In preparation for the first crewed test flights of the Boeing CST-100 Starliner capsule, four of the astronauts selected to crew the spacecraft participated in a test of the Emergency Egress System (EES). The system would be utilised should there be any dangerous circumstances identified on the lead up to a launch of the United Launch Alliance Atlas V.
NASA astronauts a Nicole Mann, Suni Willams, Bob Behnken and Boeing test pilot Chris Ferguson tested the system on June 19, 2018 at Cape Canaveral Air Force Station’s Launch Complex 41 in Florida. The ESS zip line transported the astronauts from the Crew Access Tower 52 meters (172 feet) in the air to a point 400 meters (1,300) away from the launch pad at up to 64 kph (40 mph). It is hoped that at that distance, the astronauts would be clear of any danger that they may face in an emergency.
The ESS is based on the commercially available Terra-Nova ZipRide zip line. It has many similarities with the slide-wire system utalised during the Space Shuttle program. However, with the addition of swing-like seats, officials have touted that the new system is noticeably easier to use.