DOT/FAA/AR-05/41 

Office of Aviation Research 

Washington, D.C. 20591

Design and Installation of 

Flasher Baffles at the 

Arcata/Eureka Airport 

James W. Patterson, Jr. 

August 2005 

Final Report 

This document is available to the U.S. public 

through the National Technical Information 

Service (NTIS), Springfield, Virginia 22161. 

U.S. Department of Transportation 

Federal Aviation Administration
NOTICE 

This document is disseminated under the sponsorship of the U.S. 

Department of Transportation in the interest of information exchange. The 

United States Government assumes no liability for the contents or use 

thereof. The United States Government does not endorse products or 

manufacturers. Trade or manufacturer's names appear herein solely 

because they are considered essential to the objective of this report. This 

document does not constitute FAA certification policy. Consult your local 

FAA airports office as to its use. 

This report is available at the Federal Aviation Administration William J. 

Hughes Technical Center's Full-Text Technical Reports page: 

actlibrary.tc.faa.gov in Adobe Acrobat portable document format (PFD). 
Technical Report Documentation Page

1. Report No.

DOT/FAA/AR-05/41

2. Government Accession No. 3. Recipient's Catalog No.

5. Report Date

August 2005

 4. Title and Subtitle 

DESIGN AND INSTALLATION OF FLASHER BAFFLES AT THE 

ARCATA/EUREKA AIRPORT 6. Performing Organization Code

ATO-P

7. Author(s)

James W. Patterson, Jr. 

8. Performing Organization Report No. 

9. Performing Organization Name and Address

Federal Aviation Administration 

William J. Hughes Technical Center 

10. Work Unit No. (TRAIS)

Airport and Aircraft Safety 

Research and Development Division 

Airport Technology Research and Development Branch 

Atlantic City International Airport, NJ 08405

11. Contract or Grant No.

12. Sponsoring Agency Name and Address

U.S. Department of Transportation 

Federal Aviation Administration

13. Type of Report and Period Covered

 Final Report

Airways Facilities Division, AWP-400 

Washington, DC 20591

14. Sponsoring Agency Code

 AWP-400

15. Supplementary Notes

Thomas Paprocki, Renee Frierson, and Oswaldo Valdivieso of HiTec Systems provided technical support throughout the course of 

this evaluation.

16. Abstract

The medium intensity approach lighting system with runway alignment indicator lights operating on runway 32 at the 

Arcata/Eureka Airport in McKinleyville, California, was causing a severe glare hazard to motorist driving on a nearby highway that 

crossed through the system, approximately 1400 feet from the end of the runway. Specifically, the glare was caused by highintensity light output from the strobe portion of the Approach Lighting System. The Western-Pacific Region, Airway Facilities 

Division requested the Airport Technology Research and Development Branch to investigate and provide possible solutions to 

eliminate the hazard. 

Based on the geometry of the roadway and the Approach Lighting System, it was determined that a series of baffles installed on 

three of the five strobe lights would be the most effective way to block the light from being projected directly into the motorists’ 

eyes. Engineers designed, developed, and constructed three different aluminum baffles specifically for the situation at the 

Arcata/Eureka Airport. Each of the three baffles differed slightly in design, as they were optimized for each of their respective 

locations within the Approach Lighting System. 

Ground and flight evaluations, which included the use of motor vehicles and aircraft, were conducted during both day- and 

nighttime conditions to determine if the glare hazard had been eliminated without affecting the usability of the lights for 

approaching aircraft. The results of the evaluations showed that the baffles had eliminated the glare hazard to motorist on the 

highway without reducing the essential approach guidance needed by pilots. 

17. Key Words: 

MALSR, Strobe Lights, RAILS, Visual Guidance, Baffle 

18. Distribution Statement 

This document is available to the public through the 

National Technical Information Service (NTIS), 

Springfield, Virginia 22161.

