Detailed working notes on the provision of aerodrome air traffic services from a remote location via camera arrays, sensor systems, and data links. This folder expands the summary in topics/remote_tower.md into per-aspect files for deeper reading.

Files in this folder#

• overview.md — what remote towers are, where they sit in the ICAO/EASA regulatory and ASBU framework, and the three deployment models.
• components.md — the building blocks of a remote tower system: sensor array, data link, remote tower module, CWP, recording.
• blocks.md — the deployment model progression from single remote tower through contingency to multiple remote tower centre, mapped to ASBU RATS block stages.
• threads.md — functional axes of the RATS thread: visual reproduction, surveillance integration, HMI/human factors, safety case, contingency, multiple-aerodrome operations.
• modules.md — anatomy of a single-aerodrome remote tower service and a multiple remote tower operation, with a safety case worked example.
• enablers.md — CNS, procedures, training, regulation, and institutional prerequisites.
• performance_objectives.md — KPAs, KPIs, and performance frameworks relevant to remote tower deployments.
• timeline.md — historical evolution from early trials (2011-2012) to the first operational remote tower (2015) and current regulatory status.
• references.md — consolidated ICAO and authoritative external references for this folder.

Reading order#

Start with overview.md, then components.md, then blocks.md and threads.md. Read modules.md for worked examples. Use enablers.md for the dependency chain and performance_objectives.md for the KPA/KPI framework. timeline.md gives date context and references.md consolidates all citations.

Source basis#

Content is grounded in:

• ICAO Doc 4444 (PANS-ATM), Chapter 7, §7.1.1.2.1 and §7.12.
• ICAO Annex 11 (Air Traffic Services), Chapters 2, 3, and 6.
• ICAO Annex 14 Volume I, Chapter 5, §5.1.3.
• ICAO Doc 10007 (AN-Conf/12 Report, 2012), Module B1-RATS.
• ICAO Doc 10071 (Assembly A-39 Report, 2016), §35.33.
• ICAO Doc 10209 (AN-Conf/14 Report, 2022), §3.20.
• EASA ED Decision 2019/003/R (AMC/GM to (EU) 2017/373).
• SESAR 3 JU / Digital European Sky remote tower solutions.

What remote towers are#

A remote tower (also called a remotely operated aerodrome tower or digital tower) is a system by which aerodrome air traffic services are provided from a facility not physically located at the aerodrome. A controller working at a remote tower module (RTM) observes the aerodrome scene via a high-fidelity electronic reproduction — delivered by a camera and sensor array installed at the physical aerodrome — rather than through glass tower windows.

The concept does not alter the services provided to airspace users. It changes how those services are delivered, through new technologies and working methods. From the pilot's perspective, the communication channel, the clearances received, and the coordination procedures remain identical to those at a traditionally-staffed local tower.

ICAO normative basis#

PANS-ATM (Doc 4444) Chapter 7, section 7.1.1.2.1 states:

Visual observation shall be achieved through direct out-of-the-window observation, or through indirect observation utilizing a visual surveillance system which is specifically approved for the purpose by the appropriate ATS authority.

The accompanying PANS-ATM definition (Chapter 1) establishes:

Visual surveillance system — an electro-optical system providing an electronic visual presentation of traffic and any other information necessary to maintain situational awareness at an aerodrome and its vicinity.

Section 7.12 of PANS-ATM then specifies the conditions under which a visual surveillance system may be used in aerodrome control service. These two provisions form the normative foundation for all remote and digital tower operations under ICAO standards.

Where remote towers sit in the ATM framework#

Remote and digital towers occupy three positions simultaneously:

1. A regulatory concept under Annex 11 and PANS-ATM. Annex 11 requires aerodrome control service to be provided by an aerodrome control tower but does not require the controller to be physically present at the aerodrome. PANS-ATM Chapter 7 provides the procedural framework, including the permission for indirect visual observation.

2. Module B1-RATS in the ASBU framework. The ICAO ASBU thread RATS (Remote Air Traffic Services) — introduced in the AN-Conf/12 report (Doc 10007, 2012) — is the planning mechanism that positions remote towers within the global ATM modernization roadmap. RATS sits under Performance Improvement Area 1 (Airport Operations). Block 1 covers initial operational remote towers (single and contingency); Block 3 extends to fully remote and virtual aerodrome control services.

