Planning a BVLOS flight: detect and avoid, C2 link and contingencies

Beyond visual line of sight the pilot loses the most important safety tool: their own eyes. A good BVLOS plan replaces them with procedures, equipment and margins.

Ground risk and air risk

A risk assessment looks at two things:

• Ground risk: people and critical property that could be hit if the RPA comes down. Route over unpopulated land and keep a buffer between the flight path and people.
• Air risk: a collision with a manned aircraft. Avoid aerodrome approaches and known low-level routes, and plan when to fly.

Reassess during the flight. A plan made for 15 km of visibility does not hold in haze.

Detect and avoid

Detect and avoid means detecting traffic, deciding whether it is a threat, and acting in time. Below 400 ft the threat comes from medevac helicopters, agricultural aircraft and float planes. Many of them are non-cooperative: they carry no ADS-B Out, so an ADS-B In receiver will not see them. Listening on 126.7 MHz or the local aerodrome frequency helps, but does not replace a DAA solution.

The C2 link

• Know exactly what the RPA does when the link is lost: return home, hold, land or terminate.
• Set the return-to-home altitude above every ridge and obstacle on the route, while staying within 122 m AGL.
• Terrain and buildings block radio line of sight long before the advertised range. Place the control station on high ground.
• With latency at long range, avoid abrupt manual corrections.

Energy and terrain

Plan the return leg into the wind and keep a reserve for diversions. Check terrain along the whole route: over rising ground the RPA gets closer to obstacles, and over a valley it can climb above 122 m AGL without the display showing it.

Contingencies

• Choose emergency landing sites and termination areas along the route.
• Flight termination must not create a hazard to people or aviation.
• If the RPA flies away toward controlled airspace, notify the ATS unit immediately.
• Pre-arrange any handover between pilots, with a procedure for who has control.

Before sending the aircraft out of sight, fly a short check near the launch site to confirm control response, link quality and navigation.