Requirements Document

Operational and Supportability Implementation System Workstation Replacement

 

Focal Point

Charles Young

ARR-100

TEL: (202)-366-4381

FAX: (202)-493-0745

 

Federal Aviation Administration

800 Independence Avenue SW

Washington, DC 20591

 

Table of Contents

1.0 BACKGROUND

2.0 OPERATIONAL CONCEPT

2.1 Operations

2.2 Maintenance

2.3 Quantities and Location

2.4 Schedule Constraints

3.0 TECHNICAL PERFORMANCE

3.1 Operational and Functional Requirements

3.2 Product Characteristics and Performance Requirements

4.0 PHYSICAL INTEGRATION

4.1 Real Estate - N/A

4.2 Space

4.3 Environmental - N/A.

4.4 Energy Conservation - N/A

4.5 Heating, Ventilation, Air Conditioning

4.6 Grounding, Bonding, Shielding, and Lightning Protection

4.7 Cables

4.8 Hazardous Materials

4.9 Power Systems and Commercial Power - N/A

4.10 Telecommunications - N/A

4.11 Special Considerations

5.0 FUNCTIONAL INTEGRATION

5.1 Integration With Other NAS (and Non-NAS) Elements

5.2 Software Integration - N/A

5.3 Spectrum Management - N/A

5.4 Standardization - N/A

6.0 HUMAN INTEGRATION

6.1 Human/Product Interface

6.2 Employee Safety and Health

6.3 Specialized Skills and Capabilities -N/A

7.0 SECURITY

7.1 Physical Security - N/A

7.2 NAS Information Security - N/A.

7.3 Personnel Security - N/A

8.0 IN-SERVICE SUPPORT

8.1 Staffing - N/A

8.2 Supply Support

8.3 Support Equipment

8.4 Technical Data

8.5 Training and Training Support

8.6 First and Second Level Repair

8.7 Packaging, Handling, Storage, and Transportation

8.8 Disposal

9.0 TEST AND EVALUATION

9.1 Critical Operational Issues

9.2 Test and Evaluation.

10.0 IMPLEMENTATION AND TRANSITION

11.0 QUALITY ASSURANCE

12.0 CONFIGURATION MANAGEMENT

12.1 Software Configuration Management - N/A

12.2 Hardware Configuration Management

12.3 Facility Configuration Management - N/A

12.4 Documentation Configuration Management

13.0 IN-SERVICE MANAGEMENT

Appendix A Human Factors Design Guidelines

Flight Service Specialists provide flight planning and weather briefing services to general aviation pilots. The Specialists provide these services at 61 Automated Flight Service Stations (AFSS) throughout the contiguous United States, Alaska, Hawaii and Puerto Rico. The Specialist performs the flight planning and weather briefing functions from five major functional positions within the AFSS. These five positions are of different configurations that are comprised of one or more computer systems, pa variety of data entry devices, display and peripheral devices, software/firmware, communications equipment, and reference documents. The equipment is installed in a workstation. Some of the equipment is "bracket-mounted" and some is "panel mounted". The existing workstations and the layout and positioning of the equipment within the workstations do not meet human factors requirements.

2.1 Operations

Flight Service Position Descriptions: The flight service functions provided by Flight Service Specialists to general aviation pilots can be grouped into five functional positions. Each functional position has unique equipment configurations due to the functional requirements of that position. The five functional positions are as follows:

PREFLIGHT The specialist operates this position to provide essential preflight (weather and flight planning) information to pilots. The specialist interfaces with the flying public via a telephone communication system to deliver preflight information.

FLIGHT DATA The specialist operates this position to transmit flight plans, Notice(s) to Airman (NOTAMs), weather observations and coordinates arrival and departure information to destination airports.

FLIGHT WATCH The specialist operates this position to provide essential weather and aeronautical information for airborne aircraft. The specialist uses air-to-ground communications and weather radar equipment to provide this service to the flying public.

INFLIGHT The specialist operates this position to provide weather and aeronautical information for airborne aircraft. The specialist uses telephone and air-to-ground communication equipment to provide this service to the flying public.

