1930's air mail from Switzerland

A registered air mail letter from Zürich, Switzerland to Helsinki, Finland 18.3.1935. No direct air mail connection was available at the time the letter could probably have travelled the route Zürich -> Amsterdam -> Stockholm -> Turku -> Helsinki as that route had some special night postal  flights at least partially through the chain. The letter was received 18.3. but stamped for the postal flight at eight o'clock the following day (presumably when the flight took off). 

Rate for letters abroad was 30 rappen, registration fee was another 30 rappen and air mail surcharge abroad was 10 rappen for each beginning 20 grams of weight. The postage stamps (Michel 285, 286 published February 1935 and Pro Juventute 1934 stamps Michel 283, 284) add up to 70 rappen which is the correct rate. The backside of the cover has an  arrival time 21.3.1935 at 19 o'clock so it's fairly obvious there were one or more plane switches during the travel.

A postcard from Jungfraujoch to Meiringen 17.9.1935. International glider plane event took place in Switzerland's Jungfraujoch (in the Swiss Alps) between 4-18.9.1935 and had participants from at least Switzerland, Austria, Yugoslavia and Germany. During the event, gliders took off from a saddle-like area between two mountain peaks towering over four kilometres and at least some of the gliders also delivered mail special to this event. This postcard was supposed to have been sent in 16.9.1935 but due to adverse weather condition the glider flight took off the next day (17.9.1935). During the event the rate for postcards was deemed to be 1 franc - which is nicely covered a block of four 25 rappen postage stamps (Michel 180z, published in January of 1934).

The glider flight to Meiringen was a distance of 26 kilometres and was performed by Herman Schreiber - a Swiss aviation pioneer (born 1903, died 2003). Schreiber was a machinist, an engineer and an avid aviation enthusiast and he had already earlier during the event performed a glide to Bellinzona over 90 kilometres away with a glide plane (S-18 plane having a 14½-metres wing span) thus becoming the first person in the world to have crossed the Alps with a glider plane.  The next year this performance won him the Olympic gold medal in aviation - a sport that has never before and never since been represented in the Olympics and thus Schreiber is the only aviation Olympic gold medallist ever. Later on life he became known as a military flight instructor, aviation accident investigator and a pilot specialized in extremely difficult piloting missions all over the world.

Schreiber had 5500 postcards aboard during this glide flight to Meiringen. This postcard depicts the city of Zürich.