Chapter 1. Escape
and Survival Systems Description
The crew module is composed of many systems such as:
- Seat and restraint.
- Emergency oxygen.
They are interconnected by means of shielded mild detonating
cord (SMDC) which acts as a stimulus transfer medium. The SMDC is provided with time delay
initiators (TDI) and one-way explosive transfers to ensure proper sequencing of the
various functions. Explosive transfer connectors are incorporated in the system for firing
redundancy. After actuation of the initiation system, sequencing of all systems through
landing and flotation is automatic. The escape and survival systems consist of the crew
module system and oxygen systems. The oxygen systems are the normal (liquid) oxygen
system, oxygen quantity and pressure warning system, and emergency (gaseous) oxygen
Now that you have a general idea of what makes up the crew
module ejection system, let's take a closer look at the module system and the oxygen
system. Let's begin with the crew module.
The crew module, (fig. 1 ), provides maximum comfort and protection for both crewmembers
during normal and emergency conditions. It is integrated into the F-111 aircraft
encompassing the pressurized cabin and forward portion of the wing glove. The two crew
seats are positioned side by side and have restraints incorporated that enhance freedom of
movement and comfort by eliminating the need for a personal parachute and survival
equipment to be fitted to the crewmembers. Survival equipment and a recovery parachute are
a part of the crew module system. During an emergency, the crew module is separated from
the aircraft and propelled to a height sufficient for successful recovery throughout the
aircraft performance envelope. The system has features to reduce the landing shock on land
or water and has self-righting buoyancy, flotation capacity, and protects the crewmembers
against environmental hazards.
The three functions of the oxygen systems are normal, quantity and pressure warning, and
emergency. During normal operations, the normal (liquid) oxygen system supplies the
crewmembers with breathing oxygen. When the normal oxygen system malfunctions, low system
pressure and low liquid oxygen quantities are indicated by a normal oxygen quantity and
pressure warning system.
Figure 1. F-111
An emergency (gaseous) oxygen system supplies breathing
oxygen to crewmembers during normal oxygen system failure or during an ejection.
As stated earlier, the crew module escape system is made up
of many systems which work together during an ejection. These systems can be divided into
three categories: pre-ejection, ejection, and post-ejection. The pre-ejection category
consists of the ejection initiators, guillotines, emergency oxygen, mechanical explosive
interrupt, a radio beacon, a 3.0-second TDI, chaff, and a .35-second TDI. Let's take a
closer look at some of the components that may be unfamiliar to you.
The ejection initiators are used to start the sequence to separate and eject the crew
module from a disabled aircraft, much like the ejection initiators used in any other
aircraft. However, as you can see in figure 2, the initiators used in the F-111 are quite
different in looks and operation. Safety pins are normally installed in the ejection
initiator handles to prevent accidental firing of the initiators, whenever aircraft
maintenance is being performed.
An ejection initiator on each side of the center console is
within easy reach of both crewmembers and permits either crewmember to start the crew
module ejection sequence. Each initiator has a D-shaped grip that must be squeezed and
then pulled upward to actuate the built-in firing mechanism. Squeezing the grip releases
the initiator's built-in lock release. As the grip is pulled, the firing mechanism first
compresses the firing pin springs. As the grip reaches its upper limits, the spring
tension drives the firing pins into a percussion-type primer. The primer actuates the
explosive train and the explosive crossover.
Guillotines sever antenna leads, secondary control cables, and an oxygen line. Refer to
the guillotines in figure 3. The cartridge is fired by the SMDC to actuate the guillotine
blade for severance. The secondary controls guillotine is located on the bottom surface of
the crew module floor in the left cheek area of the fuselage, the blade antenna leads
guillotine is located on the centerline of the crew module glove beneath access cover
2410, and the leading edge antenna leads guillotine is located on the centerline of the
crew module glove beneath access cover 2420.
The emergency oxygen system provides both crewmembers with a 10-minute supply of oxygen
during ejection or when the normal aircraft oxygen system fails. During the pre-ejection
sequence, the emergency oxygen system is actuated explosively by the SMDC from the
ejection initiators. If the normal oxygen system fails during flight, the emergency system
can be turned on manually.
