When a Southwest Airlines flight attendant entered the cockpit during a flight and saw an iPad showing what appeared to be live footage from the plane’s lavatory, one of the pilots assured her it was a “top secret security measure,” according to court documents. Now, the airline denies there was ever a camera at all.

The flight attendant, Renee Steinaker, sued Southwest Airlines last year for emotional distress, negligence, invasion of privacy and sexual harassment. But on Saturday, the airline said it would “vigorously defend the lawsuit,” claiming that it had investigated the allegations at the time of the alleged incident, in February 2017, and had found no hidden camera.

“We can confirm from our investigation that there was never a camera in the lavatory,” Southwest Airlines said in a statement. “The incident was an inappropriate attempt at humor, which the company did not condone.”

Ms. Steinaker, who has worked as a Southwest flight attendant for decades, originally filed the lawsuit in 2018 in Maricopa County, Ariz., before the case was moved to Federal District Court in August, according to her lawyers.