In this article I want to answer one question: how do drones fly? Basically, we’re going to talk a little bit about the effects of forces on drones. Don’t be like this guy…ouch!
The FAA is clear that the remote pilot in command (what the FAA calls the PIC) is in control and takes responsibility for everything that happens before, during, and after a flight.
If you get a question on the test that deals with ultimate responsibility, chances are the answer will be remote PIC.
A remote PIC should ensure that the drone is properly loaded prior to takeoff. Each drone likely has manufacturer specifications for proper weight and balance and these should be followed for all flights. It is also important to understand that although you should never exceed the maximum weight, there are other factors that should be considered such as the size of the launch area, surface, slope, surface wind, or obstacles.
So, How Do Drones Fly?
Because drones use rechargeable batteries, there is typically no fuel burn to factor into the weight of the drone during flight. A decrease in weight may exist and need to be accounted for if you are somehow dropping off or delivering something. Below are a number of factors you will need to be aware of and have a basic understanding for the test.
Weight
It’s pretty obvious (or should be) that weight has a definite relationship to lift. This relationship is simple but important.
Lift is the upward force on the wing (or rotor if a quadcopter drone) and is required to counteract the weight. With a constant weight, the amount of lift will determine whether an aircraft is accelerating upward or moving downward. In the picture below, if the drone weighs 3 pounds, the amount of lift created by the downward force of the propellers would need to be more than enough to lift 3 pounds or else the drone will continue to stay on the ground. Pretty simple.
Just so that this concept is clear, let’s look at the airplane below. The red arrow represents air traveling underneath the plane’s wing, while the blue arrow represents the air traveling over the plane’s wing. Do you see how the blue arrow has to travel a longer distance than the red arrow? This is what creates lift. In fact, airplane wings are shaped in such a way to encourage lift, which makes sense. This shape is called an airfoil. So on a plane, the engine pushes the plane forward fast enough that the airfoil shape can create enough lift to allow flight. The concept on a drone (or helicopter) is the same, except that the propellers act as the airfoil and spin to create the necessary lift.
Stability
This is the ability of an aircraft to correct for conditions that disturb its equilibrium and is typically designed into the aircraft. It affects two areas significantly: 1) Maneuverability; and 2) Controllability.
Maneuverability is the quality of an aircraft that allows it to be maneuvered easily and to deal with the stresses imposed by those maneuvers. In more simple terms, this is just the ability of a drone to change directions in flight. Drones are usually pretty maneuverable, especially consumer level drones. Controllability is the capability of an aircraft to respond to a pilot’s control as it relates to flight path and altitude. While controllability is related to maneuverability, it deals more with the amount of input required on your controller to make the drone move how you’d like it to move.
Load Factors
A load factor is the force applied to a drone to change it from flight in a straight path because doing so produces stress on the drone’s structure. The amount of this force is the load factor. For the remote pilot, it is sufficient to understand that each aircraft has operating limitations and should be flown within these guidelines in order to ensure safe flight. Below is the load factor chart that is included in FAA-CT-8080-2H (which is provided during your test). As you can see, as the angle of a turn (the bank of the turn) increases, so do the forces against the drone. In real flight, this would probably be associated with a quick, hard turn and in reality, the load factors on the drone would only be for a moment because the controls are probably set up to avoid high load factors for a long time. The point is, the higher the load factor on the drone is, the more lift your drone needs to create to stay in the air.
As an example, a load factor of 3 would indicate that an aircraft is able to withstand a total load of 3 times its weight. Looking at the chart above, when an aircraft makes a level turn at a 60 degree bank, the load factor is two. When the same aircraft makes a level turn at 80 degrees, the load factor is 5.747. Not only is your drone then required to create enough lift to sustain 5.76 times its own weight, continued operation at this unsafe level could cause a system failure. Think of fighter planes and their ability to make hard and fast turns. This is because they are designed to handle huge load factors. Most consumer drones are not.
Drone Maintenance and Pre-Flight Procedures
Drone maintenance and pre-flight procedures are not only an important part of getting your commercial drone license, this is one topic that you should be using each time you fly your drone.
But a remote pilot in command (PIC) is always required to perform regular maintenance on their drone as well as a preflight check on their drone to make sure that everything is safe for flight.
Maintenance
Maintenance on your drones is obviously important and most of the time a drone comes with a maintenance schedule, even if this is loosely defined. It may be in your best interest to come up with a more detailed maintenance schedule if one is not provided by the manufacturer. For the test, the most important thing is to understand that you are required to follow the manufacturer’s guidelines for the drone and all of its parts.
There will be questions about this and, in my experience, the answer is always to follow the manufacturer’s guidelines. The next best advice is just to use common sense when answering these questions. This part of the guide is not particularly in depth because most of the information I could cover will be too in-depth for the test. The maintenance and inspection questions are pretty basic.
