# BVLOS Unmanned Aircraft Operations in Forest Environments
## 3 BVLOS Operations
### Scenario 2: Hard BVLOS  
Scenario 2 represents another realistic scenario, within the forestry sector, whereby data capture is requested over an entire forest estate: in this case, one that is just under 6000 ha and comprised of steep terrain and mixed age classes of trees. There are some points from where the operation could take place, enabling a clear line of sight for the C2 link; however, the distance from the vantage point to the edge of the forest is 8 km, which means that the operation could not be done within VLOS. The operating area for scenario 2 is shown in Figure 4.  
\begin{table}
\begin{tabular}{c c c} \hline \hline \multicolumn{1}{c}{\multirow{2}{*}{**Variable**}} & \multicolumn{2}{c}{**Scenario**} \\ \cline{2-3}  & **1. Soft BVLOS** & **2. Hard BVLOS** \\ \hline Area of interest (AOI) & \multicolumn{1}{c}{Mature stand of _Pinus radiata_} & Large forest estate \\ Forest height & \(\sim\)40 m tall & Mixed age class (0 to \(\sim\)40 m tall) \\ Area & 20 ha & \(\sim\)6000 ha \\ Max distance from operator & 0.5 km & 8 km \\ Terrain & Flat & Steep \\ Take-off location & Small kid site surrounded by tall trees & Open skid with good vantage over AOI \\ Surroundings & Stands of same age class on all sides & Bordered by other forested areas (native \\  & & and plantation) and farmland \\ VLOS over total AOI & No & No \\ Use of EVLOS an option & No & Yes \\ Use of MEWP an option & Yes & No \\ \hline \hline \end{tabular}
\end{table}
Table 2: Summary of the variables that impact upon scenarios 1 (Section 3.1) and 2 (Section 3.2).  
In Scenario 2, VLOS is not possible with or without a MEWP because the distances involved are too far. However, it is possible to perform EVLOS by positioning visual observers on ridges around the estate. The difficulty with this is that there needs to be overlap amongst visual observers so that VLOS is never lost, and there also needs to be clear training around visual scanning, handover procedures, and standard phraseologies for communications. An additional consideration in forest environments is that it may be difficult to access the required vantage points, and a lot of time might be used up positioning visual observers. Those visual observers would also be paid for their work and may need travel expenses and accommodation paid for, especially if operating in a remote area. For these reasons, BVLOS is the more efficient and pragmatic option. Regardless of whether it is an EVLOS or a BVLOS operation, there will be common issues related to whether the C2 link is capable of securely covering the entire operating area and whether the aircraft has a large enough power supply to avoid regularly returning to the take-off point. In this sense, the most likely platform will be a fixed-wing vertical take-off and landing (VTOL) aircraft, as these have longer flight times due to superior aerodynamics and subsequent efficiency in power consumption [24]. For BVLOS, there will also need to be sufficient payload to carry the combination of remote sensing equipment and the necessary systems to detect and avoid other aircraft.  
Figure 3: Example of the operating area in Scenario 1 (Soft BVLOS), a circa 20 ha stand of mature _P. radiata_ surrounded by stands of equivalent age. The operating area is depicted with a green outline, with potential take-off locations marked as yellow crosses.