The in-flight crew escape system is provided for use only when
the orbiter would be in controlled gliding flight and unable to
reach a runway. This condition would normally lead to ditching.
The crew escape system provides the flight crew with an alternative
to water ditching or to landing on terrain other than a landing
site. The probability of the flight crew surviving a ditching
is very slim.
The hardware changes required to the orbiters enable the flight
crew to equalize the pressurized crew compartment with the outside
pressure via the depressurization valve opened by pyrotechnics
in the crew compartment aft bulkhead that would be manually activated
by a flight crew member in the middeck of the crew compartment;
pyrotechnically jettison the crew ingress/egress side hatch manually
in the middeck of the crew compartment; and bail out from the
middeck through the ingress/egress side hatch opening after manually
deploying the escape pole through, outside and down from the side
hatch opening. One by one, each flight crew member attaches a
lanyard hook assembly, which surrounds the deployed escape pole,
to his or her parachute harness and egresses through the side
hatch opening. Attached to the escape pole, the crew member slides
down the pole and off the end. The escape pole provides each crew
member with a trajectory that takes the crew member below the
orbiter's left wing.
Changes were also made in the software of the orbiter's general-purpose
computers. The software changes were required for the primary
avionics software system and the backup flight system for transatlantic-landing
and glide-return-to-launch-site abort modes. The changes provide
the orbiter with an automatic-mode input by flight crew members
through keyboards at the commander's and/or pilot's panel C3,
which provides the orbiter with an automatic stable flight for
crew bailout. This software change, which is required to allow
the flight crew commander's departure, automatically controls
the orbiter's velocity and angle of attack to the desired bailout
The crew would make the escape decision at an altitude of approximately
60,000 feet and would immediately make an input to the flight
control system software autopilot mode.
When the orbiter descends to an altitude of approximately 30,000
feet, its airspeed must be decreased to approximately 200 knots
(230 mph). At approximately 25,000 feet, a crew member in the
middeck (referred to as the jump master and seated in the forward
left seat in the middeck) raises a cover on the left side of the
crew compartment middeck at floor level and pulls the T-handle,
which activates the pyrotechnics for the depressurization valve
at the crew compartment X o 576 aft bulkhead. This equalizes the
crew compartment cabin and outside pressure before the side hatch
At approximately 25,000 feet, the software for the automatic
autopilot mode changes the orbiter's angle of attack to approximately
15 degrees. This angle of attack must remain nearly constant for
approximately three minutes until the orbiter reaches an altitude
of approximately 2,000 feet.
At approximately 25,000 feet, the jump master jettisons the side
hatch by pulling the hatch jettison T-handle next to the depressurization
T-handle. When the T-handle is pulled, pyrotechnics separate the
hatch assembly by severing the side hatch hinge, and three pyrotechnic
thrusters jettison the tunnel/hatch from the orbiter at a velocity
of approximately 50 feet per second.
The jump master pulls the pip pin on the escape pole and pulls
the ratchet handle down, which permits the two telescoping sections
of the escape pole to be deployed through the hatch opening by
A magazine assembly located near the side hatch contains a lanyard
assembly for each flight crew member. Each lanyard assembly consists
of a hook attached to a Kevlar strap that surrounds the escape
pole. Five roller bearings on each strap surround the pole and
permit the lanyard to roll freely down the pole. Each flight crew
member positions himself or herself at the hatch opening and attaches
himself or herself to the escape pole via the lanyard hook assembly
and jumps out the hatch opening.
Each lanyard assembly incorporates an energy absorber rated at
1,000 pounds. The Kevlar strap consists of two sections of permanent
Nomex thread stitching and a section of breakaway Kevlar thread
stitching. When the crew member exits the side hatch on the escape
pole, the breakaway Kevlar thread stitching can break away, providing
the crew member with an energy absorber. The crew member slides
down the escape pole and off the end into a free-fall. The escape
pole extends downward 9.8 feet from the side hatch and provides
the crew member with a trajectory that will carry him or her beneath
the orbiter's left wing.
It would take approximately 90 seconds for a maximum crew of
eight to bail out. After the first crew member bails out from
the middeck, the remaining crew members follow at approximately
12-second intervals until all are out by approximately 10,000
A handhold was added in the middeck next to the side hatch to
permit the crew members to position themselves through the side
hatch opening for bailout.
The escape pole is constructed of aluminum and steel. The arched
housing for the pole is 126.75 inches long and is attached to
the middeck ceiling above the airlock hatch and at the 2 o'clock
position at the side hatch for deployment during launch and entry.
The escape pole telescopes from the middeck housing through the
side hatch in two sections. The primary extension is 73 inches
long, and the end extension is 32 inches long. The diameter of
the housing is 3.5 inches. The two telescoping sections are slightly
smaller in diameter. The escape pole weighs approximately 241
pounds-248 pounds with attachments.
On orbit, the escape pole's primary stowage position requires
unpinning the escape pole at the starboard and port attachments,
rotating the pole so it is flat against the middeck ceiling and
strapping it to the ceiling. An alternate on-orbit stowage approach
also requires unpinning the escape pole at the starboard and port
attachments, rotating it so it is flat against the middeck ceiling
and strapping it to the ceiling.
The side hatch water coolant lines for side hatch thermal conditioning
were modified to accommodate the installation of the side hatch
pyrotechnic separation system.
The flight crew members' seats were also modified to accommodate
the seat/crew altitude protection system suit for each crew member.
The pyrotechnically operated crew compartment depressurization
valve consists of two flapper valves with debris screens on the
crew compartment side and payload bay side that open to depressurize
the crew compartment and close when the pressure equalizes.
It is noted that the hatch jettison features could be used in
a landing emergency.
The crew member's altitude protection suit includes an emergency
oxygen system, pilot and drogue parachutes that are operated automatically
and have manual backup, a main parachute that is operated automatically
and has manual backup, a seawater activation release system, flotation
devices, a life raft and survival equipment. The crew altitude
protection suit and its associated equipment weigh approximately
The side hatch jettison thruster contractor is OEA, Denver, Colo.
The pyrotechnics contractor for the hatch tunnel, hinge and the
energy transfer system lines is Explosive Technology, Fairfield,
Calif. The escape pole is government-furnished equipment that
is supplied by NASA's Johnson Space Center, Houston, Texas, as
is the crew altitude protection suit.