Measurement
Response Time | Units | Operational Range | Resolution | Accuracy
(+/-) | Specification Range |
Wind Speed
1 second | m/s | 0.4 to 60.0 m/s | 0.1 | Larger of 3% of reading or least significant digit | 0.4 to 40.0 m/s |
| ft/min | 59 to 11,948 ft/min | 1 | 59 to 7877 ft/min |
| km/h | 1.0 to 218.0 km/h | 0.1 | 1.0 to 144.0 km/h |
| mph | 0.8 to 135.0 mph | 1 | 0.8 to 89.0 mph |
| knots | 0.6 to 118.3 kt | 0.1 | 0.6 to 78.0 kt |
| Beaufort | 0 to 12 B | 0.1 | 0 to 12 B |
| 1 inch diameter impeller with precision axle and sapphire bearings. Off-axis accuracy -1% @ 5º off-axis; -2% @ 10º; -3% @ 15º. Calibration drift < 1% after 100 hours use at 16 MPH / 7 m/s. Sustained operation above 60 MPH / 27 m/s will wear impeller rapidly and may cause destruction of impeller. Replacement impeller (NK PN-0801) may be field-installed without tools (US Patent 5,783,753). |
Wind Direction / Forward Heading
1 second | ° | 360° | 1 | 5° | 0 to 360° |
| Cardinal Points | 360° | 16 Points | 5° | 0 to 360° |
| 2-axis solid-state magnetoresistive sensor mounted perpendicular to unit plane to permit operation while measuring wind speed. Declination/variation adjustable for True North readout. Accuracy of measurements dependent upon unit's vertical position. Self-calibration routine eliminates magnetic error from batteries or unit and must be run after every full power-down (battery removal or change). |
Temperature
1 second | °F | -49.0 to 257.0 °F | 0.1 | 1.8 °F | -20.0 to 158.0 °F |
| °C | -45.0 to 125.0 °C | 0.1 | 1.0 °C | -29.0 to 70.0 °C |
| Measures air, water and snow temperature. Thermally isolated, hermetically sealed, precision thermistor mounted externally (US Patent 5,939,645). Calibration drift negligible. |
Relative Humidity
1 minute | %RH | 0.0 to 100.0 % | 0.1 | 3.0 %RH | 5.0 to 95.0 % non-condensing |
| Polymer capacitive humidity sensor mounted in thin-walled chamber external to case for rapid, accurate response (US Patent 6,257,074). (To achieve stated relative humidity accuracy, unit must be permitted to equilibrate to external temperature when exposed to large, rapid temperature changes and must be kept out of direct sunlight.) Calibration drift +/- 2% over 24 months. Relative humidity may be recalibrated at factory or in field using Kestrel Humidity Calibration Kit (NK PN-0802). |
Pressure
1 second
(mb & PSI 4000 model only) | inHg | 8.86 to 32.48 inHg | 0.01 | 0.05 inHg | At 77.0 °F, <19,700 ft |
| hPa / mb | 300.0 to 1100.0 hPa / mb | 0.1 | 1.5 hPa / mb | At 25.0 °C, <6,000 m |
| PSI | 4.4 to 16.0 PSI | 0.1 | 0.1 PSI | At 77.0 °F, <19,700 ft |
| Monolithic silicon piezoresistive pressure sensor with second-order temperature correction. Maximum error beyond specified temperature, +/- 0.09 inHg / 3.0 hPa. Calibration drift typically -0.03 inHg / -1.0 hPa per year. Pressure sensor may be recalibrated at factory or in field. |
Altitude
1 second | ft | -6000 to 30000 ft | 1 | 50 ft | At 77.0 °F, <19,700 ft. Max error +/- 98 ft |
| m | -2000 to 9000 m | 1 | 15 m | At 25.0 °C, <6,000 m. Max error +/- 30 m |
| Temperature compensated pressure (barometric) altimeter. |
Crosswind
Headwind, Tailwind
1 second | mph | 0.8 to 135.0 mph | 1 | 5% | 8.5 to 89.0 mph |
| ft/min | 59 to 11,880 ft/min | 1 | 5% | 750 to 7832 ft/min |
| km/h | 1.0 to 217.3 km/h | 0.1 | 5% | 13.7 to 143.2 km/h |
| m/s | 0.4 to 60.0 m/s | 0.1 | 5% | 3.8 to 40.0 m/s |
| knots | 0.6 to 117.3 kt | 0.1 | 5% | 7.4 to 77.0 kt |
| Calculated from the primary measurements of wind speed, wind direction and target heading. Auto-switching headwind/tailwind indication. Ranges expressed refer to primarywind speed. |
Wind Chill
1 second | °F | 0.7 to 135.0 MPH, -49.0 to 257.0 °F | 0.1 | 1.8 °F | 1.8 to 89.0 mph, -50.0 to 50.0 °F |
| °C | 0.4 to 60.0 m/s, -45.0 to 125.0 °C | 0.1 | 1.0 °C | 0.4 to 40 m/s, -45.6 to 10.0 °C |
| Calculated from the primary measurements of wind speed and temperature. Utilizes the NWS Wind Chill Temperature (WCT) Index, revised 2001, with wind speed adjusted by a factor of 1.5 to yield equivalent results to wind speed measured at 10 m above ground. (Specification temperature limits established by WCT Tables.) |