Scheduled Maintenance
Scheduled maintenance should be done at regular intervals and should include everything involved with flying your drone. Below is a list of equipment that should be included in your maintenance schedule, but it might not include everything you need in your maintenance schedule.
- Remote Control
- Antennas,
- Control Sticks
- Buttons
- Propellers
- Propeller motors
- Batteries
- Landing gear
- Moving parts (legs of drone etc.)
- Gimbal
- Camera
- Power cords
- Charging stations
- Drone cases
- Firmware updates (for drones, controllers and batteries)
- App updates
Another thing you may want to do is to keep track of your flights, flight hours, etc. This could be great for battery and motor maintenance.
Preflight Inspections & Unscheduled Maintenance
First and foremost, have a preflight inspection list and use it. Print it out and keep it with your drone. The FAA even provides a guide for the things to look at on a preflight inspection. Sometimes a preflight inspection will turn up an issue with your drone, which can require some unscheduled maintenance. Obviously, if you find that a battery is not holding a charge or has a chip in it, this would need to be fixed before flight, even if that just means using another battery and disposing of the broken battery properly. If a propeller blade is chipped, throw it away and use an extra. Most of this is pretty common sense.
Drone Pilot Decision Making
Decision making for drone pilots is broken up by the FAA into a few different concepts, all of which deal with processes for recognizing hazards and risks and dealing with them quickly and effectively.
Crew Resource Management
One tactic recommended by the FAA in decision making for drone pilots is Crew Resource Management (CRM). CRM is all about situational awareness. Despite the fact that your remote pilot’s license will allow you to fly without a “crew” in many situations, the concepts discussed in this section will help you think through all aspects of safety in each situation where you are the remote pilot in command. In particular, instead of managing a “crew,” in many situations you are simply managing a set of resources (battery life, distance of flight, mental capacity, etc.) and attitudes (being level headed when assessing a flight or obstacle).
Hazard and Risk
The FAA highlights a few attitudes that you should avoid and also provides you an “antidote” to those attitudes. They are as follows:
- Anti-authority – “Don’t tell me”
- Instead of having this attitude, you should always maintain to follow the rules because they exist for a reason.
- Impulsivity – “Do it quickly”
- Instead of having this attitude, you should always think first.
- Invulnerability – “It won’t happen to me”
- Instead of having this attitude, you should always think that it could happen to you.
- Macho – “I can do it”
- Instead of having this attitude, you should always recognize that taking chances is foolish.
- Resignation – “What’s the point?”
- Instead of having this attitude, you should always recognize that you aren’t helpless and your actions do make a difference.
Risk
For a remote pilot, who will likely be on his or her own, assessing risk is a crucial tool. It is important to recognize your personal limitations and not add weight to intangible factors such as the need to perform your flight. I know clients can be demanding, but flight safety should always be at the forefront of your mind, no matter the weather or the airspace you are being asked to fly in.
In order to mitigate risk, the FAA has an acronym to help a pilot determine their physical and mental readiness for flying. It is IMSAFE
- Illness – Are you sick?
- Medication – Are you taking an medication that could affect your judgment?
- Stress – Are there other psychological pressures from your job or home life that will affect your concentration?
- Alcohol – Have you have anything to drink in the past 8 hours? 24 hours?
- Fatigue – Am I tired or not well rested?
- Emotion – Am I emotionally upset for some reason?
The PAVE Checklist is another way to mitigate risk. This should be incorporated into your pre-flight planning to ensure that you have covered every aspect of the flight:
- Pilot-in-Command
- Am I ready for this flight?
- Aircraft
- Are you flying the right aircraft?
- Are you familiar with this aircraft?
- Can this aircraft carry the planned load?
- EnVironment
- Weather
- Consider ceiling, visibility, forecast, presence of clouds, icing, current temp.
- Terrain
- Airspace
- Weather
- External Pressures
- Take an objective look at whether you are able to safely complete the flight or if pride is a factor in your decision. Pride can be a surprisingly powerful force.
Decision Making for Drone Pilots: Another Process
Single Pilot Resource Management
Single Pilot Resource Management is a concept about how to gather information, analyze it, and make informed and timely decisions. No matter the specific process you use, it is important to develop the skill of analyzing each situation in light of your experience level, personal minimums, and current physical and mental readiness.
Perceive, Process, Perform (3P) Model
- Perceive the set of circumstances for a flight
- Process by evaluating their impact on flight safety
- Perform by implementing the best course of action
This method is best understood in context of an actual situation. We recently had a job with my drone company where we were taking pictures of a small building for an internet services provider. When we got to the site, we perceived that there was also a cell tower at the location. We processed this information by recognizing that we would need to navigate around the cable attached to the tower ,and we performed by implementing that plan and navigating more carefully around the cables.
