Bridge survey in airport surrounding airspace with a hidden far pier
A construction company will photograph a 90 m bridge for 12 minutes at 110 m AGL. The launch point is 1.5 km from the boundary of a local airport, inside its surrounding airspace but outside the airport's red zone; the site is not a DID. The bridge crosses a river, and the far pier is 250 m from the pilot and hidden behind the bridge deck for about 40 seconds. The company has a registered 4.5 kg quadcopter and plans to use a 2.4 GHz control link. They filed a flight plan through DIPS 2.0 and received an automatic receipt. The site manager says notification is enough because the flight is below 150 m and not over a DID. A visual observer will stand on the near bank, but the observer's view of the far pier is also blocked by the deck.
1. Which airspace and operational rules are triggered, and is the site manager correct that notification alone is enough?
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The site manager is only partly right. Because the launch point is inside the airport's surrounding airspace, the flight requires the applicable notification to MLIT for that airspace. At 110 m AGL the flight is below the 150 m threshold, and because the site is not a DID, those two specific-flight approvals are not triggered. However, the far pier is hidden from both pilot and observer for about 40 seconds, so the flight is effectively beyond visual line of sight for that segment. BVLOS requires specific-flight approval and a credible risk-mitigation method; a DIPS receipt is not that approval. The 2.4 GHz link also has to be considered against the bridge structure and river reflection, but the decisive issue is visibility, not radio frequency alone. The company cannot rely on the automatic receipt as authority to fly the hidden segment.
2. Can the visual observer on the near bank cure the visibility problem? Explain what would be needed.
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No. VLOS requires the pilot or a competent observer to see the aircraft continuously, not merely to know where it should be. The near-bank observer's view is blocked by the same deck that hides the aircraft from the pilot, so the 40-second segment remains BVLOS. A second observer on the far bank might restore visual contact, but only if that observer has clear sight, is in communication with the pilot, and the operating method is accepted in the approval. The company could instead reposition the aircraft so the far pier is not occluded, shorten the route, or apply for BVLOS approval with specific mitigations such as route limits, altitude, communications and abort criteria. Simply adding an observer who cannot see the aircraft does not satisfy the rule and would not make the DIPS receipt sufficient.
3. What should the pilot do before launch, and what records should be kept?
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Before launch the pilot should verify the airspace classification, complete the required notification, confirm whether any specific-flight approval is needed for the hidden segment, and check that the proposed observer positions actually provide continuous sight. The pilot should also confirm registration, Remote ID or direct marking, battery and link performance, and a clear abort plan if the aircraft disappears behind the deck. Records should include the airspace determination, notification/approval references, flight plan, risk assessment, observer positions, weather, pre-flight check, and any changes made on site. If the hidden segment cannot be approved or mitigated, the flight should be redesigned rather than launched on the strength of the DIPS receipt.