Even the best hardware and software may fail. So far, considering missions with even the highest level of autonomy, there is always a human operator whether controlling a UAV directly or monitoring mission progress, ready to step in, if necessary, to correct the mission or abort it.

On the other hand, humans are the most common factor of failure, due to their nature.

The drone operator is frequently named as UAVO (UAV Operator), regardless of the flight nature (autonomous, fully manual, VLOS/BVLOS/FPV).

Aviation learned the lecture and introduced a tight verification system, based on procedures that are updated on every air catastrophe or even slight incident reported, to avoid such situations in the feature. Thanks to this approach, aviation became the safest traveling method (well, almost, lifts seem to be safer, anyway). Drones are naturally sharing part of the aviation world, but on the other hand, freedom of purchase, mass scale of the operations (mostly RC, unregistered) is naturally so much different than the hermetic world of pilots and ground staff.

Anyway, many of the rules, hints, and regulations, as well as good practices for airmen can be adapted for UAVOs, directly wor with slight modifications.
Below we consider human limitations and some of the good practices for UAV operations.

Starting a career as UAVO is somehow like learning, how to drive. In the beginning, operations seem to be magic and a bit scary, along with the growing experience they become natural and then switch to the routine. And the routine leads to mistakes.
In aviation, there is a known phenomenon, the so-called “dead zone”, where a new pilot starts to operate on his own. Most of the flight accidents and incidents happen between 50 and 350 flight hours. Similar phenomena apply to the UAVOs but the exact flight experience time is under investigation. Once UAVO gets used to fly, there appear shortcuts in operation preparation, and that leads to accidents. While many UAV accidents are not deadly and most of them finish with hardware damage only, some may cause serious effects on 3rd parties, not only the wallet. Drone operations are not so strictly described as in the case of the plane operations but this tends to change, i.e. along with the introduction of the standard and non-standard scenarios for drone operations, as standardized across UE (the details are present in the drone regulations chapter.
Because drone operations can interact with other airspace users, it is common that UAVOs require professional certification, regarding operation place and drone MTOM (Maximum Take-Off Mass). It is common that devices below 250g are considered as toys, and those equal and above may require certification to operate, regarding operation location, altitude, and many other factors. Keep in mind that EU standardization is a process at the moment of writing this manual and local regulations may vary.

One of the best-known conceptual models of the human factors related to aviation (and thus drone operations to some extent) is the so-called SHELL model. It was introduced by Elwyn Edwards in 1972 and is composed of the following components:

• Software: should not be understood as computer software only, but also instructions, aviation regulations, policies, procedures, customs as well as habits and practices.
• Hardware: all physical components that constitute the UAV ecosystem.
• Environment: operational environment, including physical factors like air pressure, humidity, clouds, fog, etc.
• Liveware that is a human component of the model (here UAVO), their limitations performance and capabilities.

Human-operator due to its nature is limited. Knowing the limits is essential for understanding operation challenges and avoiding unnecessary risk, eventually handling it properly.
Following limitations are to be considered when getting ready for operation:

• Tiredness: impacts both operation preparation as well as handling of the operation-it causes low focus.
• Mood: anxiety, low mood impacts strongly focus and emotionless approach to critical situation handling.
• Diet: inappropriate diet may cause a lack of concentration, i.e. use of too much caffeine.
• Drugs: as in the case of driving, flying a drone while using narcotics and alcohol is strictly forbidden in most countries.
• Sight: in the case of the VLOS operations, being able to observe drones is necessary. This limits ability to position drones in 3D space and also determines operation range.
• Experience: being experienced UAVO is usually an advantage but there is a risk of drifting towards shortcuts as discussed above.
• Illness: some diseases exclude being a UAVO at all, while others limit operation class and MTOM category: i.e. diabetes, heart diseases, and so on.
• Environment: the presence of other people and related disturbances may impact focus.

It is also worth to mention, that the human brain has limited perception capabilities, i.e. a need to stabilize a quadcopter at least 100x per second (usually much faster), disables direct motor control. Because of it, every multirotor requires an FC, that performs platform stabilization autonomously and without FC, a human cannot control motors directly.

Statistics are inexorable: around 80% of the accidents/incidents are caused by the human factor.

Most of the drones and related infrastructure nowadays bring the capability to update their software (firmware). As it is not common, sometimes developers introduce new features that impact behavior and user interface. For this reason, it is strongly not advised to update drone firmware/software right before the operation, but rather to do it in a spare time and give it necessary testing, to avoid surprises.

Regarding open-source FC firmware, the common situation is a requirement to reset all settings, once updated with major revision. That simply means each drone construction has to be re-configured with care after each update and all functions and procedures should be checked.

Aviation is considered to be safe, because of the procedures, strictly and precisely describing each operation. A similar approach is being introduced in drone operations, so many certified UAVOs keep procedure charts to refer to it.
Those procedures are in short describing three main stages of the drone operation:

• Before the operation: everything, starting from planning, prior take-off;
• During the operation: includes also handling of the critical situations;
• After the operation: everything, starting right after landing, until the operation is finished; This may include also data processing, if necessary;

Each stage should be carefully prepared and tailored to the particular components, including (among others) drone, ground station, communication, and remote control. It is common to have paper or electronic checklists, describing carefully each step of the particular procedure, the similar way the pilots do checklists. In the case of the UAVO, it is uncommon that the procedure checklist is being processed by two persons (as in the case of the passenger planes), as most UAVOs work single. Some basic approaches to the procedures can be found on the Internet and they are also provided by drone manufacturers, along with the device purchased.