GVC Meteorology for Commercial UAS — Questions and Answers
Question 1: What is the primary weather hazard that limits most small UAS operations?
- Fog
- High wind speeds exceeding the UAS performance envelope (Correct answer)
- High temperatures
- Low humidity
Correct answer: High wind speeds exceeding the UAS performance envelope
High wind speeds are the most common weather-related limitation for small UAS operations. If wind speed exceeds the drone's maximum rated airspeed, it cannot maintain position or return to the pilot. Gusts can cause loss of control, and sustained winds increase battery consumption and reduce flight time.
Question 2: What does a METAR report provide to a UAS remote pilot?
- A 7-day weather forecast for the region
- A routine aeronautical weather observation at a specific aerodrome at a specific time (Correct answer)
- Satellite imagery of cloud formations
- Real-time wind data from the operating site
Correct answer: A routine aeronautical weather observation at a specific aerodrome at a specific time
A METAR (Meteorological Aerodrome Report) is a standardised weather observation from a specific aerodrome, issued at regular intervals (typically every 30 minutes or hourly). It provides data on wind direction and speed, visibility, cloud cover, temperature, dew point, and pressure — all useful for UAS flight planning.
Question 3: How does air temperature affect UAS battery performance?
- Higher temperatures always improve battery life
- Cold temperatures reduce battery capacity and can cause voltage drops, reducing flight time (Correct answer)
- Temperature has no effect on modern lithium polymer batteries
- Only temperatures above 40°C affect batteries
Correct answer: Cold temperatures reduce battery capacity and can cause voltage drops, reducing flight time
Cold temperatures significantly reduce the chemical reaction rate in lithium polymer (LiPo) batteries, lowering their available capacity and increasing internal resistance. This can cause unexpected voltage drops under load, reduce flight time, and in extreme cold, cause the battery to cut out entirely. Pilots must factor in reduced flight times during cold weather operations.
Question 4: What is 'wind shear' and why is it hazardous to UAS operations?
- A gradual change in wind speed over 24 hours
- A sudden change in wind speed or direction over a short distance, which can cause loss of control (Correct answer)
- The effect of wind on camera stabilisation only
- A type of wind that only occurs at night
Correct answer: A sudden change in wind speed or direction over a short distance, which can cause loss of control
Wind shear is a sudden change in wind speed, direction, or both over a short distance (either vertically or horizontally). For UAS, wind shear can cause sudden uncommanded changes in altitude or position, potentially leading to loss of control, collision with obstacles, or departure from the operational volume. It commonly occurs near buildings, terrain features, and during thunderstorm activity.
Question 5: What weather information does a TAF provide, and how does it differ from a METAR?
- A TAF is a historical weather log; a METAR is a forecast
- A TAF is an aerodrome weather forecast valid for a future period; a METAR is an observation of current conditions (Correct answer)
- A TAF covers a 30-day period; a METAR covers 24 hours
- There is no difference; they are the same report
Correct answer: A TAF is an aerodrome weather forecast valid for a future period; a METAR is an observation of current conditions
A TAF (Terminal Aerodrome Forecast) is a forecast of expected weather conditions at an aerodrome, typically valid for 9 to 30 hours. A METAR is an observation of actual current conditions. Both are essential for UAS flight planning: the TAF for planning ahead, and the METAR for confirming conditions on the day.
Question 6: How does precipitation (rain) affect UAS operations?
- Rain has no effect on modern commercial drones
- Rain can damage electronics, reduce visibility, affect sensors, and degrade GNSS accuracy (Correct answer)
- Rain only affects operations above 100 metres
- Rain improves the drone's cooling system and extends flight time
Correct answer: Rain can damage electronics, reduce visibility, affect sensors, and degrade GNSS accuracy
Rain poses multiple hazards to UAS operations: water ingress can damage electronics and motors, rain reduces visibility for both the pilot and onboard cameras, water droplets on optical sensors degrade their performance, and heavy rain can attenuate GNSS signals. Most commercial UAS are not rated for operation in rain unless specifically IP-rated.
GVC Meteorology for Commercial UAS
What is the primary weather hazard that limits most small UAS operations?