Visibility Sensor FS11

Features

• Unique window contamination

correction

• Accurate and traceable forward

scattering measurement

• Technical design and high-power

heating according to FAA

guidelines

• Frangible composite fiber mast

• Can be upgraded for sensing

present weather

Benefits

• The most widely proven forward

scatter RVR sensor

• Visibility sensor selected and used

by FAA

• Meets FAA and ICAO

specifications

• Accurate and traceable

measurement

• Can be used for both aeronautical

and synoptical applications

• Minimal maintenance needs

• Meets ICAO frangibility standards

The main applications of FS11 are runway

visual range (RVR) and synoptical and

aeronautical visibility measurements.

FS11 is also well suited for other

demanding applications, such as

visibility measurement at ports and

harbors.

Scientifically Valid Chain of

Calibration

FS11 is calibrated through a scientifically

valid chain of reference. The scattering

response of the calibration device can be

clearly traced to a reference FS11 visibility

sensor, which is in continuous operation

at Vaisala outdoor test field along with

reference transmissometers and other

instrumentation. The visibility

measurement of FS11 is also traceable to

FAA reference sensors.

Low Maintenance Need

FS11 incorporates a technique that

measures and compensates for window

contamination. It ensures unparalleled

measurement accuracy between window

cleanings. It also enables much longer

window cleaning intervals than

compared to conventional visibility

sensors.

The unique system works by monitoring

the total reflectance of the window

surface. It automatically compensates for

visibility measurement errors caused by

window contamination.

The sophisticated self-diagnostics and

modular design allow for very short

service times. The measurement fork and

optional background luminance sensor

LM21 are independent instruments that

can be replaced quickly as pre-calibrated

spare parts.

Reliable Operation in

the Harshest Weather

Four main design features are combined

in FS11 to ensure reliable operation in

the harshest weather. The first is

the window contamination

compensation technique. The second is

the “head-down” design of the optical

heads, which protects them against

virtually all windblown particles (even

those flying horizontally).

High-power heaters are the third feature.

Each heater has its own temperature

monitoring and control mechanism to

prevent snow accumulation during

the heaviest snowstorm.

As a final measure, there is an optical

path clearance monitoring circuitry to

verify that measurement is not affected

by obstructions.

Visibility Sensor FS11 is intended for the most

demanding weather applications, such as runway visual

range (RVR), aeronautical and synoptical visibility. It

provides the optimal combination of the best accuracy,

the highest reliability, broad measurement range, and

low maintenance need.