19. Security Classif. (of this report)

 Unclassified 

20. Security Classif. (of this page)

 Unclassified

21. No. of Pages

 16

22. Price

Form DOT F1700.7 (8-72) Reproduction of completed page authorized 
TABLE OF CONTENTS 

Page 

EXECUTIVE SUMMARY vii 

INTRODUCTION 1 

Purpose 1 

Objective 1 

Background 1 

Related Activities and Documentation 2 

PROCEDURES 3 

The Initial Site Inspection Visit 3 

Preparation 5 

Installation Site Visit 6 

RESULTS 7 

SUMMARY 8 

CONCLUSIONS 9 

iii
LIST OF FIGURES 

Figure Page 

1 Plot Plan of the Runway 32 Approach Area 1 

2 Roadway Traversing the ALS System 2 

3 Prototype A Baffle 4 

4 Prototype B Baffle 5 

5 Upward View of Larger Baffle as Installed 7 

iv
LIST OF ACRONYMS 

ACV Arcata/Eureka Airport 

ALS Approach Lighting System 

FAA Federal Aviation Administration 

ILS Instrument Landing System 

MALSR Medium Intensity Approach System with Runway Alignment Lights 

v/vi
EXECUTIVE SUMMARY

The Federal Aviation Administration (FAA) Office of Aviation Research, Airport Technology 

Research and Development Branch, ATO-P, conducted this project at the request of the WesternPacific Region, Airway Facilities Division, AWP-400. The task was to obtain and install light 

baffles for the runway alignment indicator lights (RAIL) portion of the Medium Intensity 

Approach Lighting System (MALS) at the approach end of runway 32 at the Arcata/Eureka 

Airport in Arcata, California. Assistance was requested to remedy a situation in which local 

residents had filed several complaints stating that the system crosses a public road and that the 

glare from the sequenced flasher was distracting and hazardous. 

Airport Technology Research and Development Branch personnel were sent to the site to survey 

the installation, and as a result, developed preliminary plans to fabricate baffles to prevent the 

light from the RAIL units from striking the roadway. After the baffles were fabricated at the 

FAA William J. Hughes Technical Center, the team returned to the site for installation and 

testing. This installation is unique in that the roadway climbs up to the MALS system, making it 

very difficult to mask the light for the roadway at both short and long distances without 

impacting the usable light required in the approach zone. This report describes the steps taken to 

assess the situation, fabricate the baffles, and install and test them at the Arcata/Eureka Airport. 

Ground and flight evaluations conducted by the Airport Technology Research and Development 

Branch verified that the installed baffles had eliminated the hazard without reducing the essential 

approach guidance needed by pilots. 

vii/viii
INTRODUCTION 

PURPOSE. 

The purpose of this effort was to provide a solution to a road hazard situation existing at the 

Arcata/Eureka Airport (ACV). The project was initiated and sponsored by the Federal Aviation 

Administration (FAA) Western-Pacific Region Airway Facilities Division, AWP-400, and 

undertaken by the FAA Office of Aviation Research, Airport Safety Technology Research and 

Development Branch. 

OBJECTIVE. 

The objective of this research effort was to determine if a baffle device could be designed that 

would block nuisance light from distracting drivers operating their vehicles on a public road that 

crossed the final approach of runway 32 at ACV. In addition, the objective was to fabricate, 

install, and flight test the baffles, and once installed, to ensure that the usable signal was in no 

way affected for approaching aircraft. 

BACKGROUND. 

A well-traveled public road, Central Avenue in McKinleyville, California, passes to the east of 

the Arcata/Eureka Airport immediately adjacent to the airport boundary fence. The road also 

passes directly through the runway 32 approach area of the airport at a very acute angle of 

approximately 30 degrees to the Approach Lighting System (ALS), and passes beneath the lights 

at a point only 1700 feet from the runway threshold (figures 1 and 2). 

FIGURE 1. PLOT PLAN OF THE RUNWAY 32 APPROACH AREA 

1
1,600 ft. 

Location 

1,800 ft. 

Location 

2,000 ft. 

Location

FIGURE 2. ROADWAY TRAVERSING THE ALS SYSTEM 

While the steady-burning lights of the medium intensity approach lighting system with runway 

alignment indicator lights (MALSR) are far enough from the road, they pose no visual hazard to 

passing motorists, but the high-intensity condenser discharge (strobe) lights located immediately 

adjacent to the road on either side have occasioned numerous complaints. They are especially 

irritating when set to the highest intensity setting for pilots executing instrument approaches 

during inclement weather. The Arcata/Eureka Airport is noted as having extremely frequent 

occurrences of heavy fog during early morning, high-vehicle traffic along this road. 

