Source: MEC Web site

What does Senior Designated Reserve Mean?

The Senior Designated Reserve (SDR) is the most senior Flight Attendant that is projected to be on Reserve for a given bid month. The company each month for each Domicile, takes into consideration flight schedules, manpower, holidays, transfers, time of year and any other pertinent factors and then calculates an estimated seniority date of which they believe will be the most senior Reserve.

The approximate SDR date for each domicile is also calculated by assuming no Lineholders will bid into the qualified purser and language lines. As stated in Section 10.A.5 of our Contract, it is recommended that the most Senior Designated Reserves and the most junior Lineholder of the same letter should preference both line and Reserve positions.