Lesson 5: the core limits of flying

Welcome back, remote pilots in training! 

You’ve learned many of the rules before flying. Today, we’ll start a new chapter, where we’ll cover the core rules while flying in the sky!  Before we talk about those rules, there are some important definitions for pilots to know. Let’s get them out of the way! 

MSL vs. AGL  

Measuring altitude from the sea and the ground

Altitude Adventures Await! 

Pilots rely on accurate altitude measurements to navigate safely and avoid obstacles like buildings, mountains, and other aircraft. Makes sense, right? Did you know there are different ways pilots measure how high they are? They use the sea and ground as two references to measure altitude!

• Mean Sea Level (MSL) is the average height above standard sea level. It gives us a reference point for altitude, no matter where the ground below it is! 

• Above Ground Level (AGL) is the height above the ground. It measures the distance between the top of an object and the Earth’s surface.

Throughout this class, we’ll be using these two different ways to measure height all the time. 

Visual Line of Sight 

What’s Visual Line of Sight (VLOS)? 

Keeping a  visual line of sight means being able to see your drone all the time during your flight. 

Real quick, whose main job is it to see the drone at all times on a crew during a drone mission?

That’s right! It’s the Visual Observer’s main job!  

Rules

1. You always have to maintain VLOS when flying

2. You can't use binoculars or the drone's camera to see it.

3. If you wear glasses or contacts, that's okay.

When can you break Visual Line of Sight?

Exceptions

1. You can fly without seeing (and break VLOS) it if you have a special waiver

2. Brief moments where you don't see if it's for safety or needed for your task.

Welcome back! I’m sure you’ve been wondering how high, far, and fast you’re allowed to fly your drone. 

The FAA has rules for this! We’ll keep coming back to these core roles a lot throughout this course, so don’t forget them! Just like cars have rules, so do drones! Imagine if cars on the freeway didn’t have speed limits, and they all drove at 120 MPH! Not very safe, right? Cars need to be regulated by the government and have clear limits. Drones do, too! 

The Core Limits of Flying Your Drone

Let’s quickly introduce what all of the rules all are, and then dive into what each one means. 

•    Maximum Speed  - 100 MPH  

•    Maximum Altitude  -  400 Feet AGL 

•    Minimum Visibility  -  3 Statute Miles 

•    Distance from clouds  - 500 feet below clouds 

•    Distance from clouds - 2,000 feet next to clouds  

Speed 

How fast do you think you’re allowed to fly a drone?

The maximum speed you can fly your drone is 100 MPH. That’s the equivalent of 87 knots! Hold on – Ugh… What’s a Knot ?  

It’s time to peel the onion! 

Hello! You’ll be seeing a lot more of me today, and I’m not here to gatekeep. Let’s talk about knots! And knot the way to tie a rope. Sorry if that made you cringe! 

Knots are just another way to measure how fast something’s moving, like a plane or a boat! Pilots use knots because not everyone in the world measures stuff in miles. All you need to know is – 100 MPH means 87 Knots.  

What’s the fastest you can fly a drone?  

1. 1 MPH

2. 10 MPH

3. 100 MPH

4. 500 MPH

Height 

What’s the highest you’re allowed to fly?!

The maximum altitude (height) you can fly your drone is 400 feet Above Ground Level (AGL). You can fly your drone up to 400 feet above the ground.

But did you know you can also fly it 400 feet above the highest point of a tower? 

Plus 400 FT above the tower!  

How high can you fly a drone above the ground when not above a tower?  

1. 50 feet

2. 150 feet

3. 400 feet 

4. 1,000 feet

How high can you fly above the ground if you’re flying over a tower?  

1. 150 feet

2. 400 feet

3. 800 feet 

4. 2,000 feet

Now, let’s say you have to inspect a tower that’s 330 feet high. What’s the highest you can fly? 

1. 130 feet

2. 400 feet

3. 730 feet

4. 800 feet

Great work! You just add 400 feet to the height of the tower, and you get 730 feet. So in this scenario, the maximum altitude would be 730 feet AGL - the highest you’re allowed to go. 

Visibility 

How far do you have to see a drone for? 

Before we ask the next question, we should know what Minimum Visibility means, first. Any guesses? 

