The IM159 is a precision-built handheld anemometer made from non-ferrous metal. Wind speed readings are shown on an analogue scale calibrated in knots, metres per second or miles per hour. We use a wind tunnel to calibrate the device and can issue a certificate of conformity.
The IM159 is a mechanical instrument and requires no battery or form of electricity. It is manufactured to British Meteorological Office specifications (ref. 23510) and is ideally suited for use as a contingency device in case automated sensors become unavailable. Its primary application is on offshore helidecks (see CAP 437: Standards for Offshore Helicopter Landing Areas).
It is advised that the IM159 is serviced annually to ensure it continues to function optimally and provide accurate readings.