Aviation Cloud Forecast, or area forecast concerning
weather phenomena which are of operational interest
to all aircraft and potentially hazardous to aircraft
having limited capability because of lack of
equipment, instrumentation, or pilot qualifications.
AIRMETs concern weather of less severity than that
covered by SIGMETs or Convective SIGMETs.
AIRMETs cover moderate icing, moderate turbulence, sustained winds of 30 knots or more at the
surface, widespread areas of ceilings less than 1,000
feet and/or visibility less than 3 miles, and extensive
mountain obscurement.
(See AWW.)
(See CONVECTIVE SIGMET.)
(See CWA.)
(See SIGMET.)
(Refer to AIM.)

AIRPORT- An area on land or water that is used or
intended to be used for the landing and takeoff of
aircraft and includes its buildings and facilities, if
any.
AIRPORT ADVISORY AREA- The area within ten
miles of an airport without a control tower or where
the tower is not in operation, and on which a Flight
Service Station is located.
(See LOCAL AIRPORT ADVISORY.)
(Refer to AIM.)

AIRPORT ARRIVAL RATE (AAR)- A dynamic
input parameter specifying the number of arriving
aircraft which an airport or airspace can accept from
the ARTCC per hour. The AAR is used to calculate
the desired interval between successive arrival
aircraft.
AIRPORT DEPARTURE RATE (ADR)- A dynamic
parameter specifying the number of aircraft which
can depart an airport and the airspace can accept per
hour.
AIRPORT ELEVATION- The highest point of an
airport"s usable runways measured in feet from mean
sea level.
(See TOUCHDOWN ZONE ELEVATION.)
(See ICAO term AERODROME ELEVATION.)

AIRPORT LIGHTING- Various lighting aids that
may be installed on an airport. Types of airport
lighting include:
a. Approach Light System (ALS)- An airport
lighting facility which provides visual guidance to

Pilot/Controller Glossary

landing aircraft by radiating light beams in a
directional pattern by which the pilot aligns the
aircraft with the extended centerline of the runway on
his/her final approach for landing. CondenserDischarge Sequential Flashing Lights/Sequenced
Flashing Lights may be installed in conjunction with
the ALS at some airports. Types of Approach Light
Systems are:
1. ALSF-1- Approach Light System with
Sequenced Flashing Lights in ILS Cat-I configuration.
2. ALSF-2- Approach Light System with
Sequenced Flashing Lights in ILS Cat-II configuration. The ALSF-2 may operate as an SSALR when
weather conditions permit.
3. SSALF- Simplified Short Approach Light
System with Sequenced Flashing Lights.
4. SSALR- Simplified Short Approach Light
System with Runway Alignment Indicator Lights.
5. MALSF- Medium Intensity Approach Light
System with Sequenced Flashing Lights.
6. MALSR- Medium Intensity Approach Light
System with Runway Alignment Indicator Lights.
7. RLLS- Runway Lead-in Light System
Consists of one or more series of flashing lights
installed at or near ground level that provides positive
visual guidance along an approach path, either
curving or straight, where special problems exist with
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 Lighting 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