3. An emerging regulatory domain under EASA. In European airspace, EASA ED Decision 2019/003/R introduced AMC/GM to Commission Implementing Regulation (EU) 2017/373 that provide specific guidance material for remote aerodrome ATS. AN-Conf/14 (2022, Doc 10209) called on ICAO to continue developing SARPs and guidance for digital air traffic services for aerodromes (DATS) and remote towers, including cybersecurity and cross-border aspects.

The three deployment models#

A remote tower centre (RTC) is the facility housing the RTMs. It may be co-located with an existing ACC or ATCC, or be a standalone building. The RTC may operate a mix of single and multiple modes simultaneously.

Why remote towers matter#

Three converging pressures drive remote tower adoption:

Economic viability at small aerodromes. Many regional aerodromes cannot sustain the cost of a full tower building, staff, and maintenance. Remote towers — especially in multiple-aerodrome mode — allow centralised staffing pools, shared training, and standardised systems, reducing per-aerodrome operating costs. Doc 10007 Module B1-RATS notes cost-benefit assessments showing staff cost reductions of 10 to 35 percent depending on scenario.

Contingency resilience. Large and medium aerodromes need a contingency fallback when the primary tower is unavailable. A remote tower eliminates the need for a separate physical backup tower at the aerodrome.

Capability enhancement. Digital enhancement of the visual scene (graphical overlays of aircraft positions, weather data, lighting status, infrared for low-visibility) can in principle provide better situational awareness than a controller at a physical tower window in poor visibility, fog, or night conditions.

Relationship to other topics#

• ASBU — RATS is a thread under ASBU PIA-1; Block 1 and Block 3 modules define the remote tower implementation roadmap.
• A-CDM — multiple remote tower operations generate additional CDM data (slot coordination, demand balancing across the cluster).
• SWIM — system-wide information sharing supports the integration of position data, meteorological data, and flight plan data in the RTM display.
• Airspace management — extending service hours at small aerodromes through remote towers has airspace classification and FIR-level service provision implications.
• ILS categories — a remote tower may support CAT II/III operations at the served aerodrome if the visual surveillance system is certified for that role; low visibility procedures (Doc 4444 §7.13) remain applicable.

References#

• Doc 4444 (PANS-ATM), Chapter 1 — definition of "Visual surveillance system".
• Doc 4444 (PANS-ATM), Chapter 7, §7.1.1.2.1 — normative permission for indirect visual observation via an approved visual surveillance system.
• Doc 4444 (PANS-ATM), Chapter 7, §7.12 — capabilities, reliability requirements, and functions of visual surveillance systems in aerodrome control service.
• Annex 11 (Air Traffic Services), Chapter 2 and Chapter 3 — aerodrome control service definition and provision requirements.
• Doc 10007 (AN-Conf/12 Report, 2012), Module B1-RATS, §1.1 — definition of remotely operated aerodrome control and its three operational elements.
• Doc 10007, §2.1.3 — AN-Conf/12 endorsement and extension of the RATS module to the full spectrum of remote ATS.
• Doc 10209 (AN-Conf/14 Report, 2022), §3.20 — call for continued ICAO provisions for DATS and remote towers.
• EASA ED Decision 2019/003/R — AMC/GM to (EU) 2017/373, remote aerodrome air traffic services guidance (authoritative source — not in local library).

A remote tower system is not a single product. It is a structured set of interlocking sub-systems that together reproduce the situational awareness of a local aerodrome tower at a remote location. The components are:

1. Visual information capture — camera array#

The camera array is the sensory foundation of the remote tower. It acquires the out-the-window (OTW) view that the remote controller must receive.

Sub-components:

• Fixed wide-angle cameras — provide a continuous, full-perimeter view of the aerodrome circuit and manoeuvring area. Typically distributed around the aerodrome to eliminate blind spots.
• Pan-tilt-zoom (PTZ) cameras — allow the controller (or automation) to direct a high-magnification view to a specific area of interest: an aircraft on final approach, a vehicle crossing the apron, or a runway surface detail.
• Infrared / thermal cameras — provide a usable image in darkness and reduced visibility conditions where visible-spectrum cameras alone are insufficient. Enhance the remote tower's performance over a local tower at night.
• Camera mounting mast(s) — the physical equivalent of the tower building. One or more masts at the aerodrome at heights sufficient to replicate or improve on the line-of-sight achieved from a conventional tower cab.

