Can You Fly a Drone in Fog?

Many of us have seen them: beautiful pictures and videos that have been taken above a layer of fog, adding a dreamy and ethereal look to local landscapes.

There are some who specifically fly during fog to capture such images, while there are countless others that, without planning, capture foggy photos and videos when the weather seemingly instantly and unexpectantly changes, like here in Florida.

In either scenario, you’re left wondering – can drones fly in fog?

While many, if not most drones can physically fly in the fog, caution is suggested when flying in any type of precipitation, which includes fog, rain, snow, clouds, or mist. Precipitation can and does harm the internals of many unprotected drones.

If you’re a Part 107 operator flying in the United States, the FAA has additional concerns and mandates when it comes to flying in fog.

Rules, laws, and mandates derived from flying through cloud cover are worth brushing up on, so keep reading!

The FAA’s rules for flying in the fog #

If you’re a Certified Part 107 drone operator, flying in the fog is something the FAA has concerns about, as we touched on in the intro.

While we here at Droneblog do not offer legal advice, below are two specific areas that drone operators should consider, purely from the FAA’s standpoint, when considering flying in foggy conditions.

The old adage applies: Just because you can do something, should you?

VLOS (visual line of sight) #

Flying within visual line of sight has been a very hot topic as of late, whether Part 107-certified or simply a hobbyist.

One thing we as drone operators might not realize is that if flying in very heavy fog, the visibility of the drone is hampered. Perhaps only a little in light fog, and maybe almost completely in dense fog.

In regard to visual line of sight (VLOS), something all drone operators must follow, below is a quoted excerpt from the FAA rules governing Part 107, to consider:

(a) With vision that is unaided by any device other than corrective lenses, the remote pilot in command, the visual observer (if one is used), and the person manipulating the flight control of the small unmanned aircraft system must be able to see the unmanned aircraft throughout the entire flight in order to:

(1) Know the unmanned aircraft’s location;

(2) Determine the unmanned aircraft’s attitude, altitude, and direction of flight;

(3) Observe the airspace for other air traffic or hazards; and

(4) Determine that the unmanned aircraft does not endanger the life or property of another.
§ 107.31 Visual line of sight aircraft operation.

If we were to go by just this particular section of Part 107.31, then it would be safe to say that if it is foggy enough for us to lose sight of the drone, then the flight should be postponed until the weather or visibility gets better.

On the other hand, there are steps that can be taken to avoid losing the visual line of sight of the drone. This would be through the use of drone anti-collision lights.

If using drone anti-collision lights, also referred to as drone strobes, you should only equip your drone with those are FAA approved, meaning that they can be seen by manned aircraft up to a distance of three miles and continually blink.

With anti-collision lights or drone strobes affixed, you will be able to keep track of your drone in the fog (depending on the drones position and the position of the attached drone strobes) and, more importantly, help keep the drone visible to any manned aircraft (low-flying planes or helicopters) in the immediate area.

However, when flying in fog, Visual Line of Sight is not the only concern the FAA has, there is another.

Cloud cover #

Cloud cover is the key ingredient when talking about flying in fog, or not flying in fog. Fog is basically just a cloud (or clouds) at a low altitude.

What does the FAA say about flying in and through clouds?

Below is an excerpt from the FAA that specifically involves clouds and cloud cover:

(d) The minimum distance of the small unmanned aircraft from clouds must be no less than:

(1) 500 feet below the cloud; and

(2) 2,000 feet horizontally from the cloud.
§ 107.51 Operating limitations for small unmanned aircraft.

In Part 107.51, there is little room for misunderstanding.

Part 107 operators are not allowed to fly any closer, vertically, than 500 feet beneath a body of clouds or cloud cover. Again, as fog is basically low-altitude cloud cover, flying through it is prohibited by the FAA.

If the fog is 50 or 100 feet above you, you cannot fly through it as the drone couldn’t possibly be 500 feet below it to avoid it.

Likewise, if fog is 400 feet above you, you would not be able to fly through it as you are also to stay 2,000 horizontal feet from the fog.

Regardless of fog height, the FAA has very specific language prohibiting Part 107 operators from flying through it.

Precautions to take if flying through fog #

With that all said and done, what if you still decide to fly through the fog, perhaps as a hobbyist flying in another country where there are no laws on flying through fog? What can you do to ensure the flight is safe?

Here’s what I recommend.

Minimize the effects of condensation #

Drones are packed with electronics. Most drones are also not waterproof, or even water-resistant for that matter, although there are various manufacturers that do sell waterproof drones.

When you look closely at your drone, you will see various vents and areas around the drone and behind the camera gimbal that can and will allow water (regardless of how much) to get into sensitive areas and wreak havoc on the drone.

To minimize the effects of condensation on the drone, there are a few solutions online from companies that specifically sell kits to make your DJI drones water-resistant.

» MORE: For more information on the effects of water in drones and how to make them water-resistant, please see this article.

Following the steps taken in the article above, your drone will be a bit more tolerant of any water that might try and seep into the internal components.

Disable obstacle avoidance sensors #

This step is something that many of us might not be aware of and pertains especially to drones that are running optical or infrared sensors, in addition to or instead of sonic sensors.

Disabling obstacle avoidance sensors has been a thoroughly tested option for many that have tried to find the best ways to fly in foggy conditions. Why is this step needed?

When fog is especially thick, the drone’s optical or infrared sensors mistakenly see the fog as, well, a solid obstacle, and oftentimes try to land.

Other times, the drone stops or refuses to move, thinking there are solid objects all around it.

Imagine a drone flying over the fog or above a body of water with full sensors on. It might try and land in the water, as has happened to some in the community. Or, as has also been reported, the drone loses control, resulting in erratic behavior and flyaways.

Anti-collision lighting / drone strobes #

As mentioned in the visual line of sight section above, when flying in fog, it is imperative to have eyes on the drone at all times, regardless if you are a commercial pilot, a hobbyist, or a beginner.

The reason, in this case, is twofold, being:

1. Safety of manned aircraft in the area
2. Minimizing the loss of the drone due to a crash, possibly resulting in injury or property damage

» MORE: Best Drone Anti-Collision Lights (FAA Compliant Strobes)

There are many types of drone strobes for sale online.

You will want to look for ones that:

• Can be seen for a minimum of three miles
• Are possibly water-resistant
• Are white or red

Our Pick

Final thoughts #

Technically speaking, drones do have the ability to fly in fog. It is up to individual drone operators as to whether flying in the fog and potentially damaging a drone is worth it without proper waterproofing of the drone.

In the case of US Part 107 operators, as it stands currently as of this writing that flying in fog is prohibited.