The requesting office felt that the strobe lights might be baffled or shielded to cut off light from 

the motorists’ eyes, while still maintaining the essential visual guidance for pilots. 

RELATED ACTIVITIES AND DOCUMENTATION. 

While the Airport Safety Technology Research and Development Branch has executed several 

quick response projects for baffling strobe lights, either in the Runway End Identifier Light or 

ALS configurations, each effort was to solve a unique, site-specific situation. No standard 

2
configuration for strobe baffles has been developed, and virtually no specific documentation can 

be identified herein. The following reports do, however, describe several approaches to the 

problem used in the past. 

• Letter Report No. NA-76-62-LR, “Evaluation of MALS/RAILS Baffles,” December 

1976. 

• Technical Note DOT/FAA/AR-TN01/61, “Installation of Runway End Identifier Light 

Baffles at the Medina, Ohio Municipal Airport,” June 2001. 

PROCEDURES

THE INITIAL SITE INSPECTION VISIT. 

A project team from the FAA Airport Safety Technology Research and Development Branch 

traveled to the Arcata/Eureka Airport, July 6 through July 8, 2004, to investigate the problem and 

to collect data for later use in designing baffles at the William J. Hughes Technical Center. 

The team had several different rough prototype trapezoidal-shaped baffles that were prepared for 

previous projects and mounted them temporarily on the three most critical strobe towers (figure 

2) in an attempt to establish the degree of baffling required. Ground observations were made 

along the affected road segment, both with and without temporary baffles mounted. Vertical and 

horizontal measurements were obtained from all critical observation points. 

Precise theodolite measurements were taken at the site to establish acquisition angles from 

different points on the roadway and to determine the optimal orientation, size, and design of the 

baffle devices that would be needed to correct the problem. Actual measurements taken with a 

theodolite resulted in the following angular measurements: 

• Angle A H: 27o 44′ 00′′

Horizontal angle of the right side of the road with respect to the centerline of the runway 

• Angle B H: 26o 11′ 40′′

Horizontal angle of the left side of the road with respect to the centerline of the runway 

• Angle C V: 5o 35′ 00′′

Vertical angle from the roadway to the ALS unit, directly in alignment with the runway 

centerline (approximately 100 ft away from fixture) 

• Angle D V: 2o 47′ 20′′

Vertical angle from the roadway to the ALS unit at the lowest point on the road where the 

ALS unit is first visible (0.35 miles) 

After completing the theodolite measurements, it was decided that the strobe fixtures on each 

side of the road, at 1600, 1800, and 2000 feet from the runway threshold, would be temporarily 

fitted with the prototype baffles. Addressing the problem with the strobe unit at 1600 feet from 

3
the runway threshold, the first baffle (figure 3) was relatively long in design, which is optimal for 

situations where the targeted area is somewhat distant from the light fixture. The problem in this 

situation, however, was that the road is to the side of the fixture, and a great amount of light was 

still visible over the side of the baffle directly from the flasher light unit. When the baffle was 

turned towards the road, approximately 26 degrees to the right of the extended runway 

centerline, the baffle blocked most of the light. In this position, however, the baffle did not 

block the light from immediately in front of the fixture. It was determined that a fan-shaped 

baffle design might be more effective, as it would likely block light from both in front of the 

fixture and from the road 26 degrees to the right. 

FIGURE 3. PROTOTYPE A BAFFLE 

The second smaller baffle design was then tried at the same location (figure 4). Based on 

pictures that were provided by the local Airway Facilities group, it was thought that a shorter, 

wider baffle would be better suited in close proximity to the roadway. Once mounted to the light 

unit, however, it was quickly determined that the longer unit that was first tried would be more 

appropriate for blocking the light from the affected area. 

The smaller baffle was then tried on the light unit at 1800 feet from the runway threshold, which 

is on the opposite side of the roadway from the airport, and yielded much better results. As can 

be seen in figure 4, the baffle was mounted to the side of the light fixture, which was very 

effective at masking the light from the immediate side of the fixture, precisely where the 

roadway was in relation to the fixture. 

