Safety is a major concern in the aircraft industry both in commercial and military services. In the fighter jets, there are several unique mechanisms used other than the commercial airliner. Pilots in the fighter jects can abandon the ship in case of an emergency but the other types of aircraft cannot use that kind of mechanism because the passengers are boarded.

1. Aircraft Safety Systems
Emergency Evacuation Systems of
Military Aircraft

2. 1
1 Abstract
Safety is a major concern in the aircraft industry both in commercial and military services. In the
fighter jets, there are several unique mechanisms used other than the commercial airliner. Pilots in the
fighter jects can abandon the ship in case of an emergency but the other types of aircraft cannot use that
kind of mechanism because the passengers are boarded.
In this report, the equipment uses in the military aircraft to eject and evacuation are mentioned
briefly. The history of the aircraft ejection system, the development throughout the time, the modern
evacuation systems, procedures, regulations, and several other details are included in different sections.
Human anthropometry is the key factor when designing safety equipment because of the range of
height, weight, and size of the body. Because of that, there are several ranges for the height, weight,
and size of the body for the fighter jet pilots. These factors are mentioned briefly in this report.
The references were given at the end to get more ideas about those systems and subsystems.

3. 2
2 Table of Contents
1 Abstract............................................................................................................................................. 0
2 Table of Contents.............................................................................................................................. 2
3 Introduction....................................................................................................................................... 3
4 Investigations of Accidents and Incidents ........................................................................................ 4
5 Regulations ....................................................................................................................................... 4
6 Equipment......................................................................................................................................... 5
6.1 Parachutes.................................................................................................................................. 5
6.2 Light Ejection Escape Equipment ............................................................................................. 9
6.2.1 External escape system....................................................................................................... 9
6.2.2 Canopy removal system ..................................................................................................... 9
6.2.3 Seat ejection system ......................................................................................................... 10
7 References....................................................................................................................................... 16

4. 3
3 Introduction
Military aviation safety is a major topic in both fighter and crew transport aircraft fleets in any
military sector. That also consists of multi-disciplinary fields, and safety is also involved with several
other areas such as electronic, electrical, propulsion, NDT, etc. Safety is more critical because that costs
money and, most importantly, the lives of the people, both military and civilians.
In history, the safety factors and procedures are limited because the flying altitudes are low
compared to the current aircraft abilities, and speeds are within the subsonic region. But with the advent
of the complex systems and higher maneuverability with higher technologies the capabilities are
widened. So that safety concerns become more critical.
In the very beginning, the aviators and other crew have parachutes as the primary method to abandon
the ship in when it is in the flight envelope. That method is used in modern-day also, but the techniques
and technologies have improved significantly. The technique of ejecting gets more complicated when
the aircraft is flying in supersonic speed, and altitude is more than 14,000 feet. So, there are several
safety protocols to eject himself or with the other members. The ejection procedures are different in
rotorcrafts, and there are several safety precautions to get rid of the harmful effects from the rotor, in
some rotorcrafts.
Apart from abandoning the ship, there are other several safety equipments in several aircraft to land
the breakdown aircraft safely with a hard landing. After that, the investigations are carried out to find
the reasons for that incident or accident and categorized that based on the severity.
Those accident and incident rates are reduced with time, and now the military standards are at a
higher level. But those standards are different from the civil standards and treat as different.

5. 4
4 Investigations of Accidents and Incidents
Several authorities have the power to investigate accidents and incidents relevant to military
standards. The secretary of defense and similar military services have the authority to investigate any
accident or event happen. Both legal and safety investigations are done by the National Transport Safety
Board (NTSB) and the relevant Civil Aviation Authority (CAA). Generally, the department of defense
(DoD) in the United States of America creates policies about military standards to safeguard aviation
safety [1]. Colour
DoD categorized accidents in three different categories as follows.
1. Aircraft flight accident – there is intent for flight, and damage to the aircraft
2. Aircraft flight-related accident – there is intent for flight, and no reportable damage to the
aircraft but the accident involves a fatality, reportable injury, or reportable property damage
3. Aircraft ground operation accident – there is no intent for flight and which results in damage
to an aircraft, death or injury.
According to the CRS report for congress, the USA in 2003, 3072 people died in military accidents
between 1980 and 2003 [1]. But with the investigations and their recommendations, the rate was
reduced drastically, which satisfies the objective of the investigations.
According to the CRS report, fixed-wing aircraft has fewer mishap rates because the
maneuverability is difficult. Another thing is combat aircraft have less mishap rates than other non-
combat aircraft [1]. Human errors have caused in most of the accidents and incidents. Mechanical
failures and material failures are there but in minimum rate.
5 Regulations
CCAR 23 – certification basis of acrobatic aircraft [2].
CCAR 23.561 – general aviation seat
CCAR 23.562 – Emergency landing dynamic conditions
CCAR 23.807 – Emergency exits
CCAR 23.785 – Seats, berths, litters, safety belts, shoulder harnesses
AC 23-19A – FAA policy explanation about ejection seat certification [2].
AC 23-19A 23.562 – certification of the ejection seat
MIL-A-S-18471G – Military standards of US NAVY for ejection seat - System, Aircrew automated
escape, Ejection seat type, and general specification [2].
GJB 1800A-2007 – Military standard of China air force for ejection seat - General specification for
ejection seat type of aircrew emergency escape system [2].

