3.4 ATC Instructions, Clearances & Deconfliction

3.4 ATC Instructions, Clearances & Deconfliction

Quick Answer: In controlled airspace, Advanced RPAS operations are constrained by CAR 901.71 (operations under the applicable controlled-airspace conditions) and CAR 901.72 (comply with ATC instructions). Know the difference between a clearance (authorization to do something) and an instruction (direction you must follow), use proper readbacks, maintain see-and-avoid and give way to all crewed aircraft, and if limits or safety conflict—land or cease. Authorization never outranks collision avoidance.

Authorization gets you into the system. This section is about behaving correctly inside the system: listening, complying, deconflicting, and terminating the flight when the safe envelope disappears.

CAR 901.71 — Operations in Controlled Airspace

CAR 901.71 themes address conducting RPAS operations in controlled airspace in accordance with the conditions that apply to that flight. In practical Advanced language:

• You are in controlled airspace only because the regulatory conditions (certificate, aircraft declaration as required, written authorization, operating rules) are met.
• The authorization’s limits are part of the legal operating envelope.
• You remain responsible for Part IX general rules (VLOS, fitness, right of way, weather, etc.) even while authorized.

901.71 is the “you may operate here under conditions” companion to the authorization process in Section 3.3. On scenario questions, if a pilot has no authorization or flies outside authorization limits, they are not “kind of operating under 901.71”—they are outside the permitted framework.

CAR 901.72 — Comply with ATC Instructions

CAR 901.72 requires the pilot to comply with air traffic control instructions. Once you are a participant in controlled airspace operations—whether through a coordination arrangement specified in your authorization or through direct communication requirements—you do not get to negotiate safety instructions after the fact because the client wants one more take.

Compliance examples:

• ATC (or the unit specified in your procedures) directs you to land immediately or cease operations → land/cease.
• You are instructed to remain clear of a reopened approach path → reposition or shut down.
• You are told to switch frequency or contact a unit as required by the authorization procedures → do it without delay.

Non-compliance with ATC instructions in controlled airspace is not a customer-service issue; it is an aviation safety offence pathway.

Clearances vs Instructions

Use precise aviation language:

Pilots fail exams and field audits when they treat an advisory as a clearance, or treat a clearance/authorization limit as optional. If you need to climb above the authorized altitude, you need a new approval path—not creative reinterpretation of silence on the frequency.

Readbacks and Communication Discipline

When communication with ATC (or a designated unit) is required by your authorization or by the traffic situation:

• Use correct radiotelephony basics (covered in the radio chapter): listen first, transmit clearly, include who you are and where you are.
• Read back safety-critical items—altitude limits, landing instructions, hold-short/remain-clear instructions, frequency changes—so both sides share the same mental model.
• If you are unsure, ask for clarification before maneuvering into doubt.
• If you cannot comply (for example battery critical, lost link, or the instruction would cause an immediate greater hazard), communicate the problem and execute the safest available action, typically land/cease and make the aircraft safe.

Silence is not consent. Do not invent a clearance because ATC is busy.

Safety Overrides: When Authorization and Reality Conflict

Two envelopes must both be satisfied:

1. Regulatory/authorization envelope — class, written limits, certificate, declaration.
2. Safety envelope — traffic, weather, battery, link quality, VLOS, obstacle clearance.

If those envelopes conflict, safety wins by terminating or reducing the operation, not by expanding into unauthorized airspace or ignoring ATC. Examples:

• Traffic conflict develops inside your approved box → land or move only as authorized/instructed; give way to crewed aircraft.
• Wind increases and you cannot maintain VLOS inside the box → cease.
• ATC instructs immediate landing while you still have battery for “one more orbit” → land.
• Authorization altitude is too low for the obstacle you did not survey → you do not climb unauthorized; you replan.

See-and-Avoid and Right of Way

Authorization does not buy right of way. RPAS rules require drones to give way to all crewed aircraft. See-and-avoid remains continuous:

• Maintain visual contact with your RPA and the surrounding sky (use visual observers when appropriate and required by procedure).
• Expect helicopters and light aircraft at altitudes that look “drone-like.”
• If a crewed aircraft is inbound, descend/land/relocate as needed; do not hold position hoping they saw your 5-inch multirotor.
• Never manoeuvre toward an aircraft to “get the shot.”

Deconfliction is both procedural (authorization + ATC) and visual (see-and-avoid). Losing either layer is how mid-air risk is manufactured.

Authorize-Then-Fly Discipline Under Real-Time Pressure

Field pressure—clients, producers, inspectors on a timeline—pushes pilots to launch early or expand the box. Professional Advanced discipline is:

1. No written authorization covering the operation → no flight in controlled airspace.
2. Authorization received → brief limits to everyone on site.
3. ATC instruction received → comply.
4. Safety conflict → land/cease, then communicate.
5. Need a new altitude/time/location → new or amended authorization, not improvisation.

Loss of Link Near Controlled Airspace

Command-and-control lost-link near controlled airspace is a classic Advanced failure mode. If the RPA’s fail-safe climbs, returns along a path, or drifts on wind toward a control zone or final approach, you may create an unauthorized penetration or traffic conflict without any stick input.

Mitigations to build into site plans:

• Set maximum altitude and geofences that keep contingency paths outside controlled volumes when operating just outside a zone.
• Prefer fail-safes that land in place or return on a path remaining in Class G when that is the safety design for the site—test and understand the actual model behaviour.
• Brief observers to call traffic early.
• If link is lost and the aircraft may enter controlled airspace, follow your emergency procedures, attempt recovery, and be prepared to notify the appropriate ATS unit as required by the situation and your authorization conditions.

Lost-link planning is part of deconfliction, not an optional advanced tip.

Putting Chapter 3 Together

Master this chain and controlled-airspace questions become a workflow, not a bag of disconnected section numbers.