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Pilot/Controller Glossary 

6/17/21 

hazardous terrain, obstructions, or noise abatement 
procedures. 

8. 

RAIL

 Runway Alignment Indicator Lights

 

Sequenced Flashing Lights which are installed only 
in combination with other light systems. 

9. 

ODALS

 Omnidirectional Approach Light-

ing System consists of seven omnidirectional 
flashing lights located in the approach area of a 
nonprecision runway. Five lights are located on the 
runway centerline extended with the first light 
located 300 feet from the threshold and extending at 
equal intervals up to 1,500 feet from the threshold. 
The other two lights are located, one on each side of 
the runway threshold, at a lateral distance of 40 feet 
from the runway edge, or 75 feet from the runway 
edge when installed on a runway equipped with a 
VASI. 

(Refer to FAA Order JO 6850.2, VISUAL 

GUIDANCE LIGHTING SYSTEMS.) 

b. 

Runway Lights/Runway Edge Lights

 Lights 

having a prescribed angle of emission used to define 
the lateral limits of a runway. Runway lights are 
uniformly spaced at intervals of approximately 200 
feet, and the intensity may be controlled or preset. 

c. 

Touchdown Zone Lighting

 Two rows of 

transverse light bars located symmetrically about the 
runway centerline normally at 100 foot intervals. The 
basic system extends 3,000 feet along the runway. 

d. 

Runway Centerline Lighting

 Flush centerline 

lights spaced at 50-foot intervals beginning 75 feet 
from the landing threshold and extending to within 75 
feet of the opposite end of the runway. 

e. 

Threshold Lights

 Fixed green lights arranged 

symmetrically left and right of the runway centerline, 
identifying the runway threshold. 

f. 

Runway End Identifier Lights (REIL)

 Two 

synchronized flashing lights, one on each side of the 
runway threshold, which provide rapid and positive 
identification of the approach end of a particular 
runway. 

g. 

Visual Approach Slope Indicator (VASI)

 An 

airport lighting facility providing vertical visual 
approach slope guidance to aircraft during approach 
to landing by radiating a directional pattern of high 
intensity red and white focused light beams which 
indicate to the pilot that he/she is “on path” if he/she 
sees red/white, “above path” if white/white, and 
“below path” if red/red. Some airports serving large 

aircraft have three-bar VASIs which provide two 
visual glide paths to the same runway. 

h. 

Precision Approach Path Indicator (PAPI)

 An 

airport lighting facility, similar to VASI, providing 
vertical approach slope guidance to aircraft during 
approach to landing. PAPIs consist of a single row of 
either two or four lights, normally installed on the left 
side of the runway, and have an effective visual range 
of about 5 miles during the day and up to 20 miles at 
night. PAPIs radiate a directional pattern of high 
intensity red and white focused light beams which 
indicate that the pilot is “on path” if the pilot sees an 
equal number of white lights and red lights, with 
white to the left of the red; “above path” if the pilot 
sees more white than red lights; and “below path” if 
the pilot sees more red than white lights. 

i. 

Boundary Lights

 Lights defining the perimeter 

of an airport or landing area. 

(Refer to AIM.) 

AIRPORT MARKING AIDS

 Markings used on 

runway and taxiway surfaces to identify a specific 
runway, a runway threshold, a centerline, a hold line, 
etc. A runway should be marked in accordance with 
its present usage such as: 

a. 

Visual. 

b. 

Nonprecision instrument. 

c. 

Precision instrument. 

(Refer to AIM.) 

AIRPORT REFERENCE POINT (ARP)

 The 

approximate geometric center of all usable runway 
surfaces. 

AIRPORT RESERVATION OFFICE

 Office 

responsible for monitoring the operation of slot 
controlled airports. It receives and processes requests 
for unscheduled operations at slot controlled airports. 

AIRPORT ROTATING BEACON

 A visual 

NAVAID operated at many airports. At civil airports, 
alternating white and green flashes indicate the 
location of the airport. At military airports, the 
beacons flash alternately white and green, but are 
differentiated from civil beacons by dualpeaked (two 
quick) white flashes between the green flashes. 

(See INSTRUMENT FLIGHT RULES.) 
(See SPECIAL VFR OPERATIONS.) 
(See ICAO term AERODROME BEACON.) 
(Refer to AIM.) 

PCG A