Helsinki's tiny airport on the Katajanokka peninsula. Aero O/Y Ju 52 OH-ALK is in the house. Aircraft operated from the ice on wheels or skis in winter. Photo from: Finnish Aviation Museum

Delivery of Aero O/Y's second Ju 52 - OH-ALK was already put in service during 1932. These aircraft operated on floats in summer until the opening of Malmi airport in 1938. In peacetime after the Winter War on 14 June 1940, operating Aero O/Y flight 1631 from Tallinn, Kaleva was shot down by two Soviet DB-3 bombers during Soviet preparations to occupy Latvia. All nine people on board, including diplomatic couriers, were killed. This is said to have been the first commercial airliner shootdown by fighter aircraft in history. Photo by: Finnish Heritage Agency

Arrival of Charles and Anne Lindbergh in Helsinki during their remarkable seaplane trip halfway around the world. Next stop, Leningrad. Photo by: Akseli Neittamo / Finnish Aviation Museum

A neat four-seater amphibian flying boat, the prototype of the FBA 290 series paid a visit to Helsinki not long after its first flight in April 1931. HM.4 is an aircraft class code and not part of the type designation in our opinion. Photo from: Finnish Heritage Agency

Aircraft of the German Airline Pilot School (DVS) flown by Walter von Gronau. Von Gronau and crew flew it from Sylt to New York City in 47 hours in August 1930 via the Faroes, Iceland, Greenland and Labrador. Earlier it was N-25 of Roald Amundsen, see other picture, and G-EBQO used by Frank Courtney. The flying boat was preserved in the Deutsches Museum in Munich in 1932 but badly damaged by Allied bombing in 1944. Photo from: Finnish Heritage Agency

During the 1929 summer season the magazine Suomen Kuvalehti offered free rides in this aircraft at various places in Finland. The photo was taken at the start of the campaign at Helsinki's seaplane airport. Note the double (post) horn in the flag used by Aero O/Y. Photo from: Finnish Heritage Agency

Junkers F13 production ran from 1919 until 1932, then an unusually long time. K-SALG was delivered to Aero O/Y in May 1928. The aircraft was soon sent to Norway to take part in the search and rescue operations following the crash of the airship Italia. Photo by: Harald Rosenberg / Helsinki City Museum

The seaplane to Stockholm. Operated by Aero O/Y from June 1926 until June 1935. Photo by: Sophie Petersen / National Museum of Denmark