DALLAS (AP) — Southwest Airlines is backing away from a plan to put unvaccinated workers on unpaid leave. A Southwest spokeswoman said Tuesday that employees must submit proof of vaccination against COVID-19 — or request an exemption from the shots — by Nov. 24. But she says employees whose requests for vaccine exemptions haven’t been processed or approved by Dec. 8 will be allowed to keep working. Major U.S. airlines are federal contractors. Southwest, American, United and Delta all have taken slightly different approaches to complying with President Joe Biden’s order that federal contractors require employees to be fully vaccinated by Dec. 8.