Mechanical explosive interrupt
(MEI). The MEI is a unit, that is controlled by the crewmember with a
chaff interrupt lever, that allows or stops the explosive propagation to the emergency
radio beacon and the 3.0-second TDI which, when fired, actuates the chaff dispenser. If
the unit is closed, then propagation is stopped. The TDI and emergency radio beacon are
not activated. If the unit is open, then propagation continues, activating both the
emergency radio beacon and a 3-second TDI. The TDI gives the crew module time to clear the
aircraft before it fires, actuating the chaff dispenser.
The radio beacon sends out radio signals for rescue purposes after an ejection. If the MEI
is in the open position, the beacon will automatically send out its signal. If the MEI is
closed, the radio beacon can be manually operated by a switch in the cockpit.
The .35-second time-delay initiator is fired by the SMDC from the ejection initiators and
delays the actuation of the components that make up the severance system.
Now let's look at the ejection category which consists of
flexible linear-shaped charges (FLSC), two. 15-second time-delay initiators, a rocket
motor, a dual mode, q-actuated selector, a 1.6-second time-delay initiator, a 4.4-second
time delay initiator, a 1.0-second time-delay initiator, a "G" sensor initiator,
and the select/interrupt valve.
Flexible linear-shaped charge.
FLSC severs the module from the aircraft. It is installed around certain covers and splice
plates on the module to cut the metal for severance and is formed in a chevron-shaped
cross section for use in severance strips. Also, it is used to cut a larger hole in the
upper nozzle of the rocket motor during high-speed ejections. A booster tip is installed
on each end. The amount of explosive per foot of FLSC is selected to cut a specified
thickness of metal.
Them are two .15-second time-delay initiators installed in the ejection system. One delays
firing of the stabilization/brake parachute catapult until the module has separated from
the aircraft and the other delays firing of the FLSC in the rocket motor upper nozzle in
mode 1 until the module has cleared the aircraft.
In figure 4, you see that the rocket motor is composed of an upper closure or compartment,
a 9-inch by 58-inch steel cylinder case, and a lower closure or compartment. Starting at
the top of the upper closure, the SMDC propagation actuates the firing pin. This in turn
fires the percussion primer in the igniter cup, which then detonates the motor ignition
pellets. These ignition pellets are suspended in a foam that aids in their detonation. The
rapidly detonating ignition pellets cause the propellant grain in the steel cylinder to be
Figure 4. Rocket
The rocket motor lower nozzle provides 27,000 pounds of
thrust. To avoid excessive "g" forces to the crewmembers, the rocket motor is
provided with two concentric upper nozzles, secondary and auxiliary. The small auxiliary
nozzle in the center of the upper nozzle fires simultaneously with the lower nozzle. This
action provides 500 pounds of thrust to counteract slow-speed crew module pitch up at
speeds below 300 knots. At speeds above 300 knots, after a .15-second delay, the upper
nozzle burst diaphragm is severed by a flexible linear-shaped charge (FLSC) to increase
the exhaust-flow area, thus increasing its thrust. Because of the increase in the
exhaust-flow area, the rocket motor operating pressure is lowered, which results in
reduced thrust of 9,000 pounds at the lower nozzle and increases the upper nozzle thrust
to 7,000 pounds. This overall decreased thrust extends the operating time and reduces
excessive "g" forces.
Dual-mode, q-actuated selector.
In figure 5, you see the dual-mode, q-actuated selector. It continuously senses aircraft
speed and selects the appropriate time delay. The letter "q" is used to identify
forces or pressure required to actuate various pressure-sensitive aircraft devices.
Pressure from the pitot static system, or ram pressure, is sensed at one end of the
q-actuated selector, while dynamic pressure is sensed at the other end. Due to
differential pressure, the q-actuated selector allows activation of a 1-second TDI to the
barostat lock initiator and blocks propagation to the rocket motor upper nozzle when
aircraft speed is less than 300 knots. When aircraft speed is greater than 300 knots,
differential pressure is changed so that the q-actuated selector blocks propagation to the
1-second TDt and allows activation of SMDC to the. 15-second TDI to the rocket motor upper
nozzle to fire.
Dual-mode, q-actuated selector.
Another explosive train, with a 4.4-second time-delay initiator, is provided to back up
both the dual-mode, qactuated selector and the g-sensor initiator. This equipment ensures
that the barostat lock initiator is never activated more than 4.4 seconds after the rocket
motor is fired.
