Southwest Airlines plans to reduce service to and from Atlanta next year, affecting some employees on the impacted routes, the union covering the carrier's pilots said on Wednesday.

The Southwest Airlines Pilots Association said the airline would schedule drawdowns from April next year and reduce the number of gates to 11 from 18.

Southwest did not immediately respond to a Reuters request for comment.

The news comes ahead of Southwest's investor day where the company is expected to update its annual and current quarter forecast.

The Dallas, Texas-headquartered airline is facing pressure from activist investor Elliott Investment Management, pushing for an executive shake-up and reportedly telling one of Southwest's top unions that it wants to switch out CEO Robert Jordan.

CNBC first reported the news saying that Southwest was planning to cut over 300 pilot and flight attendant jobs.