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The trade · Use case

The last reconnaissance with a small drone

Before the flight with the big drone, a drone under 250 grams goes round the area. At low risk you see cables, obstacles, people, wind at height and signal. That flight is an operation too, with its own rules.

Sources checked on 13 October 2026

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Scenario

An inspection or a survey with a medium or large drone. The flight plan was prepared at the desk, but from the ground you cannot see everything: cables between poles, antennas on the roof next door, a crane put up yesterday, branches above the take-off point. Before the big drone takes off, a drone under 250 g is flown.

Objective

To see from above, at low risk, what the big drone will meet, and to correct the plan before the real take-off.

Risks

  • Obstacles not seen from the ground: cables, guy wires, antennas, cranes, trees.
  • People who walk into the area during the job.
  • Wind at height different from the wind on the ground.
  • Weak signal behind buildings or slopes.
  • Two drones in the air at the same time.

Category

The small drone. A privately built drone under 250 g, or a class C0 drone, flies in subcategory A1 of the 'open' category. The remote pilot may overfly uninvolved persons, "but shall never overfly assemblies of people" (Implementing Regulation (EU) 2019/947, Annex, UAS.OPEN.020(2)). The drone stays within 120 metres of the surface (Article 4(1)(e)) and in the pilot's sight (Article 4(1)(d)). Class C0 is defined in Delegated Regulation (EU) 2019/945, Annex, Part 1: "an MTOM of less than 250 g, including payload".

Zones apply to it too. Before the flight the remote pilot must have the information on geographical zones (UAS.OPEN.060(1)(b)) and during the flight must comply with their limitations (point (2)(c)).

If it has a camera, the operator registers. The obligation applies under 250 g as well, for an unmanned aircraft "equipped with a sensor able to capture personal data", except toys that comply with Directive 2009/48/EC (Article 14(5)(a)(ii)).

One drone at a time. In the open category EASA states that the remote pilot "should […] operate only one UA at a time" (AMC1 UAS.OPEN.060(2)(d)). In the standard scenarios it is the regulation itself: the remote pilot shall "operate only one unmanned aircraft at a time" (UAS.STS-01.040(2)(d); UAS.STS-02.040(2)(c)). So either the small drone lands before the big one takes off, or a second person flies it.

The main flight stays in its own category. If it is a 'specific' operation, the declaration or the authorisation states what is covered: if the reconnaissance takes place in the area while the big drone is flying, it has to be checked there.

Equipment

  • A drone under 250 g with a camera, batteries charged.
  • The big drone's flight plan, to compare with what you see.
  • If the reconnaissance is done while the other drone is in the air: a second pilot and a clear way to talk to each other.

Recommended sequence

  1. At the desk: zones, temporary restrictions and the big drone's flight plan.
  2. On site: a walk round on foot. The small drone does not replace it.
  3. Flight of the small drone along the big drone's route, at working height: cables, antennas, cranes, trees, people, access points, a spot for an emergency landing. Watch how much it drifts in the wind and how the signal holds.
  4. Landing. Note what you saw and keep the photos and video.
  5. If needed, correct the plan.
  6. Take-off of the big drone.

Common mistakes

  • The same pilot with two drones in the air.
  • Skipping the walk round "because the drone will see it anyway".
  • Forgetting that zones apply under 250 g as well.
  • Deleting the reconnaissance images: they are the proof of what was known before take-off.
  • Flying over a group of people because "the drone is small".

What to deliver

Usually nothing to the client. The reconnaissance images can go into the report as "site conditions at the time of the work".

What evidence to keep

  • Photos and video of the reconnaissance, with date, time and position.
  • The notes on what was seen and what was changed in the plan.
  • The flight in the logbook. In the 'specific' category the record of operations is an obligation of the UAS operator, to be kept "for a minimum of 3 years" (UAS.SPEC.050(1)(g)(iii)). In the open category the European rules do not require a logbook: recording the flight lets you prove that the check took place.

How it works in Dronetrake

  • The Mission Gate reads the flight plan (DJI KMZ or .plan) and checks it before take-off: UAS geographical zones, temporary restrictions and NOTAMs, authorised height, distance from the terrain.
  • The pre-flight checklist is filled in within the mission and stays signed.
  • The small drone's flight goes into the logbook like the others, with its own drone and its own pilot.
  • Photos and video of the reconnaissance are uploaded to the mission: every file has its fingerprint and its upload time.

Sources

The rules cited were read at the source on the date shown. The official text prevails. This chapter is information, not legal advice.

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