This time delay allows the module to gain altitude during a mode 1 ejection. Upon
actuation, it fires the barostat lock initiator.
The g-sensor initiator (fig. 6) is located in the survival equipment explosive device
compartment. A TDI delays firing the g-sensor initiator for 1.6 seconds after rocket motor
ignition during high-speed ejections. The forward motion of the crew module may be
relatively high immediately after ejection of the crew module at speeds above 300 knots.
After the forward motion decreases to approximately 2.2 (+/- 1 ) g' s, the g-sensor
initiator fires and activates the barostat lock initiator.
Dual-mode, q-actuated selector.
The select/interrupt valve works similarly to the mechanical explosive interrupt. It
either allows or blocks explosive propagation leading to the stabilization/brake parachute
cutters. The direction of propagation depends on the mode of ejection selected by the
dual-mode, q-actuated selector. When a mode 1 is selected, a detonation transfer assembly
(DTA), which is another type of mild detonating cord, repositions the select/interrupt
valve. When the recovery system operates, DTA propagation passes through the repositioned
valve and fires the cutters.
ejection (recovery system)
The post ejection system consists of the barostat lock
initiator, the recovery parachute catapult, the recovery parachute, a 3.0-second TDI, a
7.0-second TDI, the impact attenuation bag, the UHF antenna, the recovery parachute
repositioning release retractor, and the stabilization/brake parachute cutters. Let's
begin our discussion of this category with the barostat lock initiator.
Barostat lock initiator.
The barostat lock initiator (fig. 7) consists of two operating trains. Normally, an
aneroid bellows in each explosive train is locked to prevent firing of the train, constant
cycling, and wear-out. Firing of the SMDC into the barostat inlet port initiates an
explosive charge that retracts the pins which normally lock the bellows. The aneroid
bellows prevents the firing of the explosive train until the module falls to within 14,000
and 16,000 feet. Below this pressure altitude, atmospheric pressure compresses the bellows
sufficiently to release the firing pins that initiate the booster caps and continue the
detonation sequence to remove the recovery parachute and blade antenna severable cover and
fire the recovery parachute catapult. The barostat lock initiator is located on the
explosive component support bracket in the rocket motor compartment.
Barostat lock initiator.
In figure 8, you see the recovery parachute, a 70 foot, flat-diameter, ring sail parachute
equipped with a reefing line cutter. Reefing lines prevent the large parachute from fully
opening until the suspension lines are fully stretched. The parachute is stowed in a
compartment aft of the left crew seat bulkhead.
The recovery parachute is deployed into the airstream by a
recovery parachute catapult. The parachute is assisted in extending by a small pilot
parachute. The recovery parachute is deployed in a reefed or partially inflated condition
to reduce the opening shock of the parachute to the crew module. When the suspension lines
are fully stretched, the reefing line is cut by the reefing line cutter to allow the
parachute to fully blossom. The recovery parachute is then suspended as it appears in the
smaller illustration on the right in figure 8.
Module of FB-111A 68-243 showing less than
optimum landing situation. The pilot of this aircraft suffered minor injuries from
tree branch penetration of the module floor during the assent. (Image via www.FB-111.net )
The 3.0-second time-delay initiator allows for recovery parachute deployment before
activating the nitrogen bottles for the impact attenuation bag.
This time delay allows the recovery parachute to fully blossom before firing the FLSC to
free the UHF antenna. It also fires the recovery parachute repositioning release
Impact attenuation bag.
The impact attenuation bag (fig. 9) is made of neoprene coated nylon cloth and is stored
under the crew compartment. The bag has several interconnected chambers; and when these
chambers are inflated, the bag serves as a cushion and absorbs the landing shock of the
Figure 9. Impact
The bag contains blowout plugs of various sizes. These plugs
are retained by shear pins. Upon landing, the pins shear to release the blowout plugs,
allowing the bag to deflate which reduces shock of crew module impact to within allowable
FLSC severs the UHF antenna cover after 7 seconds. Once the cover has been severed, the
UHF antenna is free to extend and send out radio signals from the radio beacon.
repositioning release retractor. There are three release retractors
provided in the recovery system. These retractors are the recovery parachute repositioning
release retractor, aft release retractor, and forward release retractor. Each retractor
operates the same mechanically. The repositioning release retractor provides a means for
greater recovery loads to be absorbed by the parachute clevis and to release this clevis
for crew module repositioning and parachute bridle deployment. After landing, the forward
and aft release retractors provide a means for releasing the recovery parachute bridle
lines and thus the recovery parachute from the crew module. Upon firing the retractor
cartridge by means of SMDC, gas pressure actuates the retractor pin assembly into the
refractor housing to release the attached components.
cutters. These cutters are fired by a detonation transfer assembly
and release the stabilization/brake parachute during mode 1 ejection.
