The procedure of returning a rescued airman back to England or sent back to the US to be rotated to another therater of war will not be covered in B-26. It could take several weeks or months for a rescued airman to return to England and in B-26 it will be simplified as follows and not entirely historically correct:

Roll D6 for the number of weeks (1 to 6) it will take for the airman to return to England, and then another D6 to see if he will return to the group or be sent to the US for another assignment; 1-4: The airman stays with the group and will become a member of another crew, eg. the Player’s crew. 5-6: The airman is sent to the US.