Are crashes a thing of the past? While obstacle avoidance should reduce the likely-hood of piling your aircraft into the ground, there are many scenarios where these safety measures will fall short. When in doubt, consult the manual included with your aircraft or at least watch some crashes on YouTube for your model. While this post doesn’t address every possible scenario, I do hope to outline the majority of reasons you should be on the alert even when flying an aircraft with avoidance.
Small obstacles
Tree branches and twigs are a nightmare for avoidance systems. Their round shape and small cross section are practically invisible to sonar. Forward facing avoidance cameras are unlikely to lock on, especially if they enter the field of view suddenly or from slightly off center.
When it’s off ( No kidding )
Sounds crazy but yes, people often will disable the avoidance because they’re intentionally trying to fly through or near something on purpose. A good example of this would be when you’re trying to get a close look at the roof of your house or want to fly past an object of interest to jazz up your next video clip. Often avoidance will ruin these shots, causing your aircraft to stop suddenly when you don’t want it to. Pilots in these scenarios will disable avoidance and forget it’s off.
Indoors
Avoidance systems rely on an array of sensors with different capabilities. Low light or low contrast surfaces have posed issues in the past and will continue to in the future. Avoid surfaces that are glossy, all one color or places poorly lit.
High Speeds
Depending on your model, flights at high speed can render avoidance useless.
Over Water
Water is especially good at confusing downward facing cameras and sonar, especially if there are waves.
Backlit shots
All cameras must have good exposure to work well. While sunsets are glorious, the glare can defeat even the most robust systems currently available.
Pilot Error
The biggest problem with avoidance systems is that pilots get a false sense of security. Assuming a crash is impossible causes many pilots to fly without fear. Even worse, some pilots will make it game to fly towards objects or people to demonstrate the avoidance capabilities. Always consider these avoidance systems to be emergency backups to safe piloting practices.