The stabilization system consists of the stabilization/brake
parachute catapult, the stabilization/brake parachute, stabilization glove, stabilization
flaps, and pitch flaps. Let' s begin our discussion of this system with the
This is a 6-foot diameter hemisphere-type parachute that, by means of bridle lines, is
attached to the crew module at the aft end of the stabilization glove. The parachute is
pressure packed around the outer barrel of the parachute catapult and stored in a
compartment on the top aft end of the stabilization glove.
After the stabilization/brake parachute severable cover is
severed, the parachute catapult is fired. This ejects the parachute and catapult outer
barrel aft and upward from the stabilization glove. As the bridle lines pull tight, the
outer barrel strips the deployment bag from the parachute. This permits the parachute to
deploy, slowing the module down and providing lateral stability. If the ejection takes
place below 300 knots, the stabilization/brake parachute is cut away from the module
concurrent with recovery parachute deployment to prevent possible entanglement of the two
The stabilization glove is an integral part of the crew module and is also the forward
part of the aircraft wing. This glove section serves to stabilizes the flight of the crew
module by preventing pitch down after its separation from the aircraft and until the
recovery parachute is supporting the module. It also houses the aft flotation bags and the
The stabilization flaps are located forward of the forward pressure bulkhead on the lower
surface bulkhead. They are stowed in the retracted position and, when released, extend
approximately 64ø from the forward pressure bulkhead. At high speeds, the flap linkage
stretches under aerodynamic forces so that the flaps rotate to approximately 79ø. The
spring-actuated stabilization flaps, (which are released upon separation of the crew
module from the aircraft), reduce crew module pitch up at transonic speeds following
separation from the aircraft.
The pitch flaps are attached to a hinged metal frame with a compressed spring, on the
lower aft end of the stabilization glove. Upon separation of the crew module from the
aircraft, the compressed spring actuates the pitch flaps to the lowered position. A
synchronizing cable, routed through pulleys on both flaps, assures simultaneous
deployment. The pitch flaps lower the trim angle of the module approximately 10ø to
assist in horizontal stability.
219. System overview
1. How are the crew seats arranged and how have they been
designed for freedom of movement and comfort?
2. What are the three functions of the oxygen system?
3. What is the purpose of the quantity and pressure warning
function of the oxygen system?
1. What is required to be done to the ejection initiators
whenever aircraft maintenance is being performed?
2. Where are the guillotines located?
3. How is the emergency oxygen system actuated?
4. What is the MEI used for in the ejection sequence?
5. What is the radio beacon used for and how is it operated?
1. How is FLSC used throughout the F-111 module system?
2. What is the purpose of the .15-second TDI's installed in
the ejection system?
3. How is the rocket motor designed to avoid excessive
4. What is the purpose of the 4.4-second TDI in the
5. What is the purpose of the select/interrupt valve?
1. What components make up the post ejection system?
2. Where is the barostat lock initiator located?
3. How is the recovery parachute initially deployed?
4. What is the purpose of the repositioning release
223. Stabilization system
1. How and where is the stabilization/brake parachute stored?
2. During ejections below 300 knots, when is the
stabilization/brake parachute cut away from the module and why?
3. What is the purpose of the stabilization glove?
4. Upon separation of the crew module from the aircraft, how
are the pitch flaps actuated?
Chapter 2. Crew
Module Ejection Sequence
As stated earlier, the crew module ejection systems are
interconnected by means of shielded mild detonating cord (SMDC). To ensure proper
sequencing of functions, SMDC uses time-delay initiators and one-way explosive transfers.
Explosive transfer connectors also are incorporated in the systems for firing redundancy.
After ejection begins, the sequence of events is rapid, in fact almost simultaneous. Delay
initiators in the systems, however, do delay firing of certain components until other
parts of the explosive system are fired. Refer to figure 10 as you study this system.
|Figure 10. Crew Module Ejection Sequence.