SUPERVISORY This is a management position which is used to perform essential duties for facility operation. The supervisor sometimes uses this position to perform the duties of a Flight Service Specialist

This document establishes the human factors, physical dimensions and flight service equipment configuration requirements for the flight service workstations.

Specifically this document describes:

The human factors requirements for the overall workstation design.

The human factors requirements for the positioning and layout of the flight service equipment within the workstations.

The physical dimensions and equipment configuration requirements for the functional positions.

2.2 Maintenance

The workstation service life is 10 years. It is intended that the workstations will be continue to be used within the AFSSs unless the design becomes obsolete due to as yet undefined future flight service equipment replacements. Generally, equipment of this nature does not require any periodic or corrective maintenance other than routine housekeeping.

2.2.1 Periodic Maintenance

The workstations shall require no periodic maintenance other than general housekeeping requirements of FAA Order 6000.15.

2.2.2 Corrective Maintenance

Workstation corrective maintenance shall be limited to that which can be performed on-site by Airway Facilities personnel.

2.3 Quantities and Location

Approximately 1500 workstations will be required to replace the existing Model 1 Full Capacity (M1FC) workstations at the 61 AFSSs, the William J. Hughes Technical Center, and the Mike Monroney Aeronautical Center. A chair which meets the requirements of Appendix A, section 9.4 shall be procured for each workstation.

2.4 Schedule Constraints

As directed by ADA-1 on May 15, 1998, the workstations must be installed to support the deployment of the Operational and Supportability Implementation System (OASIS) at the second OASIS operational site. According to the OASIS implementation schedule this will occur in March 1999. Remaining workstations will be installed at the AFSSs in time to support OASIS deployment at those sites. The OASIS implementation schedule reflects installation at 3 AFSSs per month through December 2000.

3.1 Operational and Functional Requirements

3.1.1 Workstations shall provide adequate clearance to allow full range of motion for the OASIS video display terminal (VDT) when mounted on the OASIS-provided swivel base.

3.1.2 Workstation task lighting shall be operator adjustable in intensity and orientation.

3.1.3 Operators’ chairs shall be adjustable in seat height, arm rest height, chair back angle.

3.1.4 Workstations shall provide for operator adjustment of OASIS keyboard position, height, and tilt.

3.1.5 The workstations shall require no periodic maintenance other than general housekeeping requirements of FAA Order 6000.15.

3.1.6 The workstation corrective maintenance shall be limited to that which can be performed on-site by Airway Facilities personnel.

3.2 Product Characteristics and Performance Requirements

3.2.1 AFSS OASIS workstations shall provide reading/writing work surface that allows the specialist to review an open, 3" binder containing 8�" x 11" loose leaf pages, while writing on an 8�" x 11" writing tablet.

3.2.2 Preflight and Inflight workstations shall provide bookshelves adequate for storage of 6 - 3" binders containing 8�" x 11" loose leaf pages.

3.2.3 Supervisory workstations shall provide bookshelves adequate for storage of 8 - 3" binders containing 8�" x 11" loose leaf pages.

3.2.4 Workstations shall use non-reflective surfaces to reduce glare and reflections.

3.2.5 Workstations shall use a layout designed to reduce distractions and noise between adjacent positions as well as shorten reaching distances for the operator.

3.2.6 Workstation surfaces shall provide for the elimination of routine electrostatic discharge.

4.1 Real Estate - N/A

4.2 Space

Physical Dimensions:

Preflight workstations shall not exceed 74"H x 50"W x 44"D

Flight Data workstations shall not exceed 74"H x 50"W x 44"D

Flight Watch workstations shall not exceed 74"H x 50"W x 44"D

Inflight workstations shall not exceed 74"H x 100"W x 44"D\

Supervisory workstations shall not exceed 74"H x 100"W x 44"D

4.3 Environmental - N/A.

4.4 Energy Conservation - N/A

4.5 Heating, Ventilation, Air Conditioning

The workstations shall provide ventilation for the equipment identified in section 5.1.

4.6 Grounding, Bonding, Shielding, and Lightning Protection

Grounding, bonding, shielding, and lightning protection shall be in compliance with FAA-G-2100 and FAA-C-1217.

4.7 Cables

Workstations shall provide bottom entry for cable access from beneath a raised floor.

