Present Weather Sensor FS11P

Vaisala Present Weather Sensor FS11P is intended for the most demanding weather applications such as runway visual range (RVR), aeronautical and synoptical visibility, and present weather observation. It provides the optimal combination of the best accuracy, the highest reliability, broad measurement range, and low maintenance need.

Benefits

• Excellent value: RVR, visibility, and present weather all-in-one
• The most widely proven forward scatter RVR sensor
• Visibility sensor selected and used by FAA
• Meets FAA and ICAO specifications
• Can be used for both aeronautical and synoptical applications
• Minimal maintenance needs
• Compatible with FD12P
• Meets ICAO frangibility standards

Scientifically Valid Chain of Calibration

FS11P is calibrated through a scientifically valid chain of reference. The scattering response of the calibration device can be clearly traced to a reference FS11P visibility sensor, which is in continuous operation at Vaisala outdoor test field along with reference transmissometers and other instrumentation. The visibility measurement of FS11P is also traceable to FAA reference sensors.

Low Maintenance Need

FS11P 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 visibility measurement fork, present weather detector, and  optional background luminance meter 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 FS11P 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

Technical Compatibility

In addition to the technological similarity, FS11P is compatible with, and can be used to replace, FD12P. They both provide the same mechanical, electrical and communication interfaces, and they transmit similar message formats widely used in aviation and meteorology.