Is an Assistant Necessary for Drone Surveying? Four Criteria for Determining Safe Operation

Table of Contents

• Is an assistant always necessary for drone surveying?

• Assessment Criterion 1: Flight Methods and Required Safety Measures

• Assessment Criterion 2 Surrounding Environment and Third-Party Access Control

• Judgment criterion 3: Workload concentrated on a single pilot

• Assessment Criterion 4 Emergency Response and Communication System

• Roles and responsibilities to define when assigning an assistant

• Worksites where it is easy to operate without an assistant and worksites where it is difficult

• Summary

Is an assistant always necessary for drone surveying?

Many practitioners responsible for drone surveying first worry about whether an assistant is legally required, or whether they may fly alone. To conclude, it cannot be said unconditionally that an assistant is absolutely necessary at every drone surveying site. However, national training guidelines and aviation bureau standard manuals basically require assigning the number of assistants necessary to ensure safety and establishing a system in which they mutually confirm safety, and operations without assistants are premised on being able to ensure equal or greater safety through measures such as access control. In other words, whether an assistant is necessary should be considered not merely as a matter of “having personnel present or not,” but as an operational-design issue of “whether safety can truly be guaranteed at that site.”

In particular, drone surveying, unlike simple aerial photography, is work that requires performing on-site checks before flight, management of takeoff and landing points, safety checks of the flight route, attention to surrounding workers and vehicles, confirmation of camera settings and data acquisition status, and verification of results after the flight, all in quick succession in a short time. The more tasks the operator must handle alone, the more likely it is that attention to matters other than the operation of the aircraft itself will be insufficient. Therefore, it is practical to determine the need for an assistant not by whether a flight can be conducted, but by whether surveying can be performed safely, stably, and with reproducible results. The training manual also requires that, when assigning assistants, roles and means of communication be made clear and a system be established to enable safety checks.

Evaluation Criterion 1 Flight Methods and Required Safety Systems

The first criterion for determining whether an assistant is necessary is what kind of flight method will be used for the survey. If the flight is conducted during daytime within visual line of sight, with both the takeoff/landing site and the flight path clearly visible, and in a place where third parties are unlikely to enter, there may be room to establish a safe setup without placing an assistant. On the other hand, the need for an assistant rises sharply for flights beyond visual line of sight, night flights, flights where it is difficult to maintain a sufficient distance from people or property, flights in areas densely populated with people and houses, and flights at higher altitudes where notifying the surrounding area and coordinating with relevant agencies becomes important. The Aviation Bureau’s standard manual also requires additional arrangements depending on the form of flight, and there are situations in which monitoring and advice from an assistant are assumed for flights beyond visual line of sight, night flights, and flights that cannot maintain a distance of 30 m (98.4 ft).

For example, in beyond-visual-line-of-sight flights, procedures require confirming before flight that no third parties are beneath the route and conducting flights under an assistant equipped with binoculars or similar aids. In addition, for night flights the assistant is required to understand the aircraft’s characteristics, and when combined with beyond-visual-line-of-sight operations there must be a system in which the assistant checks the aircraft’s orientation and attitude and advises the pilot as necessary. In other words, at sites where the survey area is wide and visibility is temporarily lost, where terrain undulations make the aircraft hard to see, where the aircraft passes into the shadow of structures, or where work extends until near sunset, planning on the assumption of single-operator operation itself becomes precarious. The more complex the flight method becomes, the assistant is not merely “reassuring to have” but becomes “part of the safety system.”

Furthermore, in flights where it is difficult to maintain distance from people or objects, the role of an assistant becomes even clearer. The standard manual requires assigning an assistant, when certain protective measures are not in place, to monitor that third parties do not enter the flight path, to advise the pilot if an approach or intrusion occurs, and to take safety measures such as aborting the flight. When surveying construction sites or temporary yards, it is easy to assume safety because site personnel are present, but in fact the mere presence of people on site can increase the need for an assistant. This is because situations such as flying at low altitude for surveying purposes or workers moving near takeoff and landing areas require eyes other than the pilot’s.

Assessment Criterion 2 周辺環境と第三者の立入り管理

The second criterion is how much you can control the surrounding environment. A site where an assistant can be considered unnecessary is not simply a place with few people. What matters is whether you can actually control third-party entry. The aviation authority's standard manual states that if you can clearly mark an access-controlled area by installing walls, fences, signs, cones, etc., and thereby reliably restrict third-party entry, this can be used in place of deploying an assistant. Conversely, if cones are simply placed casually so that anyone can cross through, that is a weak basis for operating without an assistant.