4.8 Hazardous Materials

Hazardous materials shall not be used excluded from in the AFSS OASIS workstations and operator chairs.

4.9 Power Systems and Commercial Power - N/A

4.10 Telecommunications - N/A

4.11 Special Considerations

The AFSS OASIS workstation installation shall comply with seismic requirements specified in Volume 2 of the Uniform Building Code, Structural Engineering Design Provisions, 1997FAA-STD-032.

5.1 Integration With Other NAS (and Non-NAS) Elements

5.1.1 The workstations shall use modular construction features to allow future equipment replacement or rearrangement without modification to the workstation structure.

5.1.2 Equipment Configuration

a. The Preflight workstation shall provide space for the installation of the following equipment:

2 - OASIS monitors positioned side-by-side (20"H x 19"W x 21"D;wt 20 lb.lbs.)

1 - standard 101-key keyboard (18"W x 2"H x 6"D, wt 1lb.)

1 - OASIS pointing device/mouse (7" x 7")

1 - OASIS Pentium class PC (18"H x 7"W x 17"D; 20 lb.lbs.)

1 - BCS Automatic Call Distributor (ACD) (9"L x 6.75"W x 3.5"D; 1.5 lb.lbs.)

1 - Headset Jack Panel (6"W x 3"H x 9"D;1 lb.)

b. The Flight Data workstation shall provide space for the installation of the following equipment:

2 - OASIS monitors positioned side-by-side (20"H x 19"W x 21"D;wt 20 lb.lbs.)

1 - standard 101-key keyboard (18"W x 2"H x 6"D, wt 1lb.)

1 - OASIS pointing device/mouse (7" x 7")

1 - OASIS Pentium class PC (18"H x 7"W x 17"D; 20 lb.lbs.)

1 - BCS Automatic Call Distributor (ACD) (9"L x 6.75"W x 3.5"D; 1.5 lb.lbs.)

1 - Headset Jack Panel (6"W x 3"H x 9"D;1 lb.)

Weather Observation Equipment

1 to 2 - 15" monitors (16"H x 16"W x 18"D;wt 20 lb.)

1 to 2 - standard 101-key keyboards (18"W x 2"H x 6"D, wt 1lb.)

c. The Flight Watch workstation shall provide space for the installation of the following equipment:

2 - OASIS monitors positioned side-by-side (20"H x 19"W x 21"D;wt 20 lb.lbs.)

1 - standard 101-key keyboard (18"W x 2"H x 6"D, wt 1lb.)

1 - OASIS pointing device/mouse (7" x 7")

1 - OASIS Pentium class PC (18"H x 7"W x 17"D; 20 lb.lbs.)

1 - BCS Automatic Call Distributor (ACD) (9"L x 6.75"W x 3.5"D; 1.5 lb.lbs.)

1 - Headset Jack Panel (6"W x 3"H x 9"D;1 lb.)

2 - ICSS 24-frequency panels (Denro 6"x 18" or Litton 11.3" x 18.8";wt 35 lb.)

d. The Inflight workstation shall provide space for the installation of the following equipment:

2 - OASIS monitors positioned side-by-side (20"H x 19"W x 21"D;wt 20 lb.lbs.)

1 - standard 101-key keyboard (18"W x 2"H x 6"D, wt 1lb.)

1 - OASIS pointing device/mouse (7" x 7")

1 - OASIS Pentium class PC (18"H x 7"W x 17"D; 20 lb.lbs.)

1 - BCS Automatic Call Distributor (ACD) (9"L x 6.75"W x 3.5"D; 1.5 lb.lbs.)

1 - Headset Jack Panel (6"W x 3"H x 9"D;1 lb.)

4 - ICSS 24-frequency panels (Denro 6"x 18" or Litton 11.3" x 18.8";wt 35 lb.)

1 - Digital Altimeter Setting Indicator (3"H x 4"W x 12"D; wt 3 lb.)

 

Analog Wind Equipment

Speed gauge (4" round; wt 12 lb. )

Direction gauge (4" round; wt 12 lb.)

Weather Observation Equipment

1 to 2 - 15" monitors (16"H x 16"W x 18"D;wt 20 lb.)

