Lesson 1.4

Speed, Altitude, Visibility, and Cloud Ceilings

When you’re out in the field—whether you’re inspecting towers, documenting coastal ecosystems, or flying over wetlands—weather conditions and altitude rules matter. The FAA has set specific limits to keep your drone operations legal.

In this lesson, we’ll look at real FAA rules on visibility, cloud clearance, and altitude limits during your missions. These examples will help you recognize safe flying conditions and avoid common mistakes that could lead to violations or accidents.

sUAS Operation Limitations

Max Speed, Minimum Visibility, Max Altitude,

Maximum Speed: 87 knots (100mph)

The sUAS is not allowed to fly faster than 87 knots (100 mph) ground speed.

Minimum Visibility: At least 3 statue miles.

Visibility refers to the distance a pilot can see and identify objects on the ground and in the airspace.

This means that the remote pilot must be able to see the drone and any other aircraft in the vicinity clearly.During sUAS operations, visibility must be at least 3 statute miles.

Field Example: Ocean Ecology Mission

You’re out on the coast to document dune restoration and seabird activity with your drone. Before launching, you check the weather and see visibility is reported at 2 statute miles. Even though the fog looks light, you know FAA regulation rules require at least 3 statute miles of visibility, so you hold off on flying until conditions improve.

Later that morning, visibility increases to 6 statute miles. You run a quick preflight check, confirm you’re good to go, and begin safely capturing your coastal footage within legal limits.

Cloud Clearance: 500 feet below, 2,000 feet horizontally

The sUAS must stay at least 500 feet below a cloud and 2,000 feet horizontally away from a cloud. This reduces the chance of flying into clouds that could block their view.

Field Example: Coastal Wetland Survey

You’re flying your drone along a marshy coastline to document plant health and water levels. As you prep for launch, you notice a low cloud layer hovering above. You check your weather report and estimate the cloud base is around 800 feet AGL—since you’re only flying up to 300 feet, you’re well within the rule to stay at least 500 feet below the clouds.

You also confirm that no clouds are drifting close horizontally—keeping at least 2,000 feet of space to ensure clear visibility and safe flying conditions.

Altitude Restriction: Max Height of 400 ft AGL

The sUAS cannot fly higher than 400 feet above ground level (AGL), unless it’s within a 400 foot radius of a structure and stays below the structure’s topmost point. (We’ll cover this more in another lesson)

Tower Inspection Altitude Restrictions:
Within a 400 ft radius of structure’s topmost point

The sUAS can fly within a 400 foot radius (vertically and horizontally) of a structure’s topmost point

Field Example: Cell Tower Inspection

You’re on-site to inspect a 200-foot cell tower in a rural area. Under Part 107 rules, you’re allowed to fly your drone up to 400 feet above the top of the structure, meaning your max altitude here is 600 feet AGL. You also stay within 400 feet horizontally of the tower to remain compliant while capturing close-up visuals of the antenna and support arms.

Practice Quiz

Operation Limitations: Speed, Altitude, Visibility, and Ceilings

1 / 8

You're flying your sUAS to document changes in a forest's vegetation over the past year. You notice a storm is approaching and decide to increase speed to finish your mission quickly. What's the maximum speed you can fly your sUAS to stay within Part 107 regulations?

2 / 8

You're preparing to fly your sUAS to document water levels in a wetland area, but there’s morning fog. What is the minimum visibility required to conduct your flight safely and legally under Part 107?

3 / 8

While flying over a nature reserve to monitor wildlife habitats, you notice clouds forming above. What should be the minimum distance between your sUAS and the clouds to comply with Part 107 regulations?

4 / 8

You are documenting tree growth in a hilly area with a tall observation tower. What is the maximum altitude you can fly your sUAS if you stay within a 400-foot radius of the tower and remain compliant with Part 107?

5 / 8

You're out in the field documenting changes in a river’s ecosystem with your sUAS. According to Part 107 regulations, what is the maximum altitude you can fly your sUAS above ground level (AGL) to remain compliant?

6 / 8

(Refer to Figure 23, Area 1) You're ecological study team is tasked with inspecting vegetation around a tower located 8 statute miles north of Allendale Airport (AQX). According to Part 107 regulations, what's the maximum altitude you can legally fly your sUAS if you remain within 400 feet of the tower at all times?

7 / 8

(Refer to Figure 23, Area 3) You’re asked to inspect the lighted tower located 4 statute miles SW of Savannah Hilton Head INTL (SAV). What’s the highest you’re allowed to fly under Part 107?

8 / 8

(Refer to Figure 23, Area 2) What are the Visual Flight Rules minimum visibility requirements over Cooperstown Airport?

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According to part 107, what is the maximum groundspeed for a small UA?

A. 87 mph.

B. 87 knots.

C. 100 knots.

Correct Answer: B – 87 knots

Description: The maximum groundspeed for a small UA is:
– 87 knots or 100mph.

Don’t let this question trick you!

Click image to expand

(Refer to Figure 78) You have been contracted to inspect towers located approximately 4NM southwest of the Sioux Gateway (SUX) airport operating an unmanned aircraft. What is the maximum altitude above ground level (AGL) that you are authorized to operate over the top of the towers?

A. 400 feet AGL.

B. 802 feet AGL

C. 402 feet AGL.

Correct Answer: B – 802 feet AGL

Description: Under Part 107, if you are within 400 feet of the structure you can go up to 400 feet above the top of it. The chart shows the tower at 402 feet AGL, making the maximum altitude you can fly above the tower 802 feet AGL.

Note:
Once you find SUX airport you’ll locate the towers 4NM southwest. Here we are able to tell that the tower is still within the fuzzy magenta circle, indicating the Class D airspace it resides in. Due to it being Class D airspace and you would have to get a Certificate of Authorization to operate here.