Visibility means whether or not you can see something, and changes depending on weather conditions! Minimum visibility is the shortest distance you need to be able to see clearly to ensure safety, especially when flying an aircraft.

Minimum Visibility 

You need to be able to see at least 3 miles in front of you to fly your drone safely.

Imagine you’re looking down a very long road. You should be able to see everything on that road for at least 3 miles down. If you can see that far, it’s safe to fly your drone. The 3SM visibility rule ensures that you have a clear view of the sky for at least 3 miles ahead, allowing you to see any obstacles or changes that might impact your drone's safe operation.

3+ miles of visibility ✅   

It can be hard to imagine a distance that’s 3 miles long! Let’s look at some examples. 

• 2.5 Miles = Central Park 

• 3 Miles = Golden Gate Bridge x 2  

If you can’t see 3 miles ahead of you, it’s probably not very safe to fly your drone. Don’t fly!  

Alright. So, pilots usually measure visibility with something called ‘Statute Miles.’ 

Hold on – What are Statute Miles?  

It’s time to peel the onion! 

A Statute Mile is the same as a regular mile, but is the official term that more countries use. You’ll see regular miles referred to as Statute Miles, or SM, a lot as a pilot. 

How far do you have to see in front of you?  

1. 1 SM 

2. 3 SM 

3. 15 SM

4. 100 SM

Clouds 

How far do you have to steer clear of clouds? 

The sky isn’t a free for all! And flying in a cloud can be really dangerous. You won’t see your drone (bad visibility!) and you can lose it. The cloud clearance rule is about making sure your drone stays far enough away from clouds. Hence, it stays clear of them! 

500 Feet Below 

Your drone needs to fly at least 500 feet below any clouds.

2,000 Feet Away 

Your drone should stay at least 2,000 feet away from the side of any clouds. 2,000 feet seems like a big number, but it’s less than half a mile - which is about 2,600 feet. 

And, since we’re talking about clouds – 

Let’s talk about a term you’ll see pilots use a lot to talk about them, and that’s cloud ‘base’ and cloud ‘ceiling.’ 

Cloud Base and Ceiling 

A cloud base is the bottom of the cloud (the base). It’s where the cloud starts if you’re looking at it from the ground. It’s the lowest part of a cloud that is visible from the ground. So, a cloud base is the height above the ground where the cloud starts. If a cloud base is 1,000 feet, that means the cloud is 1,000 feet above the ground! The cloud ceiling is the height where the clouds cover most of the sky, like a blanket of clouds starting at a certain height. Think of a cloudy day where almost the entire sky is covered with clouds. If you look up and the clouds start at 3,000 feet above the ground, that’s the cloud ceiling. The cloud ceiling only applies when it’s very cloudy. On a clear day, there isn’t a cloud ceiling because there aren’t enough clouds to measure.

Nice work! You’re getting good at this. Now, let’s wrap up this section on cloud clearance and the core rules of flying. 

How close can you fly below a cloud?  

1. 1 FT 

2. 33 FT 

3. 500 FT 

4. 40,000 FT 

How close can you get next to a cloud?  

1. 1.5 FT horizontally 

2.  18 FT horizontally 

3. 800 FT horizontally 

4. 2,000 FT horizontally 

Waivers 

How to break the rules – legally, of course! 

Great! So, the next topic of today is waivers – and why they’re important. 

A waiver from the FAA is a special certificate that allows you to do something you’re not normally not allowed to do under Part 107 rules. A waiver is a legal way to break these rules! You need  special permission if you want to break certain rules, like flying over 400 feet, at night, over people, in controlled  airspace, and so much more!  We’ll talk about controlled airspace in the next chapter. 

Heads up! Getting a waiver is hard. 

You have to write a letter to the FAA, like a pitch that tells them all the details and how you plan to fly safely. 

How to Apply for a Waiver

• Detailed plan

• Safety justification

You can apply for Airspace Authorization through the FAA Drone Zone.

Do you Remember? What else can you use the FAA Drone Zone for? 

• Register your drone 

• Update contact info  

• What else can you use the FAA Drone Zone for? 

• Do you Remember? 

• Report a lost or stolen drone  

• Reporting accidents

• Applying for waivers

The FAA aims to review and decide on waivers within 90 days. Approved waivers may come with additional safety rules to follow.

We mentioned waivers earlier today, related to a key term! What was it? 

Excellent work!