Night Flight Over Unfamiliar Terrain
You are conducting a night-time aerial survey with a small unmanned aircraft (sUAS) to map a 200-acre construction site. The site is in Class G airspace, and you have a valid Part 107 certificate with night operations. The sUAS is equipped with anti-collision lighting visible for 3 statute miles. The mission requires flying at 300 feet AGL to capture high-resolution imagery. The weather forecast predicts clear skies with a 10% chance of fog after midnight. Your visual observer (VO) reports that the anti-collision lights are functioning but are not visible from the far side of the site due to terrain. You have been flying for 45 minutes and the battery is at 30%. The sUAS is 0.5 miles from the launch point. The site has active construction equipment parked but no workers present. There is a nearby residential area 0.25 miles to the east. You notice that the sUAS's GPS signal is intermittently weak, possibly due to tall trees on the west side.
1. What are the key risk factors in this scenario, and how should you prioritize them according to the IMSAFE checklist?
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Key risk factors include: night conditions reducing visibility, potential fog, anti-collision lights not visible from all angles, low battery (30%), weak GPS signal, proximity to residential area, and terrain masking. Prioritize using IMSAFE: Illness (none reported), Medication (none reported), Stress (mission pressure to complete survey), Alcohol (none), Fatigue (45 minutes into flight, possibly fatigued), Emotion (complacency). The most immediate risks are battery life and GPS reliability. The pilot should consider terminating the flight early due to battery and GPS issues, and ensure the anti-collision lights meet the 3 SM visibility requirement; if not, operations must be adjusted or discontinued.
2. How should you adjust your flight operations to mitigate the risks identified, and what regulatory considerations apply?
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Mitigations: 1) Reduce altitude to maintain visual line of sight (VLOS) and ensure anti-collision lights are visible; 2) Shorten the flight to return before battery drops below 20%; 3) Use a secondary VO on the far side to maintain visibility; 4) Monitor GPS signal and be prepared to switch to manual control; 5) Check weather updates for fog. Regulatory: Part 107 requires VLOS at all times (107.31), anti-collision lighting visible for 3 SM (107.29), and no flight over people (107.39). The residential area is not directly overflown, but caution is needed. If GPS is unreliable, the pilot must ensure the sUAS can be controlled safely without GPS. The pilot should also consider the waiver requirements if operating beyond visual line of sight, but here VLOS is maintained.