The visual reproduction shall enable visual surveillance of the airport surface and surrounding area (Doc 10007 Module B1-RATS, §1.1.5). Multiple viewpoints from different mast positions can provide enhanced situational awareness compared to the single fixed viewpoint of a conventional tower cab.

2. Additional sensors and data overlays#

The visual picture is augmented with data from non-visual sensors:

• ADS-B receivers or multilateration (MLAT) — provide position tracks of aircraft and equipped vehicles, displayed as graphical overlays on the visual scene. The controller sees both the camera picture and a labelled track for each target.
• Surface movement radar (SMR) / A-SMGCS — for larger aerodromes and low-visibility operations, radar or multilateration ensures surface situational awareness does not depend solely on the camera.
• Meteorological sensors — RVR sensors, wind sensors (anemometers at multiple runway positions), cloud base sensors, barometric pressure sensors. Readings are displayed in the RTM in real time. The same sensor suite feeds the RTM as feeds a local tower (per Annex 11 §7.1.4 requirements).
• Lighting status monitoring — real-time feedback on runway edge lights, approach lights, taxiway lights, and stop bars. The controller needs confirmation that lights activated at the RTM have actually energised at the aerodrome.
• Runway surface sensors — friction/contamination sensors at some installations supplement the visual scene with pavement state data.

3. Remote tower module (RTM) and controller working position (CWP)#

The RTM is the controller's workplace at the remote location. It is the equivalent of the tower cab, realised as a suite of displays and interfaces.

Components of the RTM/CWP:

• Panoramic display system — typically a curved or wraparound screen arrangement reproducing the full 360-degree view of the aerodrome, or a subset appropriate to the aerodrome geometry. May use high-definition screens, projectors, or a combination. Latency must be low enough to be imperceptible to the controller (typically under 300 ms end-to-end for the visual stream).
• Graphical overlay workstation — displays the surveillance, meteorological, and flight plan data overlaid on or adjacent to the visual scene. Labels, tracks, and alert indications are rendered here.
• PTZ control interface — joystick or touch control allowing the controller to direct pan-tilt-zoom cameras.
• Radio communication panel — voice radio stack providing the aerodrome TWR frequency and ground frequency, identical in functionality to a local tower radio panel.
• Lighting control panel — remote actuation of aerodrome lighting (approach, runway, taxiway, stop bars).
• ATIS update and transmission interface — allowing D-ATIS updates from the remote location.
• Strip or electronic flight data display — flight progress strips or electronic equivalent, as applicable.
• Intercom and ground-to-ground communications — for coordination with approach control, adjacent sectors, aerodrome operations, and emergency services.

The PANS-ATM §7.12.1.2 requirement that the visual surveillance system shall receive, process, and display data from all connected resources in an integrated manner drives the RTM design toward a single, unified display environment rather than fragmented screens.

4. Remotely operable signal light (light gun)#

Annex 14 Volume I, section 5.1.3.1 requires that a signalling lamp shall be provided at a controlled aerodrome in the aerodrome control tower. In a remote tower deployment, the physical signalling lamp must remain at the aerodrome (since pilots must be able to receive its signals), but it must be operable by the remote controller.

This is achieved through a remotely operable signal light unit at the aerodrome connected to the RTM via the data link, with a pointing and activation interface at the CWP.

5. Data link infrastructure#

The data link carries the video streams, sensor data, control commands, and coordination communications between the aerodrome and the remote tower centre.

Requirements:

• Bandwidth — sufficient for multiple high-definition video streams simultaneously (camera array, infrared, surface radar).
• Latency — low and stable; high latency in the video stream degrades controller situational awareness.
• Redundancy — PANS-ATM §7.12.1.1 requires that system failures shall be assessed and backup facilities or alternative operational procedures provided. The data link is a critical single point of failure and must have a redundant path.
• Security — communications between aerodrome and RTC must be protected against interference, spoofing, and intrusion; noted as a requirement by AN-Conf/14 (Doc 10209 §3.20).

6. Recording systems#

PANS-ATM §7.12.1.1 requires visual surveillance systems to have appropriate reliability, availability, and integrity. The note at §7.1.1.2.1 references Annex 11 §6.4.1 for automatic recording of visual surveillance system data. Annex 11 §6.4.1.2 requires surveillance recordings to be retained for at least thirty days.