1 to 2 - standard 101-key keyboards (18"W x 2"H x 6"D, wt 1lb.)

1 - Airport Lighting Equipment (18" x 12"; wt 20 lb.)

1 to 6 - Direction Finding Equipment (24" x 8"; 20 lb.)

2 - Hazardous Inflight Weather Advisory Service panels (5" x 4"; wt 10 lb.)

2 - Transcribed Weather Broadcast panels (5" x 4"; wt 10 lb.)

e. The Supervisory workstation shall provide space for the installation of the following equipment:

2 - OASIS monitors positioned side-by-side (20"H x 19"W x 21"D;wt 20 lb.lbs.)

1 - standard 101-key keyboard (18"W x 2"H x 6"D, wt 1lb.)

1 - OASIS pointing device/mouse (7" x 7")

1 - OASIS Pentium class PC (18"H x 7"W x 17"D; 20 lb.lbs.)

1 - BCS Automatic Call Distributor (ACD) (9"L x 6.75"W x 3.5"D; 1.5 lb.lbs.)

1 - Headset Jack Panel (6"W x 3"H x 9"D;1 lb.)

4 - ICSS 24-frequency panels (Denro 6"x 18" or Litton 11.3" x 18.8";wt 35 lb.)

1 - Engine Generator Switch Panel (10" x 12"; wt 10 lb.)

1 - Door Security/Closed Circuit TV/door toggle switch (10"H x 10"W x 18"D; wt 15 lb.)

1 - Voice Recorder Monitor panel (10" x 12" x 6"D; wt 1 lb.)

ICSS Management Information System

1 to 2 - 15" monitors (16"H x 16"W x 18"D;wt 20 lb.)

1 to 2 - standard 101-key keyboards (18"W x 2"H x 6"D, wt 1lb.)

1 to 2 CPUs (18"H x 7"W x 7"D, wt 20 lb.)

ICSS Resource Management Equipment

1 - monitor (15" x 17"; wt 20 lb.)

1 - standard 101-key keyboard (18"W x 2"H x 6"D, wt 1lb.)

Weather Observation Equipment

1 to 2 - 15" monitors (16"H x 16"W x 18"D;wt 20 lb.)

1 to 2 - standard 101-key keyboards (18"W x 2"H x 6"D, wt 1lb.)

5.2 Software Integration - N/A

5.3 Spectrum Management - N/A

5.4 Standardization - N/A

6.1 Human/Product Interface

6.1.1 The workstations shall meet the human factors design guidelines established in Government and industry guidelines including ANSI, Uniform Federal Accessibility Standards, and the Americans with Disabilities Act and Appendix A, Human Factors Design Guidelines. In the event of conflict, Appendix A, Human Factors Design Guidelines, shall take precedence.

6.1.2 The positioning of the flight service equipment within the workstations shall meet the human factors requirements established in Government and industry guidelines including ANSI, Uniform Federal Accessibility Standards, and the Americans with Disabilities Act.

6.1.3 The workstations shall provide maintenance access to allow equipment removal and installation from both the front and rear of the workstation.

6.2 Employee Safety and Health

6.2.1 Workstations shall comply with FAA Order 3900.19A, Chapter 1, Paragraphs 7e.

6.2.2 Workstation maintenance and operations procedures shall meet the requirements of Title 29 CFR Part 1910, General Industry Standards, and Title 29 CFR Part 1926, Construction Standards.

6.2.3 Workstations shall be designed to permit removal and replacement of installed equipment by one person.

6.2.4 The installation of any equipment into the workstations shall be OSHA compliant.

6.3 Specialized Skills and Capabilities -N/A

7.1 Physical Security - N/A

7.2 NAS Information Security - N/A.

7.3 Personnel Security - N/A

8.1 Staffing - N/A

8.2 Supply Support

8.2.1 The AFSS OASIS workstations shall be delivered with initial site and depot spares required to facilitate repair and restoration. as determined by accepted analytical methodologies approved by the FAA. The Logistics Information System (LIS) will be the standard means of requisition and item management.

8.2.2 A support plan shall be developed which describes the plans for obtaining, cataloguing, receiving storing and issuing items of supply shall be documented in the workstation support plan.

