Ships on the Danube destined for Black Sea forced to take Soviet pilots on board due to changed positions of minefields according to a CIA report dated 24 November 1948

An item reported that the position of the minefields laid at the Danube mouth was changed making it necessary to take Russian pilots on board at the Danube mouth who were disembarked at the arrival at the Snake Islands in the Black Sea. The item ended with the sentence: 'The new procedure for the pilots to follow had not been yet established.’

Source
The report was published on www.archive.org, document number CIA-RDP82-00457R002100110005-5