In practice, a remote tower system must record:

• The video streams from all cameras (continuous).
• Controller voice communications (per Annex 11 §6.1.1.3).
• All control commands issued from the RTM (lights, signals).
• Meteorological data time series.

7. Remote tower centre (RTC)#

The RTC is the facility housing the RTMs. It may:

• Be a standalone building remote from any aerodrome.
• Be co-located with an existing area control centre or approach control unit, sharing facilities and staff pools.
• Contain a mix of single remote tower modules and multiple remote tower modules.

Module B1-RATS (Doc 10007 §1.4.3) describes the RTC as containing several remote tower modules, similar to sector positions in an ATCC. Each RTM is connected to at least one aerodrome and contains one or more CWPs depending on the size and traffic of the connected aerodrome.

Component hierarchy#

The nested relationship of components can be summarised as:

• Remote tower centre (RTC)

  • Remote tower module (RTM) — per aerodrome served
    • Controller working position (CWP)
    • Panoramic display system
    • Graphical overlay workstation
    • Radio and communications panel
    • Lighting and signal control
  • Shared facilities: staff areas, training simulators, maintenance

• Aerodrome local installation

  • Camera mast(s) and camera array
  • Sensor suite (MLAT/ADS-B, met, SMR)
  • Remotely operable signal light
  • Data link termination equipment
  • Local power and backup power

References#

• Doc 4444 (PANS-ATM), Chapter 7, §7.1.1.2.1 — visual observation by indirect means via approved visual surveillance system.
• Doc 4444 (PANS-ATM), Chapter 7, §7.12.1.1 — reliability, availability, integrity requirements and backup requirements for visual surveillance systems.
• Doc 4444 (PANS-ATM), Chapter 7, §7.12.1.2 — visual surveillance systems shall receive, process, and display data from all connected resources in an integrated manner.
• Annex 11, Chapter 6, §6.1.1.3 — automatic recording of voice communications in ATC.
• Annex 11, Chapter 6, §6.4.1 — automatic recording of surveillance data; retention for thirty days minimum.
• Annex 14 Volume I, Chapter 5, §5.1.3.1 — signalling lamp requirement at controlled aerodrome.
• Doc 10007 (AN-Conf/12 Report, 2012), Module B1-RATS, §1.1.4 — visual information capture and reproduction with data overlay for the remote ATCO.
• Doc 10007, Module B1-RATS, §1.4.3 — structure of the remote tower centre and its modules.
• Doc 10007, Module B1-RATS, §4.1.1 and §4.1.2 — camera-based solutions, situational awareness, sensor placement, and graphical overlays.
• Doc 10209 (AN-Conf/14 Report, 2022), §3.20 — cybersecurity as a required consideration in remote tower data link and system design.

How deployment models map to ASBU blocks#

The RATS thread (Remote Air Traffic Services) uses the ASBU block structure to describe a progression of deployment capability. Each stage builds on its predecessor: single remote tower experience enables the safety case methodology for multiple remote tower; contingency tower capability enables resilience for larger aerodromes.

Stage 1 — Contingency tower (baseline)#

What it is. A remote or virtual facility used only when the primary local tower is unavailable. The controller observes a reproduced or radar-based view of the aerodrome rather than the direct OTW view.

Target. Medium and large aerodromes with an obligation to maintain service continuity. European SES contingency obligation (Regulation (EU) 2017/373 §8.2: an ANSP shall have contingency plans in cases of significant service degradation) drives this.

Limitations. Early contingency facilities (pre-2012) used A-SMGCS or camera feeds without the full 360-degree panoramic display; they are the precursor of the OTW remote tower. Doc 10007 §1.3.2 cites the London Heathrow virtual contingency facility as an early example.

Stage 2 — Single remote tower (B1-RATS)#

What it is. Full remote provision of ATS (either TWR or AFIS) for one aerodrome from one remote tower module at an RTC. The local tower building may be decommissioned.

Target. Small or medium aerodromes where maintaining a staffed local tower is economically unviable but where aviation provides local economic and social benefit (Doc 10007 Module B1-RATS, summary para.).

Operational model. One ATCO or AFISO at the RTC serves the aerodrome. The RTC may contain multiple single-tower modules, each serving a different aerodrome, with separate controllers at each.