8.3 Support Equipment

No new specialized tools or support equipment shall be required for the maintenance of the workstations without prior approval of the cognizant ATS organization.

8.4 Technical Data

8.4.1 An analysis shall be performed to determine the technical data requirements (e.g. manuals, drawings, installation procedures) needed to support the workstations over its intended lifecyle.

8.4.2 A support plan shall be developed which describes the plans for obtaining and distributing the required workstation technical data.

8.5 Training and Training Support

8.5.1 Air Traffic Training - N/A

8.5.2 Airway Facilities Training

8.5.2.1 Training shall be conducted to provide AF technicians with the knowledge and skills required to perform required on-site maintenance on the workstations.

8.5.2.2 The training shall be conducted on-site during the implementation of the workstations at the AFSS.

8.6 First and Second Level Repair

of the AFSS OASIS workstations shall be performed by AF maintenance personnel.

8.6.2 Second Level (depot) Maintenance - N/A

8.7 Packaging, Handling, Storage, and Transportation

8.7.1 Packaging, handling, storage and transportation shall be in accordance with ASTM-D3951, Standard Practice for Commercial Packaging.

8.7.2 Workstations shall be capable of being stored under the following conditions:

Temperature range: -10� to 50� C

Relative Humidity: Up to 100% (including condensation due

to temperature changes)

Altitude: 0 to 50,000 feet above sea level

8.8 Disposal

8.8.1 A disposal plan shall be developed in accordance with FAA Order 4800.2C.

8.8.2 The disposal plan shall describe disposal of the existing M1FC workstations being replaced by the AFSS OASIS workstations shall be accomplished as part of the workstation replacement effort.

8.8.3 The disposal plan shall describe the future disposal of the AFSS OASIS workstations.

9.1 Critical Operational Issues

Testing shall be conducted to ensure that functional performance requirements can be met in a operational environment, and to resolve the following Critical Operational Issues (COI):

Note: Test planning and conduct will involve all the stakeholders.

COI 1: Do AFSS OASIS workstations allow proper interface and operation of equipment and systems?

COI 2: Do AFSS OASIS workstations disrupt or degrade AFSS operations?

COI 3: Do AFSS OASIS workstations provide the required level of maintainability?

COI 4: Can AFSS OASIS workstations and installed equipment be maintained without disruption or degradation of current AFSS operations?

COI 5: Do AFSS OASIS workstations Computer Human Interface (CHI) characteristics effectively and suitably support AT and AF operations?

COI 6: Is AF training sufficient to allow effective operation and maintenance of the AFSS OASIS workstations?

9.2 Test and Evaluation.

Evaluation of the AFSS OASIS workstations shall be conducted in accordance with Acquisition Management System (AMS) test and evaluation guidance.

9.2.1 The Weather/Flight Service Systems Integrated Product Team (IPT) will lead the evaluation to verify contractual, operational requirements and COIs.

9.2.2 The evaluation shall verify that the workstations meet all requirements such as, but not limited to, Title 29 CFR, Title 40 CFR, and other applicable orders and directives.

10.0 IMPLEMENTATION AND TRANSITION

10.1 The workstation removal and installation process and associated activities shall be described in a Program Implementation Plan (PIP) developed in accordance with FAA-STD-036.

10.2 The PIP shall contain information on the removal and installation strategies and plans, the disposition of the M1FC consoles, removal and re-installation of the flight service equipment, funding, and impacts to the facility and personnel.

10.3 The PIP shall include a Generic Site Implementation Plan (GSIP) which contains a list of activities to be completed, identifies the personnel or organizations responsible for completing each task, and provides a schedule for activities.10.1 A Program Implementation Plan (PIP) shall be developed in accordance with FAA-STD-036.

10.2 The PIP shall describe removal of the flight service equipment from the existing M1FC workstations, removal of the M1FC workstations from the site, installation and checkout of the replacement AFSS workstations and the re-installation of the flight service equipment within the replacement workstations.

10.3 The PIP shall describe the plans for the transition from the existing M1FC workstations to the AFSS replacement workstations in a manner that will cause minimal disruption of AFSS flight service operations.