What is easy to overlook at drone surveying sites is the assumption that "it's on the premises, so it's fine." Construction yards, material storage areas, reclaimed land, slopes, riverbanks, and areas around farmland may appear to be places where only authorized personnel enter, but in reality delivery vehicles, passing vehicles, patrols, nearby stakeholders, and workers from other teams may come and go. If the movement routes of third parties are even slightly difficult to predict during surveying, it is highly valuable to assign an assistant. The assistant is not merely a lookout: they share the hazardous area before flight, warn people who are about to enter, and, if necessary, help lead the decision to stop the flight. Even the standard manual requires that the assistant prevent entry into the flight area, watch the entire flight path to monitor the aircraft's condition and changes in weather, and provide necessary advice.

On the other hand, there are environments where operations without an observer are easier to consider. Guidance for conducting beyond-visual-line-of-sight flights without an observer lists places where the likelihood of a third party being present along the flight path is low: mountains, marine areas, rivers and lakes, forests, agricultural land, golf courses, or similar locations. That does not mean these places are unconditionally safe, but at least from the perspective of managing third parties, they are certainly easier to arrange than urban areas, roadsides, areas adjacent to residential neighborhoods, or active construction sites. Therefore, the need for an observer should be considered not in terms of whether the place is wide or narrow, but in terms of how much you can reduce the possibility of third parties entering unexpectedly.

Judgment Criterion 3 Workload Concentrated on a Single Operator

The third criterion is how much work is concentrated on a single operator. In drone surveying, the job is not just to fly the aircraft safely. On site, far more decisions happen simultaneously than you might expect: checking the flight plan, performing a final check of the survey area, ensuring the safety of takeoff and landing points, communicating with workers, monitoring the surroundings during flight, checking the condition of collected data, deciding when to swap batteries, arranging the next flight, and deciding whether to abort in case of abnormalities. Trying to handle all of this alone means some checks will be neglected. Even highly skilled pilots become slower to decide as the amount of information increases. That is why whether an assistant is present should not be determined solely by the pilot’s years of experience.

In surveying operations in particular, the requirement is not to "fly and be done" but to "deliver results that meet the required accuracy." For example, when factors overlap—such as wanting to check acquisition status to avoid retakes, wanting to see whether terrain or structures are creating shadows, and wanting to observe ground conditions at each takeoff and landing—the pilot's attention is drawn away from the aircraft. If an assistant is present, they can be tasked with perimeter monitoring and checking for intrusions, allowing the pilot to focus on controlling the aircraft and making flight decisions. The reason the guidelines require confirming roles and ensuring means of communication when an assistant is used is precisely that this distribution of cognitive load is directly linked to safety.

A common on-site judgment is, "It's fine to be alone because it flies automatically." However, even with autonomous flight, the final decision and intervention when danger occurs are made by humans. Detecting intruders, responding to sudden gusts, monitoring aircraft overhead or other airframes, interrupting operations during abnormalities, and securing an emergency landing site—these cannot be completed by automation alone. The higher the proportion of autonomous flight at a site, the more the operator's role shifts from "the person who flies" to "the person who supervises." If it is difficult for one person to carry out that supervisory work alone, an assistant should be assigned. The assistant is not a substitute pilot but functions as an external pair of eyes to prevent the operator from making incorrect safety judgments.

Evaluation Criterion 4: Emergency Response and Communication System

The fourth criterion is how quickly you can respond in the event of an anomaly or emergency. The biggest difference caused by having or not having an assistant appears not during normal operations, but at the moment something happens. The Aviation Bureau's standard manual requires that, even when conducting flight beyond visual line of sight without an assistant, procedures be established to safely land the aircraft in the event of unforeseen circumstances such as aircraft malfunctions, intrusions by third parties, approaching aircraft, or weather exceeding operational limits, and that emergency landing sites be selected in advance and inspected on site before flight. It also states that, as needed, arrangements should be made to contact police stations, fire departments, and other relevant agencies. In other words, operating without an assistant should not be understood as "a way to reduce personnel and make things easier," but rather as an operation that requires more rigorous advance planning.

Imagine it on site and it becomes easy to understand. While flying a short distance away from the takeoff/landing point, if an intruder appears, another aircraft approaches from above, a sudden gust causes unexpected movement, or a system warning comes on, the operator must decide whether to continue or abort the flight while watching the aircraft. At the same time, it's too much for one person to also alert nearby people, direct workers to evacuate, make initial notifications to contacts, and confirm the safety of an emergency landing site. If an assistant is present, the operator can focus on flight decisions while the assistant secures the surroundings and handles initial communications. Whether this division of roles exists or not greatly changes the speed of response in abnormal situations.

