Why you should be talking in altitude when your drone is telling you something else
Civil Aviation Safety Authority drone regulations specify a drone can only be flown 400ft above ground level without further approval. Air band radio is the perfect tool, sometimes mandatory, to keep situationally aware of other air traffic in the vicinity. Does being a responsible drone pilot and flying per the rules keep drone pilots out of trouble?
A flight has been requested from a local golf course. The elevation of the terrain is 79ft. With due diligence, the flight is flown at 400ft above ground level. As required a radio call is made detailing the drone is 400ft Above Ground Level (AGL). A nearby aircraft has called at 500ft (ignoring the small elevation). Both crews assume 100ft separation, the aircraft pass with 21ft (7 metres) separation
Small drones typically take a sample of the air pressure when the aircraft first initialises. This is then ground zero. Height is now measured above this point and displayed for the pilot to use. A drone can be flown at a negative height reading due to this. This information is of no significant use to describe the position in the real world.
Drone regulations in Australia stipulate the aircraft will not be flown above 400ft AGL (Above Ground Height). This information is not directly available from the drone, interpretation of aviation charts is required to ensure operations remain within Civil Aviation Safety Regulations drone regulations. A flight flown off the top of a mountain must follow the terrain down.
Piloted aircraft and larger Remotely Piloted Aircraft Systems operate on altitude. Altitude is the height above mean sea level, or height above the sea level pressure of the day. Seldom are pilots calculating the exact height above the ground. To calculate the altitude of the operation, find the elevation and add the height above the ground. Drone regulations alone do not requirethe calculation of altitude.
Know the definition, the datum and the difference
Knowing the difference between drone height, height above the ground (AGL) and altitude seems so inconsequential, particularly when drone manufactures confuse meanings so often. Drones and drone pilots are part of the airspace system. Speaking in the same terms as other airspace users is essential for separation and integration. Simply describing the height above the take off point or height above the ground isn’t good enough. A three-dimensional position must be described concisely to a person moving 8 kilometres per minute or 133 metres every second.