Can I request a FWA to avoid using sick or vacation time?

No. Flexible work arrangements are not intended to be used as an alternative to, or in conjunction with, leave as provided for in Chapter 6 of Section 3342 of the Administrative Code. In addition, if an employee is participating in a FWA, any sick or vacation time taken during such arrangement will be deducted based on the FWA in place at the time used.