3.1 UK2/C2 Separation: 30 m Normal & 5 m Low-Speed Mode
Key Takeaways
- Under UAS.OPEN.030, a UK2 class-marked (or transitional EU C2) unmanned aircraft in A2 Near People operations must not overfly uninvolved persons and must keep a safe horizontal distance of at least 30 m in normal mode.
- The remote pilot may reduce horizontal separation to a minimum of 5 m only when the manufacturer’s active low-speed mode is engaged and after evaluating weather, aircraft performance, and segregation of the overflown area.
- Low-speed mode is an aircraft function that limits maximum speed (commonly about 3 m/s on class-marked types), cutting kinetic energy and shortening stopping distance—it is not a pilot estimate of flying “slowly.”
- Intentional overflight of uninvolved persons remains prohibited even when low-speed mode and the 5 m floor apply; the 5 m figure is a minimum horizontal buffer, not permission to fly over heads.
- Without a valid UK2 (or transitional C2) class mark, the pilot cannot claim the 30 m / 5 m UK2 separation privileges regardless of how light or slow the aircraft feels.
Why Separation Is the Core of A2 Theory
The A2 Certificate of Competency exists so remote pilots can operate in the Open category Near People subcategory with class-marked aircraft that are heavier or riskier than pure A1 Over People types. The privilege is not a free pass to fly close to the public. UAS.OPEN.030 and the CAA’s Near People guidance turn ground-risk control into measurable horizontal distances and a strict ban on intentional overflight of uninvolved persons—people who are not participating in the operation and have not accepted the risks.
For exam purposes, treat separation as a layered rule: (1) never intentionally overfly uninvolved persons; (2) keep at least the statutory horizontal floor that applies to your aircraft and mode; (3) add operational judgment (site selection, weather, performance, and the 1:1 height–distance practice covered later in this chapter) so a failure trajectory is unlikely to hit anyone. This section locks in the UK2 / transitional C2 floors: 30 m normal and 5 m with low-speed mode.
Who May Use the 30 m / 5 m Privileges
The reduced Near People distances are tied to class marking, not to how carefully you fly a random multirotor.
- UK2 class-marked unmanned aircraft (MTOM typically under 4 kg with the required safety features, including a selectable low-speed mode) operated by an A2 CofC holder under A2 rules.
- Transitional EU C2 aircraft treated as the corresponding UK2 mark during the UK transition window (EU C-class may be operated as the matching UK class until 31 December 2027; from 1 January 2028 they fall under legacy weight-based treatment—previewed in later chapters).
If the aircraft is legacy (no UK2/C2 class mark), even with an A2 CofC and MTOM under 2 kg, you use the 50 m legacy floor in the next section—not 30 m or 5 m. The exam loves scenarios where a pilot “feels” the drone is safe at 10 m without low-speed mode or without a class mark; the correct answer always follows the mark and the mode, not the pilot’s confidence.
Normal Operations: 30 m Horizontal Floor
In normal operations (low-speed mode not engaged), a UK2/C2 aircraft in A2 must maintain a safe horizontal distance of at least 30 metres from uninvolved persons. Horizontal means along the ground plane from the person to the aircraft’s position projected vertically—height does not “count as” part of the 30 m. Flying 40 m high directly over someone is still overflight and still fails the no-overfly rule, even if the vertical gap is large.
Safe horizontal distance is a regulatory phrase, not a suggestion. On the exam, if the stem says the aircraft is in normal mode (or does not mention low-speed mode), the minimum from uninvolved people is 30 m. Common distractors:
- 5 m — only with low-speed mode engaged after evaluation.
- 50 m — legacy A2 under 2 kg, or A3-style buffers, not UK2 normal mode.
- 150 m — typical A3 distance from residential, commercial, industrial or recreational areas, not the person-to-aircraft floor in A2.
Also remember the absolute rule that sits above every number: do not intentionally overfly uninvolved persons. The 30 m floor is the minimum sideways buffer when you are already staying clear of people; it does not authorise a flight path that passes over them at any height.
Low-Speed Mode: What It Means Exam-Wise
Low-speed mode is a manufacturer-provided aircraft function that actively limits maximum speed when the pilot selects it. On UK2/C2 class-marked types it is a design feature used to justify the reduced 5 m floor. Typical exam language describes it as capping speed around 3 m/s, which sharply reduces kinetic energy (energy scales with the square of speed) and shortens the stopping / braking distance if you must halt or reverse away from someone entering the area.
What low-speed mode is not:
- Not “I am flying gently on the sticks” without engaging the mode.
- Not a software speed limit you invent in a custom flight app on a non-class-marked airframe.
- Not the same thing as reducing height; height is a separate dimension and interacts with the 1:1 practice in Section 3.3.
- Not permission to overfly people more slowly.
For the A2 CofC theory paper, if a question asks why low-speed mode unlocks 5 m, the sound answer is about reduced kinetic energy and improved ability to stop or manoeuvre away, not about better camera quality or longer battery life.