11.0 QUALITY ASSURANCE

11.1 Quality conformance evaluations as described in FAA-G-2100 shall be conducted to verify that the workstations are in accordance with the specified requirements.

11.2 Quality conformance evaluations shall include, but are not limited to, visual inspections and functional evaluations.

12.1 Software Configuration Management - N/A

12.2 Hardware Configuration Management

A workstation configuration management plan shall be developed that describes the process that will be used to control and document the configuration of the workstations.

12.3 Facility Configuration Management - N/A

12.4 Documentation Configuration Management

The configuration management of documentation delivered with the workstation (e.g. drawings, manuals, etc.) shall be addressed in the workstation configuration management plan.

13.0 IN-SERVICE MANAGEMENT

The product baseline for the AFSS OASIS workstations shall be updated as a result of technology refreshment, P³I, upgrade Engineering Change Proposals (ECPs), NAS Change Proposals (NCPs), and Requests for Deviation and Waiver (RDW).

The following sections are excerpted from:

Wagner, D., Birt, J. A., Snyder, M. D., & Duncanson, J. P. (1996). Human factors design guide: For the acquisition of commercial-off-the-shelf subsystems, non-developmental items, and developmental items (DOT/FAA/CT-96/1). Atlantic City International Airport: Federal Aviation Administration Technical Center.

Please refer to that document for further explanations, exhibits, and definitions. These sections provide guidance as to the procurement of commercial-off-the-shelf workstations and furniture for the Operational and Supportability Implementation System (OASIS).

9.4 Common working positions. To size and design workplaces, designers draw upon anthropometric information about the population of users. Data for design use representing common working positions and mobile working positions are found in this section. These data supplement the fundamental anthropometric data found in section 14 of the Human Factors Design Guide (HFDG).

9.4.1 Static dimensions for common body positions. Static body positions along with 5th and 95th percentile criteria are given in exhibit 9.4.1 of the HFDG. Clearance dimensions shall not be less than that for the 95th percentile male; nor shall limiting dimensions be greater than the dimensions for the 5th percentile female.

9.4.4 Seated workplaces. In this section, a discussion to help exploit the advantages of the seated position is followed by general guidelines for ensuring seating compatibility with tasks. The section includes guidelines for office seating design, and for seat cushion, armrest, and footrest design. Designers can exploit the following advantages of seated positions:

Seated positions reduce workload by helping maintain the body position and carry body weight.

Seats provide comfortable positions that promote long-term focused attention on activities and information in the nearby workspace.

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Seating limits reach with both arms and hands.

Seating can be designed to swivel and move on rollers to extend visual, reach, and communications access.

The main disadvantages of seated work positions are that seated workers can apply less arm forceand smaller arm movements than standing workers. In addition, seated workers have more accessibility to equipment and are able to move about to reduce fatigue and boredom.

9.4.4.1 Seated workplace guideline. Workplace seats should provide support for and stabilize the worker’s body. The seat should permit visual, reach, and communications access so the intended work tasks can be performed efficiently and without interference. Neither the shape of the seat nor the materials used in the seat should prevent the worker from adjusting body position in the seat for task activities or for comfort.

9.4.4.2 Seat compatibility. Seats should be compatible with the work tables, benches, desks, workstations, equipment, tools, controls, and displays that are necessary to the tasks.

9.4.4.3 Swivels and rollers. For most jobs and tasks that do not require heavy work and where seated positions are appropriate, swivel capability and caster rollers are desirable for seat ingress and egress and task performance throughout the workplace.

9.4.4.4 Seating dimensions. General seated workplace dimensions are given and illustrated in exhibit 9.4.4.4 of the HFDG. Seat designs and selections should meet or exceed minimum values, should provide adjustment ranges, and should provide fixed and preferred values when these are compatible with the population and tasks to be performed.

9.4.4.5 Knee space. The preferred knee space, as shown in exhibit 9.4.4.4, should be 640 mm (25 in) in height. Where equipment packaging permits, knee space and associated leg space should be attained by sloping the workstation surface under the working or writing surface. A footrest will increase the needed knee space.