Figure 11. SMDC.
Crew Module operation.
Ejection is initiated by actuating either of the ejection initiators. The ejection
initiators detonate the SMDC which provides a simultaneous transfer medium for the the
crew module. Each end of the SMDC lines has has a stainless steel booster tip (fig 11).
Propagation from one booster tip to another is accomplished by the impact of the shrapnel
formed by fragmentation of the thin stainless steel booster tip sheathing. The detonation
rate of the SMDC is 20,000 to 25,000 feet per second with an associated pressure front of
3 to 4 million psi.
As SMDC propagation occurs, the following events occur.
- Both powered inertia-lock retraction devices fire to retract
the upper restraint harness restraining the crewmembers.
- The secondary controls guillotine is actuated to sever
secondary control cables and the normal oxygen hose, the blade antenna leads guillotine is
actuated to sever the coaxial antenna leads, and the leading edge antenna leads guillotine
is actuated to sever the leading edge antenna leads in the wing.
- The emergency oxygen system is activated.
- The propagation of SMDC continues to the mechanical explosive
interrupt which allows or stops the propagation as the crewmember desires. If the unit is
closed then propagation is stopped. The chaff dispenser and emergency radio beacon are not
activated. If the unit is open, then propagation continues and activates the emergency
radio beacon and a 3.0 second time-delay initiator. The time-delay initiator gives the
crew module time to clear the aircraft before it fires, actuating the chaff dispenser.
- The 0.35-second time-delay initiator is activated. This
time-delay initiator delays firing of the rocket motor and severance of the crew module
until steps a through e have occurred. Severance. After an interval of 0.35 second, the
time-delay initiator fires, causing the following events:
- The 0.15-second time-delay initiator is activated delaying
firing of the stabilization/brake parachute catapult until after the crew module has left
- The rocket motor is ignited.
- The backup SMDC to the guillotines, emergency oxygen system,
and chaff dispenser is detonated. This portion of the system is provided in the event of
failure of the SMDC when ejection is initiated.
- The FLSC is detonated, severing the crew module mating devices
from the aircraft and the stabilization/brake parachute severable cover from the crew
module. At the same moment the FLSC severs the crew module from the aircraft, the 1.6 and
4.4-second time-delay initiators are activated. At this point, the dual-mode, q-actuated
selector determines which route the SMDC takes. The q-actuated selector senses aircraft
speed and determines whether the aircraft speed is above or below 300 knots so that it can
select the appropriate time delay.
When the module is completely severed from the aircraft, the rocket propels the crew
module up and away from the aircraft. After a 0.15-second delay, the stabilization/brake
parachute catapult is fired and deploys the parachute.
At speeds below 300 knots, the dual-mode, q-actuated selector
prevents propagation to the rocket motor upper nozzle diaphragm FLSC assembly, and
activates a 1.0-second delay initiator and DTA lines going to the select interrupt valve.
At this point, the select interrupt valve is repositioned allowing the stabilization/brake
parachute cutters to release the stabilization/brake parachute during the low-mode
ejection. The 1-second delay allows the crew module to clear the aircraft and stabilize in
flight, before the recovery parachute is deployed. After a 1-second delay, the initiator
will fire and activate the barostat lock initiator. The barostat lock initiator, when
fired, activates the recovery system and releases the stabilization/brake parachute.
At ejection speeds above 300 knots, the dual-mode, q-actuated
selector prevents propagation to the 1.0-second delay initiator and DTA lines leading to
the select/interrupt valve and allows propagation to activate the 0.15-second time delay
initiator. Since the selector interrupt is not repositioned during high-speed ejections,
the stabilization/brake parachute remains attached to the module throughout the ejection
sequence. Firing of the 0.15-second time-delay initiator continues SMDC propagation to the
rocket motor upper nozzle FLSC assembly to sever the diaphragm. Because the barostat lock
initiator cannot be activated through the dual-mode, q-actuated selector above ejection
speeds of 300 knots, a 1.6-second time-delay initiator is provided. This initiator delays
SMDC propagation to the g-sensor initiator for 1.6 seconds after rocket motor ignition.
Once the 1.6-second time delay has elapsed, the initiator activates the g-sensor
initiator. After the forward speed of the crew module slows down to approximately 2.2 g's,
the g-sensor initiator fires, activating the barostat lock initiator.
