In Bcbp::date_of_issue_of_boarding_pass the Julian day is documented as starting at '1' whereas the Leg::date_of_flight is documented as starting at '0'.
You misinformed
Fields "date of flight" and "date of issue"
date of flight: 001 = Jan 1st, 365 = Dec 31st,
date of issue: 6001 = Jan 1st 2006, 6365 = Dec 31st 2006
In Bcbp::date_of_issue_of_boarding_pass the Julian day is documented as starting at '1' whereas the Leg::date_of_flight is documented as starting at '0'.