9.4.4.6 Seat cushioning. Seats should be cushioned whenever workers must remain seated for more than an hour at a time, or for more than 20% of their working time. Good seat cushioning should:

have flat, firm shape with enough softness to deform,

have resilient material under the cushion to absorb shocks,

support body weight, primarily around the two bony points of the pelvis,

tilt backward 5-7 degrees so the seat (rather than the user’s muscles) supports the back,

be shaped to follow the inward curve of the lower back, and provide adequate support for it, to relieve strain of the back muscles,

avoid applying pressure under the thighs,

incorporate perforated or ventilated materials, to prevent hotness or sweating, and

allow the sitter to shift positions.

9.4.4.7 The use of armrests. Workplace seating should provide armrests so that the elbows can support some upper body weight, unless the rests would be incompatible with the tasks. Armrests should be undercut to allow space for the hips and thighs. Exhibit 9.4.4.4 provides fixed armrest dimensions. Removable or adjustable armrests should be considered when removal is necessary for some primary tasks. The preferred adjustable range is from 190 to 280 mm (7.5 to 11 in) above the compressed seat surface. They should be at least 200 mm (8 in) in length. When seated tasks include the use of a tracking control for frequent or continuous control, the armrest should support the worker’s arm in the same plane as the control.

9.4.4.9 Footrests. Whenever workers must sit for extended sitting periods in seats higher than 460 mm (18 in) or work with work surfaces higher than 760 mm (30 in), they should have a footrest which may be designed into the chair or stool. When footrests are separate items, they should not be allowed to interfere with traffic.

9.5 Standard workstation design. Standard workstation designs are addressed in this section. Recommended configurations for sit, sit-stand, and stand workstations are given, and horizontal wrap-around and vertically stacked segment alternatives are provided. Additional workstations for teams that monitor ongoing processes are addressed in this section.

9.5.1 Sit, sit-stand, and stand workstations. The guidelines that follow are to be used to gain the benefits and potential cost savings inherent in standard workstations, units, and racks. In some cases planned usage may necessitate unique design solutions.

9.5.1.1 Dimensions for workstation configurations. Exhibit 9.5.1.1 (a) of the HFDG lists five types of workstations for individuals and gives dimensions for alternative standard configurations. Selected configurations should conform to the dimensions listed and illustrated in exhibit 9.5.1.1 (b).

9.5.1.2 Selection of a standard workstation. Each workstation configuration should be selected to accommodate the following task-related variables:

visibility over the top of workstation,

user mobility (e.g., sit, sit-stand, or stand requirements),

control and display demand for panel space (for example, display legibility, control accessibility),

volume of space necessary for leg room and essential equipment beneath the writing surface, and

communications demands of the tasks.

9.5.2 Horizontal wrap-around workstation alternatives. Whenever the panel space required for a seated workstation user exceeds that recommended in exhibit 9.5.1.1 (a), the special purpose horizontal wrap-around workstation presented in this section may be used. The concept for this alternative is illustrated in exhibit 9.5.2 of the HFDG.

This panel facilitates placing controls within the reach of the 5th percentile users.

9.5.2.2 Panel angles. The left and right segments should be placed at an angle, measured from the frontal plane of the central segment, so that these segments can be reached by the 5th percentile stationary operator.

9.5.2.3 Dimensions with vision over the top. Where vision over the top is required (thereby limiting vertical panel space), the width of the central segment shall not exceed 1.12 m (44 in), and that of the left and right segments shall not exceed 610 mm (24 in).

9.5.2.4 Width dimensions without vision over the top. Where vision over the top is not required (that is, where the total workstation height exceeds the seat height by more than 690 mm (27 in)), the width of the central segment shall not exceed 860 mm (34 in), and that of the left and right segments, if possible, shall not exceed 610 mm (24 in).

9.5.2.5 Viewing angle. The total required left-to-right viewing angle shall not exceed 190 degrees (see head and eye rotation in exhibit 7.2.1.6.8 of the HFDG). This angle should be reduced whenever possible through appropriate control-display layout.

9.5.3 Vertical stacked segments for workstations. Another alternative special-purpose workstation applies to the case where seeing over the top is not required and lateral space is limited. The concept for this individual seated user workstation is shown in exhibit 9.5.3 of the HFDG.

