OSO-06 — C2 Link

Properties
oso
6
title
C2 Link (C3 characteristics appropriate for the operation)
robustness
SAIL III (no L/M/H tag stated)
sail
III
doc_no
MOC to OSO#06-01
issue
1.0
issue_date
2024-12-19
status
Final
source_pdf
../../MoC to OSO#6.pdf
tags
['moc', 'oso', 'sora', 'sail-3', 'c2', 'c3', 'rf', 'brlos', 'rlos', 'link-budget']

OSO-06 — C2 Link

Source PDF

Summary

Compliance route for OSO#06 at SAIL III, focused on the Command and Control (C2) link between CMU and UA (the broader "C3" also covers any other communication link required for safety of flight). The applicant must substantiate two claims: (a) the C2 link performance is adequate for the intended operation under applicable environmental conditions, and (b) the remote pilot has continuous means to monitor C2 performance. Spectrum authorisation, ATC communications standards, and integrated U-space services are out of scope.

Operation Safety Objective

OSO#06 — C3 characteristics are appropriate for the operation. Performance, RF spectrum usage, and environmental conditions must be adequate; remote pilot must continuously monitor and ensure performance continues to meet operational requirements.

Means of Compliance — Two Fundamental Claims

Compliance Steps

Functions, high-level architecture, on-board vs ground segment, physical/logical components, interfaces, exchanged data, nominal/degraded modes, transitions, recovery/reacquisition, directional vs omnidirectional; physical installation; operational procedures; training-syllabus supplement; flight-manual configuration parameters; minimum network requirements for SLA with external service providers.

2. Determine minimum required performances (§3.2.1)

Across full operational range under expected operating conditions:

Dimension Requirement
Coverage Operational range as "design envelope"; max range first assessed by analysis (§3.2.2.1) and then confirmed by tests (§3.2.2.6). Multi-repeater relaying must operate in declared range. FTS/M2 actuation via C2 must be range-compatible.
Latency Maximum acceptable latency of overall command-and-control loop, accounting for automation level, contingency-action timing, and SORA Low (final ARC-b) TMPR latency.
Integrity Undetected-error rate sufficiently low not to jeopardise safety. CRC32 with Ethernet polynomial 0x04C11DB7 or equivalent unless lower acceptable demonstrated.
Functional performance C2 Link HW/SW must comply with OSO#05 and OSO#24 (refer to those MoCs).
Continuity & Availability SAIL III: no explicit min — adequately achieved by complying with §3.2.2.1 and §3.2.2.6.
Protection Comply with ASD-STAN prEN 4709-001 ("C2 Link protection", §6.7.2 in prEN at MoC publication date) or EUROCAE ED-325 Vol. 1 subpart H (Light-UAS.2730 "C2 Link security").

3. Demonstrate min performances (§3.2.2)

4. Operational and environmental limitations (§3.2.3)

Recorded in flight manual.

5. Continuous monitoring by remote pilot (§3.3)

6. Pre-flight checks (§3.4)

At least once per operational day before first flight; transmission test detecting connector/antenna degradation; ability to manually decrease transmit power recommended to simulate operational conditions.

7. Fresnel-radius obstruction (§3.5)

Applicant may declare design robustness vs. obstruction; quantify max obstruction in flight manual; analyse and test additional losses.

8. External services — LTE/SATCOM (§3.6)

  1. Identify type of external service.
  2. Substantiate evidence with service in the loop, define operational envelope and limitations.
  3. Identify minimum network requirements (latency, bit rate, bandwidth, max losses, power, sensitivity) so operator can establish SLA.
  4. Alternative: demonstrate UAS robustness to external-service failure (e.g. dual LTE providers, LTE+SATCOM redundancy with switching) — then OSO#13 SLA not strictly required.
  5. Specify all the above in flight manual.

9. Communications (§3.7)

ATC over VHF: latency must allow effective comms or impose range limits. Equipment integration at CMU/UA level checked. U-space comm performance defined per individual U-space airspace risk assessment (ARA); not assessed here.

Worked Example — SAIL III industrial linear-infrastructure surveillance (§4)

Op: gas-network linear inspection, RLOS to 60 km, <120 m AGL uncontrolled airspace (Arc-b), max 100 km/h, no/light precipitation, no HIRF. UAS: automatic flight throughout; pre-uploaded contingency/emergency trajectories; cooperative DAA with auto evasion; dual transmitter/receiver on UA & CMU; HD video downlink; auto return-to-home on C2 loss. Link budget: TX power 20 dBm, TX gain 18 dB, RX gain 10 dB, distance 60 km, 2400 MHz → received power ≈ −88 dBm. Tests per §3.2.2.6 confirm. Applicant determines C2 transaction time <0.5 s, more demanding than SORA TMPR Low ARC-b (5 s), but TMPR met by UA's automatic reaction (cooperative DAA), so C2 latency loop is independent of TMPR — checked outside C2 MoC scope.

Assumptions & Limitations

References