kong. If the intention had been to send the cover with the French route, Norway Post would have sent the cover with railways to Malmø (Sweden) for forwarding by air to Paris and Marseilles. No idea sending it to Berlin then.
The airmail rate to China via Siberia (or to Siberia itself) was 100 øre. Why 45 øre was added I can not explain, but an airmail cover to Russian Europe was 45 øre.

Email from BrianAsquith to Ken Sanford â€" 16 Feb. 2013

As mentioned in my email to Egil, copied to you:-
(BLA) The Eurasia airmail route from Irkutsk to Shanghai had been cancelled, -
due to the invasion of Manchuria by the Japanese in 1932, changing the name to Manchukuo.
The cover would probably have been flown by the Russo-German Deruluft airline Berlin - Moscow then by the Russian Dobrolet airline from Moscow to Irkutsk, then trans-Siberian railway to Vladivostock, From there, probably by sea to Tsingtao or Shanghai, then CNAC to destination (Hong Kong Airmails by Colonel Webb).

Email from Egil Thomassen to Ken Sanford â€" 16 Feb. 2013

The Eurasia airmail route from Irkutsk to Shanghai had been cancelled by 1933.
The cover was flown Berlin-Danzig-Köningsberg-Kaunas-Velike Luki-Moscow, and from Moscow daily route over Kasan-Sverdlovsk-Omsk-Nowo Sibirsk-Krasnojarsk-Irkutsk-Werchene Udinsk-Tschita to Chabarowsk. From Irkutsk route to Vitim and Jakutsk. From Chabarowsk route every third day to Vladivostok. I do not know how the mail was forwarded either from Irkutsk or Vladivostok through China to Hong Kong.

Regards,
Egil

This is a somewhat curious letter concerning postage as the airmail fee from Dec 1. 1932 until January 1. 1935 was 160 ore, and you had to add 30 ore standard international postage. Thus an ordinary letter up to 20 grams would cost 190 ore.
 
Then to the routing. According to circular of the Norwegian Post, postal items by airmail should be directed via the French route Marseilles to Saigon. From Saigon the mail was forwarded by boat to Hong Kong. A lot of Norwegian  air mail was sent via Berlin in the 1930ies, to be forwarded to other European destinations. This explains the Berlin postmarks. But I guess the French were getting sloppy concerning air mail letters in transit.
 
Henning Mathiassen
Norway

In my opinion, the cover would have been flown by Eurasia Airlines from Berlin to Hong Kong.

If it went via Berlin, it is unlikely that it would have been forwarded to another European city to connect to Imperial Airways.

Ken SAnford

Hi, please help to provide possible route for cover mentioned as below & tell me if U want to have cover image both face & front, thank you.

1) From: Arendal, Norway dated Dec 11, 1933 with Rate: 1Kr45
2) Transit: Sassnitz (Berlin-Sassnitz (Hafen) Bahnpost Zug18*- 13.12.33)
3) Transit: Berlin, Germany dated Dec 13, 1933
4) Arrive: Hong Kong Dec 29, 1933