Reducing to 5 m: Mode Plus Three Evaluations
The remote pilot may reduce the minimum horizontal distance to 5 m when both of the following are true:
- The active low-speed mode function is engaged on the unmanned aircraft.
- The pilot has evaluated:
- (1) weather conditions — wind, gusts, precipitation, visibility, and anything that could push the aircraft toward people or destroy the ability to hold position.
- (2) performance of the unmanned aircraft — mass/payload, battery state, control responsiveness, braking, GNSS hold quality, known limits in the manufacturer data.
- (3) segregation of the overflown area — whether the ground area under and near the flight path is effectively kept free of uninvolved persons (barriers, briefing of involved people, natural isolation, marshals, timing when the public is absent).
All three evaluations matter. Engaging low-speed mode in a crowded car park on a gusty day does not automatically make 5 m lawful or safe; the regulation couples the technical mode with pilot judgment of weather, performance, and segregation. On multi-part scenario questions, the correct choice often refuses 5 m when one of the three evaluations fails even though the mode is on.
After you step down to 5 m, the no intentional overflight rule still stands. Five metres is the minimum horizontal separation from uninvolved persons, not a vertical overflight clearance.
Mode → Minimum Horizontal Distance
| Operating condition (UK2 / transitional C2, A2 CofC, Near People) | Low-speed mode | Minimum horizontal distance from uninvolved persons | Intentional overflight of uninvolved persons |
|---|---|---|---|
| Normal operations | Off / not active | ≥ 30 m | Prohibited |
| Reduced separation (after weather, performance, segregation evaluation) | Active / engaged | ≥ 5 m | Prohibited |
| Low-speed mode claimed but evaluation skipped or conditions unsafe | Mode may be on, judgment fails | Treat as not entitled to 5 m; stay at ≥ 30 m or land / relocate | Prohibited |
| Aircraft lacks UK2/C2 class mark | N/A for privilege | Use legacy / subcategory rules (often 50 m—next section), not 30/5 | Prohibited |
Worked Scenarios (Exam Pattern)
Scenario A — Normal mode, clear site. You fly a UK2 multirotor at 25 m AGL for a roof survey. Uninvolved walkers are on a public path 35 m from the aircraft horizontally. Low-speed mode is off. This meets the 30 m floor if you stay at ≥30 m and never overfly them. If they move closer to 20 m, you must climb out laterally, reposition, or land—not continue because “they are only walking.”
Scenario B — Low-speed engaged, good evaluation. Same aircraft, low-speed mode on, light wind well inside manufacturer limits, full battery, strong GNSS hold, and the garden is fenced with only involved property staff briefed. You may operate down to 5 m horizontal from uninvolved persons outside the segregated plot, still without overflying them. If a delivery courier enters the plot, they are uninvolved until briefed and accepting risk—treat them as uninvolved and restore separation.
Scenario C — Mode on, evaluation fails. Low-speed mode is on but a 20 kt gusting wind is near the aircraft’s limit and the street cannot be segregated. The exam answer is not to rely on 5 m; maintain a much larger buffer, postpone, or move to an A3-suitable site. Mode alone never completes the privilege.
Scenario D — Confusing 3 m/s with 5 m. A question option states that low-speed mode allows 3 m separation because the speed limit is 3 m/s. Wrong: 3 m/s is a typical speed cap; 5 m is the distance floor. Memorise both and keep them in different mental buckets.
How This Links to the Rest of Ground Risk
Separation numbers are the statutory skeleton. Chapter 4 expands the evaluation into site selection, reacting to approaching people, and the formal weather–performance–segregation checklist before 5 m work. Chapter 5 connects low-speed mode to kinetic energy maths and technical mitigations (prop guards, parachutes, geo-awareness). For now, lock three exam sentences:
- UK2/C2 A2 normal → ≥30 m horizontal, no overflight.
- UK2/C2 A2 with active low-speed mode and weather + performance + segregation evaluation → ≥5 m horizontal, still no overflight.
- Low-speed mode means the manufacturer function that limits speed and energy—not informal slow flying.
If a stem never mentions class mark or mode, do not invent the 5 m privilege. If it mentions A3 or built-up area buffers, do not substitute 150 m for the person-distance question unless the stem is actually about A3 area rules. Read every stem for mark, mode, and who is uninvolved before you pick a number.
An A2 CofC holder is flying a UK2 class-marked drone in normal flight mode near a public footpath. What is the minimum permitted horizontal distance from uninvolved persons?
When may an A2 remote pilot reduce horizontal separation from uninvolved persons to a minimum of 5 m with a UK2 or transitional C2 aircraft?
For A2 theory purposes, what does engaging low-speed mode on a UK2 class-marked drone primarily achieve?
A pilot engages low-speed mode on a UK2 drone but faces gusty wind near the aircraft’s limit and cannot keep the street free of passers-by. Which action best matches the A2 separation rules?