Automatic Decision Making
This concept deals with how someone makes a decision when placed under time constraints, or faced with a task that has a lot of uncertainty. Instead of weighing pros and cons for numerous options, a person will typically try to determine whether the situation is familiar and take the first workable option they can find. Basically, this is the idea that your ability as an expert depends on your ability to recognize patterns inside of complex situations.
Use of Resources
As I mentioned above, your use of resources in a flight is key to a successful flight. There are a number of resources in a drone flight to be aware of. These include battery life on your drone, controller, or viewing device, as well as any limitations you have on flight distance or altitude. These also include environmental factors, such a temperature, humidity, noise, vibration, etc. This also includes your own physiological stress such as fatigue, lack of physical fitness, sleep loss, low blood sugar, or illness. Finally, these could also include psychological stress like death in the family, divorce, demotion at work, etc. Be aware of these factors and do not downplay them when flying your drone commercially.
Situational Awareness
This concept deals with the accurate perception and understanding of the factors and conditions within the fundamental risk elements that affect safety before, during, and after the flight. The important thing when you are pilot-in-command of a drone is that you do not fixate on any one factor, but that you have a full understanding of all the factors involved in your flight. In real life, it won’t be acceptable that you were fixated upon the wind as a factor in flight and failed to realize that you were also flying close to a helipad with traffic. You must work to keep the entire situation and its various factors in your mind when flying.
Emergency Procedures
The most important thing to remember about emergency procedures is that the FAA allows you, as a remote pilot in command, to deviate from any of the Part 107 regulations in response to an emergency. If you do so, you may be asked by the FAA to report the emergency and the deviation from the rule.
The way I typically envision a scenario like this is that you are flying and, out of nowhere, a helicopter appears over the horizon. You are flying at a legal altitude, not even in controlled airspace, but you are forced to go above 400 feet above ground level in order to make sure the helicopter can properly pass through. There simply is no time to react differently. This is an acceptable emergency procedure given the circumstances. While there are any number of emergency situations that could require you to break a Part 107 regulation, I’m simply providing one example here.
Secondarily, it is important to know that part of being prepared in an emergency is avoiding one altogether. Many issues with your drone can be handled by simply conducting a pre-flight inspection or conducting regular maintenance. In addition to this, if you are using a visual observer or some other crew member, you need to provide a briefing to that party to let them know the plan in the event of an emergency.
Drone Pilot Performance
There are a number of factors that can affect drone pilot performance. We touched on some of those factors in the last section. Below is a list of these factors and how they can affect performance. Most of this is common sense. If you get a question on the Part 107 knowledge exam involving the topics in this section, do yourself a favor and choose the safest one. Safety is the FAA’s main priority and they want you to keep safe flying top of mind.
Hyperventilation
This is the excessive rate and depth of breathing that leads to an abnormal loss of carbon dioxide. Symptoms include visual impairment, lightheaded or dizzy sensation, tingling or hot and cold sensations and muscle spasms. Treatment for this condition includes simply slowing the rate of breathing or breathing into a bag.
Stress
This is your body’s response to physical and psychological demands that are placed upon it. Stress can be caused by a myriad of factors and typically falls into one of two categories: acute (short term) and chronic (long term). Pilots should be aware of both types of stress in their lives and ensure that their performance as a pilot is not affected.
Fatigue
This condition is commonly associated with pilot error and also occurs as acute or chronic fatigue. Acute fatigue can be prevented by proper diet and adequate rest or sleep. A UAS pilot should not fly if under the effects of acute fatigue. Those suffering from chronic fatigue should consult a physician.
Dehydration
This condition is the critical loss of water from the body. Obviously, it is important to stay hydrated, whether you are flying or not. Try carrying a water bottle and staying ahead of your thirst.
Heatstroke
This condition is caused by any inability of the body to control its own temperature. It commonly occurs when dehydrated. Stay hydrated.
Drugs
Aside from illegal drug, which should obviously be avoided there are thousands of legal, over the counter or prescription drugs that have been approved by the FDA. Be wary of those medications that potentially cause adverse side-effects (drowsiness or cognitive deficits).
Alcohol
Obviously, alcohol impairs the efficiency of the human body. It is important to recognize that you should avoid piloting a drone or aircraft of any kind (or cars and machinery for that matter) while intoxicated. These activities should also be avoided if hungover, as your body is still under the influence of alcohol. You must avoid flying for at least 8 hours and your blood alcohol level should be .04% or lower.
Vision & Flight
A remote pilot in command should use a scanning technique that starts at the distance farthest from the aircraft looking either left to right or right to left and working their way in towards the aircraft. Short stops are okay but your scan should be continuously moving about your field of view.
As you can see, there are a number of things that can affect drone pilot performance and the FAA simply wants you to be aware of how these factors can affect a safe flight.
