One who is I believe a Delta pilot employee reached out to me via FT Private Message to give some clarity on the possible status of the noted FA. This is my understanding:

scheduled on duty = no drinking (seems obvious enough!)

deadheading = no drinking by company policy. Deadheading is a scheduled flight at the company's convenience (back to base, or start from out-of-base); it counts toward FAA duty hour limits.

listing for the extra FA jump seat = no drinking by company policy. No drinking even if not occupying the extra FA jump seat. This is a designated crew member even if not scheduled. One might choose to list for the jump seat to have a better chance of flying than trying as non-rev.

If I have this wrong I hope others will correct me.

3Cforme - Delta Forum Moderator