Autonomous Drone Flight 101

By Brandon Guillot, RPC, MAS

One of the most fascinating aspects of modern sUAS is the ability to conduct autonomous flights.

These flights are conducted in a way where the pilot has determined a specific course of action that would be executed by the aircraft — but is not manually providing the “stick and rudder” inputs to accomplish that objective.

Autonomous flights are extremely popular for many reasons, and they even point the way to the future. Once we see changes in the FAA regulatory environment, automatic flights will form the backbone of “Last Mile Delivery” systems using UAS to deliver goods to consumers.

Compliance with Part 107

It would be wise for drone pilots to become familiar with some of the elements of automatic flights, starting with the legal concerns from the FAA. Under FAR Part 107, autonomous flights are allowed as long as the flights fall within the restrictions of that regulation.

The aircraft must be operated within Visual Line of Sight (VLOS), not flown over people who are not involved in the operation, below 400 feet Above Ground Level unless you are over an obstacle, weather minimums are followed, and you are not operating in a careless or reckless manner.

Make sure these areas are in compliance as part of your preflight planning efforts, particularly when you know that autonomous flights are either planned or at least likely.

Categories of Autonomous Drone Flights

Once the regulatory questions are safely answered, the pilot needs to decide what kind of autonomous flight they need to conduct. These flights generally fit into the following categories:

1. Return to Home (RTH) or Return to Launch (RTL):

These tend to be the most common forms of automatic flight by sUAS pilots. In these situations, the aircraft will fly back to their starting point either on command by the pilot, or in the event of a lost-link incident. This system can be extremely useful, particularly if it prevents a fly-away situation. However, sUAS pilots should use caution for a few very important areas regarding RTH or RTL.

First, older generation aircraft did not have any form of collision avoidance software on board; they would fly in the shortest distance home, such as a straight line.

Many would climb to a “safer” altitude (such as around 90 feet AGL) to avoid striking most obstacles, but that was not a foolproof method of avoiding a collision. Even modern sensors may have a hard time avoiding tree branches or power lines.

The second concern is a human factor — complacency. There are two kinds of pilots: those who have had a GPS failure in flight, and those who will.

If you rely on an RTL switch most of the time to bring your aircraft home, you are setting yourself up for failure once you have an on-board problem where manual skills are the only thing to get your expensive flying machine back on the ground in one piece.

2. Point of Interest:

These settings rely on positioning the aircraft or its camera to follow a set point for the camera. They can be either fixed position (such as using a Circle mode to take photos of a house from all angles) or following a moving target.

Depending on the capabilities of the aircraft and its sensor equipment, you may have to position the aircraft to keep the camera directly pointed at the object in question, or the on-board computers may work together to coordinate both the aircraft and the sensor and maintain position.

The latter generally only occurs when you have a camera gimbal with 360-degree rotation capability. Systems that focus on a moving target typically rely on a secondary GPS sensor to provide something for the aircraft to follow. For example, on the Yuneec Typhoon H, it will either follow the GPS sensor in the Control System or the one located in the Wizard Wand that can be paired with the aircraft.

Once again, caution should be used in both situations. Upon reaching your target altitude, conduct a 360-degree yaw turn to make sure you are not going to strike any errant structures or tree limbs. Even more caution should be used if you will be following a moving sensor target since there will be the potential for obstacles throughout the course of the flight.

3. Automatic Waypoints:

These flights rely on setting electronic waypoints either in the air or on the ground then sending the aircraft to fly to each one in turn. This particular flight is fairly complicated, and we will discuss it specifically during the next article.

As always, make sure that safe decisions are being made when planning out any autonomous flights. In addition to the regulatory compliance questions under Part 107, take a few minutes to run the flight through your Hazard Vulnerability Analysis and determine any weak areas.

Do you need to increase your altitude?

Do you need to wait until the winds are calmer?

Do you need to scrub the flight completely until a safer time?

All of these decisions and more will play a factor in the both the safe and effective use of your aircraft.

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