Drone operations differ widely with commercial airline operations in nature, purpose, and duration. Thereby, there are completely different sets of airspace rules that safeguard UAV operations. Drones fly much closer to the surface and thus drone operators must be aware of the restricted and unrestricted airspace around them. Understanding the airspace drones are allowed to operate in can prove to be greatly beneficial. The Federal Aviation Administration (FAA) has devised 4 basic airspace categories for American drones. Most countries all over the world follow a similar categorization with adaptability changes.

UAV Airspace

Airspace for drones can be majorly divided into four categories:

1. Controlled Airspace

Controlled Airspace is an area that is monitored and controlled by Air Traffic Control (ACT) or UAV Traffic Management (UTM) services. In this airspace, the vertical and lateral boundaries are preset and any UAV is not permitted to breach those boundaries. Such types of parameters are often referred to as Geofencing, which is a standard feature in most drones. The classes which belong in controlled airspace are: Class A, B, C, D & E. For instance, a drone operator in China would require permission from the CAAC to fly in controlled areas, etc.

2. Uncontrolled Airspace

This airspace is where most drones fly. It is also referred to as the Class G airspace. Air traffic is not controlled by the aviation authorities in this particular airspace. The altitude cap can be anywhere from 700ft to 1200ft depending upon the surface level. The altitude limit may also change from country to country. Also, this airspace is the least restrictive airspace. However, the FAA states that, although the airspace is uncontrolled it is not unregulated. Therefore all aviation rules still apply to this airspace. Drone pilots are often advised to not carry unregulated drone operations in uncontrolled airspace.

3. Special Use Airspace

Special Use Airspace (SUA) is globally recognized as the restricted and highly controlled airspace of all. Drone and aircraft pilots alike require special permission to operate in this airspace category. This airspace includes:

  • Prohibited areas- here all flights are terminated due to national security reasons.
  • Restricted areas- here airspace operations are deemed hazardous or in military use.
  • Military operation areas- this area is reserved especially for military training activities.
  • Alert areas- drone and flight pilots are cautioned in these areas due to any unusual aerial activities.

SUA is identified differently in different countries.

4. Other Airspace

Additional airspace which may endanger the security of other persons or property is highly prohibited. For example, drones are not permitted to fly over densely populated areas like sporting events, crowded streets, etc. UAVs are also restricted to fly in the nearby vicinity of an airport or a helipad.

Understanding airspace
Understanding UAV Airspace

Larger drones like military, passenger, cargo and all aircraft rely on aeronautical charts to traverse any airspace. An aeronautical chart provides the pilot with important telemetry and surrounding data. An aerial chart is necessary for a safe and regulated flight.

Types of Aeronautical Charts

There are mainly two types of charts which are widely used today:

1.Sectional Charts

A sectional chart shows the terrain elevation, ground features that are identifiable from an altitude, navigation routes, classes, latitudes, longitudes, and other important features. A sectional chart mainly used when an aircraft is operating under visual flight rules (VFR). VFR is a set of regulations that the pilot operates in when the weather conditions are clear. Sectional charts are scaled at 1:500,000.

2. Terminal Charts

VFR terminal charts just like their sectional counterparts are used when an aircraft is operating under VFR. Terminal charts depict similar topographical features as sectional charts. Terminal charts are primarily used in a Class B airspace. However, a terminal chart is more detailed than a sectional chart and is scaled at 1:250,000. Terminal charts contain additional details about approach, departure, transitions, and procedures for Class B airspace around airports.

Understanding Airspace: An aeronautical chart.
(Image courtesy: AOPA)

How to read an aeronautical chart?

Aeronautical charts contain detailed information not only about the topography but also various procedures pilots must adhere to. With tons of symbols and signs, they can be confusing at first glance. However, pilots are trained to understand these charts with ease. There are legends and keys to each chart which the pilot memorizes. Each class of airspace is denoted with a colored circle. For instance, a blue-colored circle above a region indicates that it lies in a Class B airspace. Similarly, a magenta-colored circle indicates a class C airspace and so on. Even symbols which are colored differently denote different meanings. A blue-colored runway means that there is no control tower there. Even the radio frequencies are always given under an airport’s name, like CT-119.8. Pilots make use of these frequencies to establish contact with control towers. Read here for a more detailed note on deciphering these charts.