Uruguay Cover To Germany 1937. Airmail Route???

Found this cover in a lot I bought.
First I thought it went just by boat "Vapor Alcantara" Uruguay 21/6/37.
But at the back there is a receiving Bahnpost (train) mark with an airplane from Germany 22/6/37 (just 1 day after the cover was posted?)

So did the cover went by airmail and not by boat?

The Uruguay postmark is June 4. Perhaps at 21:00 hours?

Thanks John, that makes more sense ;)

Here's an old poster of the RMS Alcantara at Rio de Janeiro (from Wikipedia):

Yes, the Montevideo postmark is June 4, 1937 recorded at 2100 hours which is 9:00 PM in the evening. The German postmark appears to be a commemorative one for June 22, 1937. This would be consistent with this going by ship then land from Uruguay to Germany, though it could be possible that it went by air part within Germany once the ship docked - likely at Bremen. The "Vapor Alcantara" rubber stamp seems likely to be privately applied by the sender to ensure the cover made it through the Uruguayan post office in time to be put aboard that ship which was likely the one that the sender thought would get his mail to Germany in the fastest way without going across the Atlantic by air which would have cost more.

Here's the Bochmann entry for the German cancel.



The text on the cancel translates as "250 times over the South Atlantic / German Airmail". The remainder of the Bochmann entry notes "Only as an arrival stamp on post from South America, which arrived via Cologne."

The cancel can be found in type a-c. Yours is an "a". All three cancel varieties have the same value in Bochmann. I'll note that most cancels in Bochmann are valued pretty low (<2.00), so this appears to be more of a rarity than most. Also, Bochmann catalog values are very old, so they should only be used to determine relative value at this point.

Thank you all for the information.