4
FIGURE 4. PROTOTYPE B BAFFLE 

The prototypes were tested in various configurations until an optimal orientation with respect to 

the oncoming traffic on the road was obtained. In addition, large cardboard panels were taped to 

the baffle to simulate a larger baffle design. Black tar paper was also added to the baffle to 

reduce the amount of reflection from the baffle itself. 

Under full darkness, the team returned to the site to observe how much of the light was blocked 

from the roadway with the prototype baffle installed. All present agreed that the baffles greatly 

reduced the amount of light visible, but that additional work would be necessary to properly 

construct a baffle specifically for this installation that would feature a wide angle to cover the 

+26 degrees of coverage area, have higher sides to block light to the sides of the fixture, and be 

constructed of black-painted aluminum to endure the harsh salt air environment prevalent in the 

Arcata area. 

The team also sketched and photographed the manner in which the strobes, and associated tower 

hardware, were mounted so as to be able to later design and fabricate suitable mounting 

hardware at the William J. Hughes Technical Center. A spare PAR56 strobe lamp retaining ring 

was also brought back to the William J. Hughes Technical Center with the thought that it might 

serve as a mounting surface for smaller baffles that could attach directly to the light unit. 

PREPARATION. 

As a result of the data obtained and observations made at the Arcata/Eureka Airport, the strobe 

unit (1600 feet from the runway 32 threshold) facing almost directly into the motorists’ eyes, 

would have to be fitted with a relatively large (2- to 3-foot long) dust-pan-shaped baffle. The 

baffle would need to be supported independently from the strobe light head by attachment to the 

tower tube and top cap portion of the tower structure itself. 

5
The other two strobe units, 1800 and 2000 feet from the runway threshold and on the far side of 

the road, actually faced away from the eyes of the motorists. It was only necessary to block the 

light directed sideways and rearward from the strobes. It was determined that smaller 

(approximately 1-foot long) baffles, again of the dust-pan shape, could be provided and attached 

directly to the strobe light retaining ring (i.e., directly to the strobe head). 

The smaller baffles were designed so that they could be rotated in a circular fashion on site 

before being permanently attached to the light head. In addition, they could also be adjusted 

vertically to vary the amount of light being directed to the ground. 

A larger baffle, of considerably greater weight and surface area, was designed to be attached to 

the top of the tower, directly below the strobe light fixture, and supported by aluminum channels 

bolted from a lower position on the tower to the front sides of the baffle. The vertical angle of 

the baffle could, thus, be adjusted on site to cut off any direct observation of the strobe by 

passing motorists by simply sliding the tower end of the supporting channels up or down. 

The three baffles were then fabricated from lightweight aluminum, primed, and painted flat 

black. All necessary mounting supports, attachment devices, and related hardware were either 

fabricated at the William J. Hughes Technical Center or purchased at a local hardware store. 

INSTALLATION SITE VISIT. 

Once fabrication and shipment of the baffles had been accomplished, the team traveled to the 

Arcata/Eureka Airport on January 10, 2005. 

Installation of the large baffle at the location inside the boundary fence was accomplished first, 

and necessitated some adjustment so that it could be oriented almost parallel to the road, facing 

south, while keeping the strobe light itself facing directly toward the path of approaching aircraft. 

An additional small bracket was fabricated and attached on site to stabilize the baffle in the 

desired direction. The baffle shown in figure 5 resembles the previously used larger prototype 

baffle, with the exception that it was made somewhat longer and with a wider lip (i.e., more fanshaped). When comparing figures 3 and 5, the larger overall shape and wider lip is evident. 

The two smaller baffles were then attached to the strobe light units on the other side of the road 

to the east. This was a relatively easy task, since the baffles had been designed to attach directly 

to the lamp retaining ring with the existing wing nut fasteners. The baffle was rotated 

approximately 30 degrees clockwise prior to mounting to further shield the light from motorists 

approaching from the south. The vertical elevation was left at the maximum setting to cut off 

light from below the center of the lamp, but was changed after flight tests, as will be explained in 

the Results section. The smaller baffles used in the final installation are so similar in design to 

the prototype version that the prototype installation shown in figure 4 serves to depict both units 

as mounted. 