9.5.3.1 Panel division. Where direct forward vision over the top of the workstation is not required by a seated person and where lateral space is limited, the panel shall be divided into three vertical stacked segments whose surfaces are perpendicular to the operator’s line of sight when the head is moved up or down slightly.

9.5.3.2 Height. The center of the central segment should be 800 mm (31.5 in) above the seat reference point. If feasible, the height of this segment shall not exceed 530 mm (21 in).

9.7 Accommodating people with disabilities: Accessible elements and space. The Americans with Disabilities Act Handbook provides accessibility "guidelines" to be applied during design, construction, and alteration of buildings and facilities to the extent required by regulations issued by Federal Agencies including the Department of Justice. The present subsection refers to those parts of the Handbook that correspond with the workplace topics of section 9. If acquisitions or modifications include workspace design for jobs that are subject to being filled by Americans with disabilities, the workspace aspects of the handbook apply. To comply with the following rules, human factors professionals refer to the handbook itself to ensure that all relevant topics are applied to specific system or equipment.

9.7.2 Reasonable accommodation of workspace to an individual. If an individual employee with disabilities is qualified and selected for a job, Title 1 of the ADA requires "reasonable accommodations" of the job and workspace to the individual. Modifications of the workspace to permit maneuvering and reaching controls, shelves, and reference materials should be provided, as necessary. Appendix A, Section 4.1.1, Application, to the ADA Accessibility Guidelines (ADAAG) requires that wherever a series of individual workstations of the same type (for example, laboratories, service counters, ticket booths) at least one or five percent of the work stations should be constructed so that an individual with disabilities can maneuver within the workspace.

13.4 Illumination. Criteria for appropriate illumination cannot be satisfied merely by providing a sufficient amount of light to perform tasks or by providing emergency lighting (approximately 32 lux) to enable personnel to operate important controls or to find the exit. The following factors need to be considered:

the brightness contrast between each visual task object and its background,

the glare from work surfaces and light sources,

the level of illumination required for the most difficult tasks,

the color composition of the illumination source and the equipment surfaces,

the time and accuracy required in task performance, and

the possible variations in operating conditions (such as outdoor panel blackout operation or outdoor panel visibility under bright sunlight) that may affect the lighting system, the task, or the personnel.

13.4.1 General. In addition to the following illumination guidelines, see the "Lighting Handbook from the Illuminating Engineering Society", for general lighting design foot-candlefootcandle levels and formulas.

13.4.1.1 General and supplementary lighting. Both general and supplementary lighting shall be used as appropriate to ensure that illumination is compatible with each operation and maintenance task situation.

13.4.1.2 Dimming capability. A light dimming capability shall be provided.

13.4.1.3 Illumination in workplaces. As a general rule, illumination in workplaces should eliminate glare and shadows that interfere with prescribed tasks.

13.4.2.1 Lighting level. The lighting level shall be measured on the work surfaces, (30 inches above the floor in the absence of work surfaces), or at visual interfaces, (for example, CRT and panels), where appropriate.

13.4.2.2 Illumination. Workplace illumination shall be appropriate to the tasks to be accomplished. See exhibit 13.4.2.2 in the HFDG for illumination requirements.

13.4.2.3 Glare. Lighting sources shall be designed and located to avoid creating glare from working and display surfaces, as viewed from any normal working position.

13.4.4 Glare from light sources. One of the most serious illumination problems is glare from surfaces. Relatively bright light shining into the observer’s eyes as he or she tries to observe a dim visual field, and reflected glare from work surfaces are common causes of reduced performance in visual tasks. Glare not only reduces visibility of objects in the field of view but causes visual discomfort.

13.4.4.1 Glare from artificial light sources. The following measures shall be taken to avoid glare from artificial light sources:

Locate light sources so that they do not shine directly at personnel. Light sources shall not be located within 60� in any direction from the center of the visual field.

If additional lighting is needed, use dim light sources rather than bright ones.

Use polarized light, shields, hoods, lens, diffusers, or visors.

Use indirect lighting where possible.

Ensure that the maximum to average luminance ratio does not exceed 5:1 across the viewing area. Six test readings shall be taken in the work area to determine the average luminance of the area.