You can trade your reserve (A/B) letter once a year. A few tips were published in the recent Onboard Updates:

• You can check your A/B letter on the domicile seniority list by either:

1. on SkyNet by: - Going to Flight Attendant Scheduling and Support's home page and clicking on “Flight Attendant Seniority List;” or
2. Checking your Unimatic VACBID or LOFBID screen.

• Your A/B letter may not change from 2004 to 2005.
• The reserve letter year begins in February, not January, so if you want to trade your 2005 letter, make your trade effective February or later.
• Use DIS*27871 to submit your A/B letter trade request to your schedule planner.
• Enter your domicile in the space above “Reserve Letter Trade Request” on DIS*27871.
• Submit your trade before the first schedule day of the month prior to the month you want the trade to take effect. If you want to trade your February letter, your planner needs your reserve letter trade request no later than 1700 Central time Dec. 30.
• You can't self-trade reserve letters. Your planner won't accept a reserve letter trade request that isn't between two flight attendants.
• The flight attendant you trade with must be based in your domicile.
• Each planner determines a seniority cutoff date for A/B letter trades. You can trade A/B letters if you are junior or senior to the date, but your partner must be on the same side of the date as you are. You can't trade A/B letters with someone who is junior to the cutoff date if you are senior, and vice versa. This prevents the domicile population from becoming unbalanced.
• You can not trade reserve letters with a flight attendant who is on furlough or a leave of absence.
• You will receive a meter in your company mailbox advising whether your trade is accepted or rejected.
• You can call your planner at 800-FLT-Line option 5 between 0800-1700 Central time to verify that they received your completed trade request.

According to United: "By following these guidelines, you help planners process and respond to your A/B letter trade requests quickly, and ensure that you have the best chance of making the most of your vacation."