6
FIGURE 5. UPWARD VIEW OF LARGER BAFFLE AS INSTALLED 

RESULTS 

A ground test, using a vehicle, was conducted during the afternoon of January 11th to determine 

whether the installed baffles were blocking off the direct strobe light emissions that proved to be 

distracting to passing motorists. Under partial sunlight conditions, virtually no evidence of the 

strobe flashes was perceived when driving in either direction along the road. 

A daytime flight test using a Cessna 172 general aviation single-engine aircraft was 

accomplished during the same afternoon. This aircraft was selected because observations can be 

made at very slow speeds while safely deviating considerably from the on-course glide path and 

localizer of the runway 32 Instrument Landing System (ILS). ILS localizer deviations up to and 

exceeding full-scale needle deflections were flown well beyond the point at which a pilot would 

have to abandon the approach and perform a go-around or missed approach. In addition, these 

left-right course deviations were accomplished while maintaining a two-dot fly-up ILS glide path 

signal, as verified by a three-red/one-pink precision approach path indicator (PAPI) visual signal. 

During the initial approaches, a slight decrease in the intensity of the strobe unit at the 1800-foot 

location was noted while flying the widest off-course deviations. Slight adjustments to the 

vertical positioning of the baffles on both strobes to the east of the road were requested via radio 

and resulted in restoring full intensity to the entire sequenced flashing display, commonly 

nicknamed the rabbit. 

Both the ground and flight tests were conducted again that evening in full darkness and relatively 

clear sky conditions. 

A test vehicle passing through the lighting system along the road revealed that only reflections 

off particles in the air above the strobe units could be detected, and that all direct light from the 

7
strobes were successfully masked from motorists traveling past the units. This was a significant 

reduction in perceived light, and one individual in the test vehicle remarked that “the lights from 

on-coming cars are much more of a distraction than the small amount of light from the strobes.” 

The flight test conducted during the same evening and under the same darkness and weather 

conditions produced results identical to those obtained during the daytime test flights. The entire 

sequenced flashing light display was fully visible at the extreme ILS glide path and localizer 

deviations (full localizer and two-dot fly-up glide path needle deflections). 

Various members of the Arcata/Eureka Systems Service Center also participated in the day- and 

nighttime evaluations from both the vehicle and aircraft. All participants were given the 

opportunity to provide comments on the performance of the baffles. At the conclusion of the 

evaluation activity, a final meeting was held at the Systems Service Center to discuss the results 

of the prior day’s evaluation. All participants felt that the effort had been successful and that the 

results were satisfactory. 

Within 1 month of the installation, follow-up telephone conversations with the manager of the 

Systems Service Center provided positive feedback on the results of the baffle installation. Both 

the FAA and local airport administration have indicated that they are very pleased with the 

results of the research effort. 

SUMMARY

Site surveys of the Arcata/Eureka Airport showed that baffles could be used in this situation, 

where a roadway crosses the final approach zone of the runway at distances as close as 100 feet 

from the inboard strobe fixture of the medium intensity lighting system with runway alignment 

indicator lights installation. 

The baffles can be fabricated from generally available metal/aluminum stock, requiring minimal 

bending and workmanship. Data collected from site visits was essential in designing the baffle 

to ensure that it blocked light from the proper areas. 

The installation procedure was very basic and required only a few minutes per fixture. 

Flight test efforts, from 8 miles out, on a simulated full-needle deflection approach, 2 degrees 

below the proper glide path, proved that the installed baffles performed as desired, only masking 

light from the ground, and not from the air. 

Evaluation efforts on the ground proved successful, as the strobe lights that, at one time, flashed 

on the roadway were deflected such that no direct light was visible from the roadway, 

approaching from either the north or south direction. 

8
CONCLUSIONS

Having completed the research, the following conclusions were made: 

• It was determined that the geometry of the runway and the approach lighting system in 

relation to the roadway was such that a baffle could effectively be used to mask the light 

from the roadway. 

• It was determined that the baffle devices that were fabricated and installed at the 

Arcata/Eureka Airport sufficiently masked the light from the roadway, but in no way 

affected any of the usable signal intended for use by approaching aircraft. 

9/10