Another explosive train, with a 4.4-second time-delay
initiator, is provided to back up both the dual-mode, q-actuated selector and the g-sensor
At this point, the module has separated from the aircraft and
is on its descent. Now let's discuss the events that take place during this phase of
ejection. Descent. Upon activation of the barostat lock initiator, the aneroid bellows are
released. The firing pins are retained by the bellows until the crew module falls to
between 16,000 and 14,000 feet. When the firing pins are released, detonation occurs.
Propagation continues to the recovery parachute cover FLSC, DTA leading to the select
interrupt valve, and the recovery parachute catapult. The parachute cover FLSC and
recovery parachute catapult are fired simultaneously, causing the catapult to deploy the
recovery parachute. The DTA line coming off the cover going to the select interrupt valve
is activated also. However, depending on whether the select interrupt valve was previously
repositioned by the q-actuated selector determines whether the stabilization/brake
parachute is released from the module. At this point, the crew module is fastened to the
recovery parachute by the repositioning release retractor. At the same time the recovery
parachute catapult is fired, the 3- and 7-second time-delay initiators are activated. The
3-second time delay allows the recovery parachute to blossom before actuating the impact
attenuation bag system. After the 3-second TDI is fired, propagation is continued to sever
the attenuation bag cover with the FLSC and fire the pressure source explosive valve. This
releases compressed gas to inflate the attenuation bag. If automatic recovery parachute
deployment fails, the recovery parachute deploy initiator is provided.
After a delay of 7 seconds, the parachute repositioning
release retractor is activated to release the recovery parachute clevis. As the parachute
pulls away from the module, it deploys the forward and aft bridle lines. The bridle lines
that connect the recovery parachute to the crew module forward and aft release retractors,
permit the crew module to assume a level landing position. At the same time the
repositioning release retractor fires, the emergency UHF antenna actuator is fired to
extend the antenna.
You see in figure 12 that just before landing, the severance
and flotation initiator handle is actuated to provide inflation of the self-righting and
aft flotation bags (detail A shows the aft flotation bags, and detail B shows the
self-righting bags). Detonation shock waves from the severance and flotation initiator are
propagated through the SMDC to fire the aft flotation and left self-righting bag pressure
source, a 75-second time-delay initiator, and FLSC which severs the self-righting and aft
flotation bag covers from the crew module. The pressure source explosive valve is
simultaneously activated to release compressed gas to both aft flotation bags and the left
self-righting bag. The 75-second time delay is provided to allow the crew module to settle
on land, or if a water landing is made, to allow it to surface.
Self-Righting and Aft Flotation Bags.
After firing of the 75-second time delay initiator, the right side self-righting bag
pressure source valve is activated This action releases compressed gas to inflate the bag.
If the crew module is inverted, it is pushed to an upright position as the bag inflates
Upon landing on the ground or water, the landing shock is
absorbed by controlled deflation (blowout plugs expelled) of the impact attenuation bag
Immediately upon landing, the recovery parachute release initiator handle is actuated
Propagation through the SMDC actuates the release retractors
and releases the recovery parachute from the crew module. This prevents dragging of the
crew module along the ground by high winds, or if a water landing was made, from being
pulled under the surface.
If, after a water landing, additional buoyancy is required to
keep the crew module afloat, the auxiliary flotation bag is deployed. This is accomplished
by pulling the auxiliary flotation handle. Propagation through the SMDC simultaneously
fires the FLSC to cut the severable cover and actuates the pressure source explosive
valve. This releases compressed gas to inflate the bag.
If the aircraft is ditched in water and the crew module is
still attached to it, it can be released by actuating the severance and flotation
initiator handle. Propagation through the SMDC will sever the module from the aircraft and
activate the emergency oxygen system, aft flotation system, and self-righting system. At
this time, the crew module is resting in an upright position, and it provides the
crewmembers with shelter until they are rescued.
224. Ejection sequence
1. How is SMDC propagation transferred from one line to
2. List the events that occur when the ejection control
initiators are fired.
3. Upon detonation of the FLSC, during the severance phase,
what components are severed?
4. What is the purpose of the 1.0-second time delay initiated
by the dual-mode, q-actuated selector?
5. What is the purpose of the 4.4-second time-delay