Your Supplement and local practice and the details of the situation may change how this case is handled, but according to Article 40, additional Saturday Air Work is intended first for part-timers . . .
ARTICLE 40. AIR OPERATION
Section 1 - Air Drivers
(k) Saturday or Sunday Air Work
(1) To perform Saturday or Sunday air work the Employer and the Union recognize the need for air drivers other than those regularly scheduled. Qualified part-time employees who are interested in performing this work will so notify the Employer, be certified and be placed in seniority order on a posted qualified air driver list. Such work will be first offered in seniority order to employees on the qualified list who have not worked more than thirty-seven (37) hours in the current week. This work shall then be offered in seniority order to qualified part-time employees regardless of hours worked. If the scheduling needs still cannot be met, and additional employees are needed, the Employer may force qualified part-time employees in reverse seniority order.
(2) These employees shall be paid at the air driver’s straight-time rate of pay in accordance with Section 6 below. Time and one-half (1-1/2) will be paid after eight (8) hours per day or after forty (40) hours per week.
(3) All employees working as an air driver on Saturday or Sunday under this Section shall have a three (3) hour guarantee.