Also, if you operate without an assistant, you need to raise the quality of on-site checks. Before flight you must work through points such as where a third party might enter, where a safe landing can be made, how the wind flows through the site, whether there are locations with obstructed sightlines, and where work vehicles will pass. At sites where an assistant is present, this information can sometimes be covered through division of roles, but without an assistant the pilot must shoulder it alone. That is why “being able to fly alone” and “should flying alone” are separate issues. If you prioritize safe operation, deciding to have an assistant is a reasonable choice at sites where you have concerns about the initial response in an emergency.

Role assignments to decide in advance when appointing an assistant

Even if you decide to assign an assistant, simply adding one person does not automatically make operations safer. Before flight, you must clarify who will monitor which area, who will call out and how when a third party enters, what the signal for aborting the flight will be, who will support the decision to switch to an emergency landing, and what means of communication—such as radios or phones—will be used. Training materials also require that when assigning an assistant, roles be confirmed and communication channels with the pilot secured, so that a structure capable of verifying safety is in place. Even with an assistant, if roles are vague, an actual abnormal situation is more likely to lead to confusion.

Also, the number of assistants is not fixed at one. The standard manual specifies "the necessary number of assistants" and indicates that you should check in advance the potential impact on people and property near the flight site and, if necessary, increase the number of assistants. On long embankments, graded sites with limited sightlines, yards where multiple traffic routes intersect, or linear sites along roads, a single assistant may not be able to oversee the entire flight path. In such cases, whether the monitoring coverage is sufficient is more important than the mere fact that an assistant has been assigned. If the site is complex but you try to keep the number of assistants to a minimum, you will ultimately leave gaps in safety.

Worksites That Are Easy to Operate Without an Assistant and Worksites That Are Difficult

Sites that are easier to operate without an assistant are those for daytime visual-line-of-sight flights with good visibility, clearly defined takeoff and landing points and flight paths, easy management of third-party access, simple flight routes, and readily available emergency landing spots. For example, on a large site where working hours can be adjusted, in a section where the movement of relevant personnel can be blocked off in advance, or in locations with little public traffic nearby, it is easy to indicate an access-control area using fences, cones, and signs, and to create a setup in which the pilot can comfortably keep track of the aircraft and its surroundings. At such sites, instead of assigning an assistant, carefully conducting on-site pre-flight checks and access control makes safe operation more likely.

Conversely, sites where operation without an assistant is difficult include those facing roads, those with pedestrian or worker traffic nearby, those where terrain or structures break line of sight, those requiring repeated takeoffs and landings, those with surveying areas that are long and narrow, those involving beyond-visual-line-of-sight or night flights, and those with few emergency landing sites. Even in places with few third parties, such as forests or farmland, the difficulty of single-person operation increases if trees or undulations obstruct the line of sight or if recovery and communication in an emergency would be difficult. Conversely, even in a corner of an urban area, if access can be reliably controlled by time periods and the flight area is limited, there may be room to consider operation without an assistant. In other words, whether an assistant is required is determined not by place names or site names but by manageability and responsiveness.

What’s important here is not to pursue “no assistants = personnel reduction” as the sole objective. Drone surveying must prioritize preventing accidents above all, and on that basis it is work that must adhere to the required accuracy and procedures. Even if you remove one assistant, if retakes and re-flights increase, you will ultimately increase both man-hours and risk. Especially at first-time sites, at sites where the work flow is hard to read, or at sites where multiple trades are working simultaneously, it is less prone to failure in practice to first establish safety procedures with an assistant present and, after you have grasped the actual conditions of the site, consider the potential for reducing personnel. Safety arrangements should be decided not only by logic but also by taking each site’s particular quirks into account.

Summary

Whether assistants are necessary for drone surveying cannot be answered uniformly. The basic idea is that the need for assistants increases as flight methods become more complex, as it becomes more difficult to control third-party access, as the workload concentrates on a single pilot, and as the initial response required in emergencies becomes more demanding. National training regulations and aviation authority standard manuals also present the basic approach of assigning the number of assistants necessary to ensure safety, while allowing substitution through certain access-control measures. Therefore, in practice, it is important to judge not by the binary question "Are assistants necessary?" but from the perspective "Can equivalent or greater safety truly be achieved without assistants?"

In surveying field operations, it is necessary to balance accuracy and safety not only through aerial data acquisition but also by including ground checks, handling of control points, as-built verification, and position cross-checks. If you want to quickly carry out ground-based position checks while maintaining on-site safety protocols, the idea of combining an iPhone-mounted high-precision GNSS positioning device like LRTK can also be effective. To stabilize drone surveying operations without undue strain, it is important to set up a system that covers not only aerial operational design but also the ease of ground verification; this will ultimately lead to both improved safety and productivity.