Angry Birds That Attack Aerial Drones

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Falcon attacking a Mavic 2

Falcon Attacking a Mavic 2

Birds of prey are fascinating to watch until they set their sights on your aerial drone. Attacks on drones have been widely reported but probably haven’t been a concern to you, as a drone pilot, unless you’ve fallen victim to one.

We recently had our own bad experience with a bird taking down our drone while we were on a commercial photo shoot. We were taking photos using autopilot, where the drone stopped, took a picture, and then continued to its next position. Apparently, a bird took offense at our slow-moving drone and attacked. Fortunately, the 200-ft fall was broken by vegetation! After replacing a broken propeller, we were able to continue our job.

Why Would a Bird Attack a Small Aerial Drone?

Three reasons come to mind:

  1. They feel threatened by the drone’s intrusion into their territory.
  2. They think the drone might be a source of food.
  3. They feel their nest is threatened. Be especially careful during mating and nesting season.

Large birds of prey, such as eagles and hawks, can be hazardous to your drone especially if they’re much larger. I can’t imagine an attack that’s not hazardous to the bird as they have the spinning propellers to avoid. But if they manage to latch onto your drone’s vulnerable underbody, its next stop is going to be on the ground.

This article on bird attacks at the COPTRZ web site provides additional detail.

Avoid Bird Attacks!

We didn’t have a problem with bird attacks until we automated our photo runs, which stop for several seconds to snap each picture. Taking your photos at lower altitudes will present your drone as a threat and an ideal target. However, photography at 250 feet or higher is less threatening and takes away a lot of their advantage. High-resolution photos can be cropped to simulate a zoom-in effect without sacrificing very much picture quality.

Flying significantly faster than most birds (and prey) will also present your drone as a more challenging target. All of our video runs are done on autopilot with altitudes above 200 feet and speeds above 20 mph.

Aerial mapping has its risks as well, but our mapping runs are almost always at 400 feet altitude and speeds above 15 mph. We program our drones to take pictures while maintaining cruise speed because the risk of blur is so low. Most birds at that altitude aren’t going to pay your drone much attention.

Documenting Bird Attacks

Several interesting bird attack videos are posted to this site, Dronelife. The threat is real!

We’re now enabling video in our photo runs, between the photos, to possibly capture our own adventures with angry birds. Should our drone be recovered, at least we’ll have some consolation along with evidence that can be presented with our insurance company claim.

Flying over People and Flying at Night

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Soccer

Flying Over People

The FAA published its final rule on April 21, 2021 regarding aerial drones flying over people and flying at night. It’s posted to the FAA’s website at:  Operations Over People General Overview.

This blog summarizes their new rule, but there are significant details left out for brevity. If you intend to fly over people or at night, then you’ll want to read the details. In addition, the FAA has published further details in their Circular 107-2A.

FAA’s Summary of their New Rule

Cited directly from the FAA, “This rule amends part 107 by permitting routine operations of small unmanned aircraft over people, moving vehicles, and at night under certain conditions. It also changes the recurrent training framework, expands the list of persons who may request the presentation of a remote pilot certificate, and makes other minor changes.”

Mike’s take on Aerial Drone Operations over People

The FAA established four categories of drone operations over people. Category 1 has the lowest requirements through Category 4, which has the strictest requirements.

Category 1 aerial drones must weigh 0.55 lbs or less and are permitted to transit over people as long as rotating parts are covered so as to prevent lacerations (read propeller guards).  However, sustained flight over people is not allowed. Only a one-time transit over an assembled gathering is permitted.

Category 2 aerial drones must meet the requirements of Part 107.120 and be listed on an FAA-accepted Declaration of Compliance. However, sustained flight over people is not allowed. Only a one-time transit over an assembled gathering is permitted. Rotating parts must be covered so as to prevent lacerations.

Section 120 (which is new) states the aerial drone “Will not cause injury to a human being that is equivalent to or greater than the severity of injury caused by a transfer of 11 foot-pounds of kinetic energy upon impact from a rigid object.” (See example below.)

Category 3 aerial drones must meet the requirements of Part 107.130 and be listed on an FAA-accepted Declaration of Compliance. However, sustained flight over people is not allowed. Only a one-time transit over an assembled gathering is permitted, but exposure levels are a little more relaxed than Category 2. Operations over a restricted-access gathering of people is permitted as long as everyone has been notified that a small aerial drone may be flying over them. Rotating parts must be covered so as to prevent lacerations.

Section 130 (which is new) states the aerial drone “Will not cause injury to a human being that is equivalent to or greater than the severity of injury caused by a transfer of 25 foot-pounds of kinetic energy upon impact from a rigid object.” (See example below.)

Category 4 aerial drones and operators must meet a higher degree of certification. The FAA states “Eligible Category 4 small unmanned aircraft must have an airworthiness certificate issued by the FAA under Part 21 and must be operated in accordance with the operating limitations specified in the FAA-approved Flight Manual or as otherwise specified by the Administrator. The airworthiness certificate allows small unmanned aircraft operations for compensation and hire.” The requirements are a good read and recommended for pilots who wish to qualify for Category 4 operations.

How does the FAA calculate Kinetic Energy?

The FAA’s Circular 107-2A page 8-15 provides this formula for calculating the kinetic energy in foot-pounds:

KE = 0.0155 x drone weight (in lbs) x (velocity in mph)²

For example, a DJI Mavic 2 drone weighs about 2 lbs and its terminal velocity is about 45 mph. (Source: MavicPilots forum.) Using these numbers, the KE of a Mavic 2 in terminal velocity (free fall) is calculated to be 63 ft-lbs. Therefore, velocity would have to be reduced to less than 19 mph to comply with Category 2 operations – that is 11 foot-pounds. This number means that you will have to fly low and slow.

Night Operations

This new rule also allows routine operations of small aerial drones at night under two conditions:

  1. The remote pilot in command must complete an updated initial knowledge test or online recurrent training.
  2. The aerial drone must have lighted anti-collision lighting visible for at least three (3) statute miles that has a flash rate sufficient to avoid a collision.