6. 5
6 Equipment
Special equipment is used in military aviation in case of the safety of the aircraft and the crew.
6.1 Parachutes
The evolution of the modern parachute was started by Everard Calthrop, who was an engineer after
seeing a tragic accident of the Wright biplane. From that accident, his friend Charles Rolls was dead as
the first Englishman who died in a flying accident in 1910. He developed a parachute ‘Guardian Angel’
and tested in different formats.
The requirements of the parachutes were critical and came into action after several considerations
and discussions. Finally, common standards were issued, and several safety procedures were released
to action.
The restrictions of airmen to leave from the aircraft were lifted and airmen can leave form the aircraft
without considering the position of the aircraft and airmen should wear parachute all the time of the
flight. The operating procedures should not depend on the situation and condition. The size, weight and
comfort to the airmen rely on the type of parachuteare but that should be consists of simple
constructions and easily packable conditions.
Figure 1 - Preparing to test, on the left, the Calthrop
'Guardian Angel' and, attached to the basket in its
conical container [11].
Figure 2 - Practical
parachute training in
1903s [11].

7. 6
There are several types of parachutes used in the field and commonly used as seat type, chest type,
back type, and headrest type. In fighter jets, commonly used seat type parachute, other pilots use back
type parachute and troops use chest type parachute [3], [4], [5].
Figure 3 - Components of harness-container assembly
Figure 4 - Modern parachute container system
Figure 5 - SE-5L Parachute Specification

8. 7
The design of the parachute deployment is related with the anthropometry because some shocks and
vibrations happen during free-fall, deployment of the parachute and landings.
Before wearing a parachute, that should be thoroughly checked. All pins should be properly sealed
in a closed loop. Rip chord handle should secure in the pocket and no damage signs should be there. Al
the harnesses and locks should be checked. Especially, the date of the packing of parachute should be
checked as there are a re-packing interval and lifetime for the parachute.
There are two parachutes in one container, one is the main canopy and the other one is reserve chute.
If the main canopy is not deployed the reserve should be operated. The ripcord is positioned to pull by
the right hand and there are provisions to pull is by the other hand or using both hands. The ripcord
should be operated after clearing the aircraft and maintain the proper distance from the other divers.
The full deployment of the parachute takes a maximum of 3 seconds. The diver should operate the
parachute with the altitude. If the altitude is below 3000 ft, the ripcord should pull immediately. If the
altitude is between 3000 – 10 000 ft, ripcord should pull after 5 seconds and above 10 000 ft, the diver
should wait until the altitude gets low.
The operator must careful about the aircraft as the parachute can be entangled with the aircraft in
some cases. Most probably that kind of incident will end up with fatal accidents.
Figure 6 - Parachute Deployment Sequence

9. 8
Several researches were conducted to analyze the neck loading of the operator during free fall in
skydivers and the same results can relate to the human escape system [6]. Also, the limitation of the
experience of the operating parachute is another reason for several fatal injuries [7]. Parachute operators
came to the ground from very high altitudes in a very short period and the human body is traumatized
due to forces and pressure difference in that period. So, parachute opening shock (POS) is the reason
for most of the cases [8]. The speed of the body depends on the position of the body. But the diver
came into terminal velocity (20 km/h) within a couple of seconds and deceleration is called the POS.
That creates a force that bends all operators’ vertebra and neck towards his back and creates
hyperextension. So, the stability of the muscles and the spinal cord is lost in the neck region. That will
create trauma and injuries at thoracic, lumbar and cervical vertebra [8].
The hardest part is the safe landing. All the divers should face into the wind to reduce the ground
speed and lock their legs together from thighs to ankles. The Knees should bend, and toes should point
downwards at the last phase. The Parachute Landing Fall (PLF) should perform in order of touching
the balls of the feet, side of the calf, side of the thigh, side of the buttock and side of the back to reduce
the impact [9].
The aviators should undergo a proper parachute operating training in case of an emergency.
Otherwise they will end up with severe injuries even after saving their lives from aircraft accident but
during the operating of the parachutes,
Figure 7 - Parachutist
entangled with in the
aircraft - Florida, 2014

