One of the requirements to consider in designing an Operational Feasibility

1. DESIGN FOR USABILITY
(HUMAN FACTORS)

2. HUMAN FACTORS/ USABILITY
Understanding and optimizing how
people use and interact with technology is
the subject of Human Factors Engineering
(HFE).

3. HUMAN
FACTORS
REQUIREMENTS

4. HIERARCHY OF HUMAN ACTIVITY
•JOB OPERATION. May involve one or more related
groups of duties, and may require one or more individuals in
its accomplishment.
•Operate a Motor Vehicle
•DUTY. Set of related tasks within a given job operation.
•Driving the motor vehicle
•Registering the motor vehicle

5. •TASK. Constitutes a composite of related activities
performed by an individual in accomplishing a prescribed
amount of work in a specified environment.
•Shifting gears as necessary in order to maintain engine rpm.
•Turning the steering wheel as required to enable the motor
vehicle to move the desired direction.
•SUBTASK. Depending on the complexity of situation, a
task may be broken down into subtasks to cover discrete
actions of a limited nature.
•A machine Adjustment

6. •TASK ELEMENT. May be categorized as to the smallest
logically definable facet of activity (based on perceptions,
decisions, and control actions) that requires individual
behavioural responses in completing a task or a subtask.
•The interpretation of a go/no-go signal

7. PERSONNEL FACTORS
May be categorized in terms of:
•Anthropometric Factors
•Human Sensory Factors
•Physiological Factors
•Psychological Factors

8. Anthropometric Factors
-Physical dimensions of the human body
•Static Measurements – pertain to the human
subject rigid standardized position.
•Dynamic Measurements – are made with the
human in various positions and undergoing
continuous movement. As movement occurs,
body measurements will change.

9. Two basic sources of data to consider:
1. Anthropometric Surveys – in which measurements of a
sample of the population have been made;
2. Experimental Data – derived from simulating the operating
conditions peculiar to the system being developed.

10. Human Sensory Factors
•Vision or Sight
The designers
should consider the
specified degrees of
eye and head rotation
as the maximum
allowable values in
the design of the
operator consoles
and control panels.

12. •Hearing or Noise
The designer needs to address
both the requirements for oral
communication and the aspects for
noise.
 120 dB, a human being will
usually experience a physical
sensation
 130 dB, pain can occur
 Range 50-80 dB, desired
intensity level

13. Physiological Factors
Stress – any aspect of external activity or the environment acting
on the individual(who is performing a system tasks) in such a
manner as to cause a degrading effect.
Some causes of stress are the ff:
•Temperature Extremes
•Humidity
•Vibration
•Noise
•Other Factors (Radiation, Effects of Gas or Toxic substances in the
Air, Effects of Dust & etc.)

14. Psychological Factors
It pertains to the human mind and the aggregate
emotions, traits and behaviour patterns as they relate to
job performance.
•Motivation,
•Dependability,
•Self Confidence,
•Communication Skills, so on,

15. Human Factors Analysis Methods
•Operator Task Analysis (OTA)
•Operational Sequence Diagram (OSD)
•Error Analysis
•Safety/ Hazard Analysis
•Mockups

16. Operator Task Analysis (OTA)
This facet of analysis involves a systematic study of the human
behaviour characteristics associated with the completion of system tasks.
Example:
Function
(1)
Operate Aircraft Power Plant and System Controls
Task (2) Control Jet Engine Operation
Subtask
(3)
Action
Stimulus
(4)
Required
Action
(5)
Feedback
(6)
Task
Clarification
(7)
Potential
Errors
(8)
Time (9) Work
station
(10)
Skill
Level
(11)
Allowable
(9a)
Necessary
(9b)
3.1 Adjust
engine rpm
4.1 Engine
rpm on
tachometer
5.1 Depress
throttle
control
downward
6.1 Increase
in indicated
tachometer
rpm
7.1 Operator
task; Aircraft
Commander
8.1
A. Misread
tachometer
B. Fail to
Adjust
throttle to
proper rpm
9a.1
10 Sec
9b.1
7 sec
10.1
Aircraft
Comma
nder
Seat
11.1
Low

17. Operational Sequence Diagram (OSD)
Used to aid in evaluating the flow of
information from the point when the operator first
becomes involved with the system to the
completion of the mission.

18. Notes on Operational Sequence
Diagram:
Symbols
= Decision
= Operation
= Transmission/Transportation
= Receipt
= Delay
= Inspect/Monitor
= Store
Links
M =Mechanical/Manual
E = Electrical
V = Visual
S = Sound

19. Error Analysis
An error occurs when a human action exceeds some limit of
acceptability, where the limits of acceptable performance have been
defined. Errors may be broken down into errors of omission when a
human fails to perform a necessary task and errors of commission when a
task is performed incorrectly.
The possible causes of error are due to the following:
1. Inadequate work space and work layout
2. Inadequate design of facilities,
equipment and control panels for human factors
3. Poor environmental conditions
4. Inadequate training, job aids and procedures
5. Poor supervision

20. Safety/ Hazard Analysis
The safety/hazard analysis serves as an aid in initially
establishing design criteria and as an evaluation tool for
the subsequent assessment of design for safety.

21. Hazard Classification:
•Negligible Hazard (Category I). Such conditions as
environment, personnel error, characteristics in design, errors
in procedures, or equipment failures that will not result in
significant personal injury or equipment damage.
•Marginal Hazard (Category II). Such conditions as
environment, personnel error, characteristics in design, errors
in procedures, or equipment failures that can be controlled
without personnel injury or major system damage.

22. •Critical Hazard (Category III). Such conditions as
environment, personnel error, characteristics in design, errors
in procedures, or equipment failures that will cause
personnel injury or major system damage, or that will
require immediate corrective action for personnel or
system survival.
•Catastrophic Hazard (Category IV). Such conditions as
environment, personnel error, characteristics in design, errors
in procedures, or equipment failures that will cause death or
severe injury, or complete system loss.

23. Mockups
•Is a model or replica of a machine or structure, used for
instructional or experimental purposes.
•Mockups can be easily constructed with cardboard, wood sheet
metal, actual system components or various combinations of
such.
•The use of mockups can either facilitate the modeling of a
system configuring using CAD methods.

24. Personnel and Training Requirements
Personnel Requirements may be categorized in terms of:
•Operator Personnel
Operations personnel are required to be familiar with the site
emergency plan, and to be familiar in details with the relevant part of
the plan that is related to their processes
•Maintenance Personnel
Maintenance and testing personnel should understand that data
collection after component inspection and testing is important. also,
routine information such as test results or monitoring data

25. Skill Level Classifications are defined as follows:
•Basic Skill Level.
Close Supervision of this individual is normally required.
•Intermediate Skill Level.
This individual requires little supervision.
•High Skill Level.
This individual is qualified to accomplish (or supervise)
all on-site preventive maintenance requirements for the
system.

26. • Thank you