schengen visa is needed
like our thai crews operating into europe a schengen visa is needed for them. usually it takes 14 working days (!) which would be equivalent of 3 weeks provided that you don't have any previous application for a schengen visa which was denied.
file the application with the european country which you'll fly most (standard routes) and you'll get a schengen visa a crew member with a validity one 1 year to be renewed yearly (very easy for renewal).
good luck.