Heat Index
1 minute | °F | 0.0 to 100.0 %RH, -49.0 to 257.0 °F | 0.1 | 3.6 °F | 70.0 to 130.0 °F, 0 to 100% RH |
| °C | 0.0 to 100.0 %RH, -45.0 to 125.0 °C | 0.1 | 2.0 °C | 21.1 to 54.4 °C, 0 to 100 %RH |
| Calculated from the primary measurements of temperature and relative humidity. Utilizes the NWS Heat Index (HI) tables. (Specification temperature limits established by HI tables.) |
Dewpoint
1 minute | °F | 0.0 to 100.0 %RH, -49.0 to 257.0 °F | 0.1 | 3.6 °F | -20.0 to 158.0 °F, 20.0 to 95.0% RH |
| °C | 0.0 to 100.0 %RH, -45.0 to 125.0 °C | 0.1 | 2.0 °C | -29.0 to 70.0 °C, 20.0 to 95.0 %RH |
| Calculated from the primary measurements of temperature and relative humidity. Temperature to which the air would need to be cooled at a constant pressure to become saturated. |
Wet Bulb Temperature
1 minute | °F | -49.0 to 257.0 °F, 0.0 to 100.0 %RH, 8.86 to 32.48 inHg | 0.1 | 3.6 °F | 32.0 to 100.0 °F, 5.0 to 95.0% RH, 8.86 to 32.48 inHg, <19700 ft |
| °C | -45.0 to 125.0 °C, 0.0 to 100.0 %RH, 300.0 to 1100.0 hPa | 0.1 | 2.0 °C | 0.0 to 37.8 °C, 5.0 to 95.0 %RH, -2000.0 to 9000.0 hPa, <6000 m |
| Calculated from the primary measurements of temperature, relative humidity and pressure. Temperature indicated by a wet bulb psychrometer. |
Density Altitude
1 second | ft | -49.0 to 257.0 °F, 0.0 to 100.0 % RH, 8.86 to 32.48 inHg | 1 | 246 | 32.0 to 100.0 °F, 5.0 to 95.0 %RH, 8.86 to 32.48 inHg, <19700 ft |
| m | -45.0 to 125.0 °C, 0.0 to 100.0 %RH, 300.0 to 1100.0 hPa | 1 | 75 | 0.0 - 37.8 °C, 5.0 to 95.0 %RH, -2000 to 9000 hPa, <6000 m |
| Calculated from the primary measurements of temperature, relative humidity and pressure. Air density converted to equivalent sea level elevation at the International Standard Atmosphere. |
Max/Avg Wind Speed (Air Velocity),
Crosswind, Headwind/Tailwind | One-button clear and restart of Max Wind Gust and Average Wind measurement. |
| Data Storage / Display | Minimum, maximum, average and logged history stored and displayed for every measured value. 1400-point data logger with graphical display. Auto data storage; interval settable from 2 seconds to 12 hours. Manual data capture. |
| Data Upload | Requires optional PC interface (NK PN-0830) and provided software. RS-232 connection with USB adapter available. |
| Display | Multifunction, multi-digit programmable dot-matrix display. |
| Display Update | 1 second. |
| Display Backlight | Choice of aviation green or visible red electroluminescent backlight. Automatic or manual activation. |
| Clock / Calendar | Real-time hours:minutes:seconds clock, calendar, automatic leap-year adjustment. |
Operational Temperature Range
(LCD and Batteries) | The operational temperature range of the liquid crystal display and batteries is 14° F to 131° F / -10 °C to 55 °C. Beyond the limits of the operational temperature range, the unit must be maintained within range and exposed for minimum time necessary to take reading. |
| Storage Temperature | -22 °F to 140 °F / -30 °C to 60 °C. |
| Auto Shutdown | User-selectable: 15 or 60 minutes with no key presses or disabled. |
| Languages | English, French, German, Italian, Spanish. |
| Certifications | CE certified. Individually tested to NIST-traceable standards (written certificate of tests available at additional charge). |
| Batteries | AAA Alkaline, two, included. Average life, 400 hours of use, +/-depending on backlight use. |
| Environmental | Waterproof (IP67 standard). Drop-tested (MIL.STD.810F; unit only. Substantial impact may damage replaceable impeller.). |
| Dimensions | Unit 5.0 x 1.8 x 1.1 in / 12.7 x 4.5 x 2.8 cm. |
| Weight | Unit 3.6 oz / 102 g. |
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| Kestrel Meters are designed and manufactured at NK’s facility in Boothwyn, Pennsylvania, and are individually calibrated at the time of manufacture. Every Kestrel Meter comes with a Certificate of Conformity to document the unit’s accuracy—all Kestrel measurements are traceable to the National Institute of Standards and Technology, ensuring the highest level of reliability. |