10. 9
6.2 Light Ejection Escape Equipment
The light ejection equipment set has several subsystems that work-integrated together. Some of the
subsystems are initiation subsystem, propulsion subsystem, canopy release or break subsystem,
parachute subsystem, interseat sequencing subsystem.
There should be higher reliability for the propulsion subsystem, canopy release subsystem,
parachute subsystem because there is no pre-testing facility until that operates. Those systems should
be available in a whole flight envelope because the time of emergency cannot be predicted before. The
pilot should have to be able to eject anytime between take-off and landing.
The process of designing and validation of the safety equipment must meet the required standards.
All the equipment should have a simple initiation method with fire protection. There should be enough
protection for members in the flight to minimize injury in the ejection path and the validation should
be given by laboratory testing [2].
6.2.1 External escape system
An external escape system was developed to stop the collision between the ejected pilot with the fin.
Martin Baker designed that system and placed it at the base of the leading edge of the fin. The parachute
was locked down with a simple latch. This system was well designed and could be fitted with minimal
tools in the field [6]. He tested his swinging arm design in the wind tunnel to validate the ejection
system. This system does not contain any explosives and has a simple design.
6.2.2 Canopy removal system
The removal of the canopy of an aircraft near before to the facture or jettison is advisable to avoid
the elevated levels of head, and neck load on the ejection people and those loads will cause to severe
neck damages. If the choice is to go through the canopy, the grass materials should be broken and that
will also increase the head and neck load making the higher potential for aircrew injury
Mainly there are two methods used as jettison and canopy fracturing [7]. Jettison is used by severing
or unlocking the mechanism securing the canopy or hatch to the aircraft’s structure. After that, rocket
Figure 8 - Wind tunnel model of
Martin-Baker's original concept of
a 'swing arm' escape system.

11. 10
motors or thrusters are used to throw away the canopy of the plane by making a clear path, an obstacle-
free path for the ejection seat.
In the method of canopy fracturing, canopy material fractured to open the clear escape path during
seat ejection. When canopies are made with acrylic/ polycarbonate laminates, this method is widely
used.
The interconnected explosive transfer lines in the specific order of firing events used for the escape
system. Apart from that, time delay initiators, one-way initiators, mechanical pull initiators, seat mode
selectors, actuators, pin pullers, and gas generators can be incorporated into the system to execute a
safety canopy.
There are unique advantages and disadvantages of those two methods. The mission, configuration,
flight parameters, and so many other factors will determine which method is most suitable for such
situations. One fact is that canopy fracturing is a faster sequence time with no delay waiting for the
canopy to jettison. Firing hot gas initiator and mechanical pull initiator starts the canopy fracturing
sequence. In jettison, canopy assembly was separated from the aircraft assembly as one piece and seat
ejection won’t occur until a defined delay expires. That delay is used to assure that the assembly is clear
of the aircraft [7].
6.2.3 Seat ejection system
The final step or choice that a pilot must do is the ejection while operation not because they’re
abandoning the ship [8]. In newer two-seat jets, the ejection seats are synchronized so that both ejection
process can be activated using one trigger. But early aircraft like T-38, each person needs to activate
his/her ejection process. In that case, the rear cockpit pilot must be ejected first; otherwise, rockets of
the pilot will burn the person behind.
The activation of the parachute will deploy automatically when the altitude is lower than 14,000
feet. If the altitude is higher than that, the pilot will freeze or go hypoxic. Also, canopy opening in high
altitude is more dangerous because of the thinner air region in the space and will cause injury during
parachute deployment.
The chute can be operated manually if there is an error in automatic chute deployment. In fighter
aircraft, there are emergency oxygen bottles to aid pilots if the chute was deployed over 14,000 feet.
The prediction of the altitude is hard after ejection and when to operate chute manually. So that there
are several instructions given to the pilot. The lower altitude is measured as ‘if the ground coming up
big and fast, pull the ripcord.’
Before ejection, the pilot should have an idea about the ejection situation. If the low altitude ejection
happens, several procedures to follow to minimize the injuries. If the ejection altitude is about 10,000
feet, the pilot has a checklist as a canopy, visor, mask, seat kit, LPU (life preserve unit), 4-line jettison,
steer into the wind, prepare for PLF (parachute landing fall).

