http://uboat.net/boats/u30.htm
"On 29 April 1940 in the North Sea the boat rescued four crew members from a crashed German Dornier Do 18 airplane of
2nd Staffel Küstenfliegergruppe 906. The boat was already inbound to port and reached Wilhelmshaven the next day."
Date is wrong in article should be 29 March 1940 - U-30 reached Wilhelmshaven 30 Mar, 1940 - She was on patrol 29 April 1940 but did not reach her home base until 4 May, 1940