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6/17/21 

AIM 

technology. The New Generation RVRs were 
deployed in November 1994 and use forward scatter 
technology. The New Generation RVRs are currently 
being deployed in the NAS to replace the existing 
Taskers. 

a. 

RVR values are measured by transmissometers 

mounted on 14

foot towers along the runway. A full 

RVR system consists of: 

1. 

Transmissometer projector and related items. 

2. 

Transmissometer receiver (detector) and 

related items. 

3. 

Analog 

4.

 recorder. 

5. 

Signal data converter and related items. 

6. 

Remote digital or remote display program-

mer. 

b. 

The transmissometer projector and receiver are 

mounted on towers 250 feet apart. A known intensity 
of light is emitted from the projector and is measured 
by the receiver. Any obscuring matter such as rain, 
snow, dust, fog, haze or smoke reduces the light 
intensity arriving at the receiver. The resultant 
intensity measurement is then converted to an RVR 
value by the signal data converter. These values are 
displayed by readout equipment in the associated air 
traffic facility and updated approximately once every 
minute for controller issuance to pilots. 

c. 

The signal data converter receives information 

on the high intensity runway edge light setting in use 
(step 3, 4, or 5); transmission values from the 
transmissometer and the sensing of day or night 
conditions. From the three data sources, the system 
will compute appropriate RVR values. 

d. 

An RVR transmissometer established on a 

250 foot baseline provides digital readouts to a 
minimum of 600 feet, which are displayed in 200 foot 
increments to 3,000 feet and in 500 foot increments 
from 3,000 feet to a maximum value of 6,000 feet. 

e. 

RVR values for Category IIIa operations extend 

down to 700 feet RVR; however, only 600 and 
800 feet are reportable RVR increments. The 
800 RVR reportable value covers a range of 701 feet 
to 900 feet and is therefore a valid minimum 
indication of Category IIIa operations. 

f. 

Approach categories with the corresponding 

minimum RVR values. (See TBL 7

1

5.) 

TBL 7

1

Approach Category/Minimum RVR Table 

Category 

Visibility (RVR) 

Nonprecision 

2,400 feet 

Category I 

1,800 feet* 

Category II 

1,000 feet 

Category IIIa 

700 feet 

Category IIIb 

150 feet 

Category IIIc 

0 feet 

* 1,400 feet with special equipment and authorization 

g. 

Ten minute maximum and minimum RVR 

values for the designated RVR runway are reported in 
the body of the aviation weather report when the 
prevailing visibility is less than one mile and/or the 
RVR is 6,000 feet or less. ATCTs report RVR when 
the prevailing visibility is 1 mile or less and/or the 
RVR is 6,000 feet or less. 

h. 

Details on the requirements for the operational 

use of RVR are contained in FAA AC 97

1, Runway 

Visual Range (RVR). Pilots are responsible for 
compliance with minimums prescribed for their class 
of operations in the appropriate CFRs and/or 
operations specifications. 

i. 

RVR values are also measured by forward 

scatter meters mounted on 14

foot frangible 

fiberglass poles. A full RVR system consists of: 

1. 

Forward scatter meter with a transmitter, 

receiver and associated items. 

2. 

A runway light intensity monitor (RLIM). 

3. 

An ambient light sensor (ALS). 

4. 

A data processor unit (DPU). 

5. 

Controller display (CD). 

j. 

The forward scatter meter is mounted on a 

14

foot frangible pole. Infrared light is emitted from 

the transmitter and received by the receiver. Any 
obscuring matter such as rain, snow, dust, fog, haze 
or smoke increases the amount of scattered light 
reaching the receiver. The resulting measurement 
along with inputs from the runway light intensity 
monitor and the ambient light sensor are forwarded to 
the DPU which calculates the proper RVR value. The 
RVR values are displayed locally and remotely on 
controller displays. 

Meteorology 

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