12. 11
There was a concept of a unique mechanism for V bomber for the ejection as three crew members
to eject. When the ejection procedure started, crew members tightened to the position and central hatch
was blown off. Then the central seat was ejected, and other crew members could eject in slideways.
This method was successfully tested using test rigs in the early 1960s [6]. According to the statistics,
with the inventions and innovations of Martin-Baker, there are 791 crew members saved their lives.
‘
Several factors need to be considered before selecting the type of ejection seat category for an
aircraft [9]. Figure 10 shows what the factors need to consider when selecting an ejection seat.
In the early stages, ejection seats should be operated manually (MK1). The reason is several pilots
get unconsciousness after ejection, due to higher stress, time limitations to carry out the manual
operation when the ejection was carried out in low altitudes. So that fatality rate is somewhat higher
and manufactures did several experiments to develop full autonomous ejection seats and then gradually
developed MK2 seat. Those fully automatic ejection seats contain personal parachute, drogue chute,
and dinghy pack. After that MK3 ejection seat was designed with the ability to eject at very low
altitudes and very high speeds. There was a requirement for lightweight
After several decades, the zero/ zero ejection process was introduced with the rocket packs in MK6
seats. Zero/zero ejection is the capability to eject in zero altitudes and zero velocity.
The aim of the designing companies is to increase the range of the mass of pilots. To do that, the
size range should be increased but there are system restraint system modifications. The cockpit
arrangement should be changed according to the size of the pilot. If the pilot size is small, the over nose
vision, arms reach and leg reach are limited. In larger size pilot, head clearance and shin clearance are
problematic during ejection as well as operation. The designs are varied with the anthropometry of the
pilot as there are hard as well as soft limitations. With the variation of the height and arm reach, there
is a limited region that should be considered when designing the ejection seat.
Figure 9 - The test rig build to
demonstrate the feasibility if
installing three rearward facing
seats in a V-bomber [6]

13. 12
Because of that, there are several anthropometry modifications using tilting seats, translating
backrest, role fit backrest, role fit spacer and considering the change of center of gravity. The restrained
system is developed with suspension systems and it helps to improve the anthropometry range.
Figure 10 - Factors need to be considered to select ejection seat [9].
Figure 11 - Ejection seat testing setup

14. 13
Figure 12 - Variation of arm reach and leg reach in ejection seat

15. 14
Figure 13 - Leg reach and arm reach of the ejection seat
Figure 14 - Head clearance and Shin clearance in ejection seat
Figure 15 - Over the nose vision plot

16. 15
Figure 16 - Ejecting sequences
Figure 17 - Ejection seat operation sequences

17. 16
7 References
[1] C. R. f. Congress, “Military Aviation Safety,” Specialist in National Defence, Foreign Affairs,
Defence, and Trade Division, 2003.
[2] B. GU, “Airworthiness Certification of Light Ejection Escape Equipment,” The 2nd International
Symposium on Aircraft Airworthiness, pp. 354-357, 2011.
[3] “Airborne Troop Parachute,” MILLS Manufacturing, [Online]. Available:
https://www.millsmanufacturing.com/airborne-troop-parachutes/. [Accessed 7 December 2019].
[4] “Emergency Parachutes,” SPEKON, [Online]. Available:
https://www.spekon.de/en/products/emergency-parachutes/emergency-parachutes.html.
[Accessed 7 December 2019].
[5] “Military Parachute Systems,” Ballenger International, LLC, [Online]. Available:
http://www.ballenger-intl.com/military-parachute-systems.html. [Accessed 7 December 2019].
[6] B. Miller, “AIRCREW SAFETY – MARTIN-BAKER AND THE RAF,” ROYAL AIRFORCE
HISTORICAL SOCIETY, vol. 37, pp. 95-113, 2006.
[7] “Emergency Escape System,” Pacific Scientific Energetic Materials Company, [Online].
Available: https://psemc.com/solutions/military-aircraft-ejection/. [Accessed 01 October 2019].
[8] J. Bennett, “Everything you need to know about ejecting from a fighter jet,” Popular Mechanics,
25 April 2017. [Online]. Available:
https://www.popularmechanics.com/military/aviation/a26193/how-pilots-eject-from-fighter-jet/.
[Accessed 25 September 2017].
[9] “NEW SEAT INSTALLATIONS & RETROFITS,” Martin-Baker Aircraft Co, Ltd, 2019.
[Online]. Available: http://martin-baker.com/products/new-seat-installations-retrofits/. [Accessed
08 September 2019].
[10] “Ejection seats - Products,” Martin-Baker, 2019. [Online]. Available: http://martin-
baker.com/products/. [Accessed 08 October 2019].
[11] A. A. Johnson, “The Evolution of Parachute for Aircrew,” ROYAL AIRFORCE HISTORICAL
SOCIETY, vol. 37, 2006.