FAA employees participate in a demonstration of an airline cabin filling with smoke, in a simulator at the FAA Civil Aerospace Medical Institute in the Mike Monroney Aeronautical Center, Thursday, Oct. 17, 2019, in Oklahoma City. Federal researchers, using 720 volunteers in Oklahoma City, will test whether smaller seats and crowded rows slow down airline emergency evacuations. (AP Photo/Sue Ogrocki)

Richard DeWeese, Supervisor of the Aeromedical Engineering Sciences Section at the FAA Civil Aerospace Medical Institute, exits a smoke-filled simulator during a demonstration at the Mike Monroney Aeronautical Center, Thursday, Oct. 17, 2019, in Oklahoma City. Federal researchers, using 720 volunteers in Oklahoma City, will test whether smaller seats and crowded rows slow down airline emergency evacuations. (AP Photo/Sue Ogrocki)

Stacey L. Zinke-McKee, a medical-research official at the Federal Aviation Administration facility in Oklahoma City, answers a question in front of an aircraft simulator Thursday, Oct. 17, 2019, in Oklahoma City. Federal researchers, using 720 volunteers in Oklahoma City, will test whether smaller seats and crowded rows slow down airline emergency evacuations. (AP Photo/Sue Ogrocki)

Members of the media participate in a demonstration of an airline cabin filling with smoke, in a simulator at the FAA Civil Aerospace Medical Institute in the Mike Monroney Aeronautical Center, Thursday, Oct. 17, 2019, in Oklahoma City. Federal researchers, using 720 volunteers in Oklahoma City, will test whether smaller seats and crowded rows slow down airline emergency evacuations. (AP Photo/Sue Ogrocki)