First operational example. Ornskoldsvik aerodrome (Sweden), served from Sundsvall by LFV — the world's first operational remote tower, becoming fully operational in 2015 (authoritative source — not in local library).

Regulatory readiness estimate. Doc 10007 (2012) estimated standards readiness circa 2018. EASA ED Decision 2019/003/R confirmed European regulatory readiness for single mode.

Stage 3 — Multiple remote tower (B1-RATS extended)#

What it is. One ATCO or AFISO providing ATS to more than one aerodrome simultaneously from a single RTC, switching attention between aerodrome modules as traffic demands.

Target. Groups of small or medium aerodromes with low or non-overlapping traffic patterns. The clustering of aerodromes (which aerodromes can be served in parallel) is a critical design decision.

Operational factors (from Doc 10007 §1.5.3):

• Resource management — shift size versus number of aerodromes and traffic demand.
• CWP configuration — one CWP may serve one aerodrome, several aerodromes, or share service with another CWP (larger aerodromes).
• Operating methods — when no traffic is present, one ATCO can monitor more aerodromes; as demand rises, the served count reduces.
• ATM — slot coordination and traffic synchronisation across the multiple aerodromes to reduce simultaneous-movement events.
• Aerodrome clustering — the selection algorithm for which aerodromes can be grouped.
• Approach control integration — whether approach control is also provided by the multiple-aerodrome ATCO or by a separate APP controller.

Regulatory status. EASA ED Decision 2019/003/R includes guidance for multiple remote tower mode. The EASA framework distinguishes single mode and multiple mode operations with different competency and approval requirements (authoritative source — not in local library).

Stage 4 — Remote tower centre at scale (RATS-B3)#

What it is. The Block 3 vision: fully remote and virtual aerodrome control services across a mature regional cluster, with automation assistance for demand prediction, alerting, and mode switching.

Target. A region in which most or all small and medium aerodromes are served from one or two RTCs, with only the largest aerodromes retaining local towers.

Dependencies. RATS-B3 depends on mature regulation, validated automation-assisted multiple-mode operations, cybersecurity frameworks, and cross-border recognition of remote tower approvals. AN-Conf/14 (2022) noted these as areas still under development.

Block dependency note#

The ASBU blocks.md exemplar lists:

• B1-RATS in Block 1 (notional from 2019): "Remotely operated aerodrome control tower contingency and remote provision of ATS to aerodromes through visualisation systems and tools."
• RATS-B3 in Block 3 (notional from 2031): "fully remote and virtual aerodrome control services."

There is no RATS module in Block 0 or Block 2 in the current GANP Portal taxonomy because the baseline (contingency) is a pre-Block 1 capability and the Block 2 period covers consolidation and expansion of the Block 1 deployments rather than a distinct new capability step.

References#

• Doc 10007 (AN-Conf/12 Report, 2012), Module B1-RATS, §1.1.2 — three elements of remotely operated aerodrome control: single aerodrome, multiple aerodromes, and contingency.
• Doc 10007, Module B1-RATS, §1.4 through §1.6 — operational descriptions of the three elements.
• Doc 10007, Module B1-RATS, §1.5.3 — factors specific to multiple aerodrome remote tower operations.
• Doc 10007, §1.3.1 — single tower services expected as baseline for multiple tower services.
• Doc 10209 (AN-Conf/14 Report, 2022), §3.20 — ongoing ICAO work on DATS and remote tower provisions.
• EASA ED Decision 2019/003/R — single mode and multiple mode AMC/GM under (EU) 2017/373 (authoritative source — not in local library).

The RATS thread in the ASBU framework is itself composed of several functional axes. Each axis represents a domain of technical, operational, or regulatory challenge that must be solved for remote tower operations to succeed. Understanding these axes helps planners sequence work and identify where gaps lie.

Axis 1 — Visual reproduction and scene quality#

What it covers. The fidelity, coverage, and latency of the reproduced aerodrome visual scene at the remote tower module.

Key questions.

• Does the camera array provide unobstructed sight lines to all operationally relevant parts of the manoeuvring area and circuit?
• Is the panoramic display system geometry and resolution sufficient for the controller to accurately judge aircraft position, taxi compliance, runway occupancy, and circuit spacing?
• Is end-to-end latency in the video stream low enough that the controller's situational awareness is not degraded?
• Do infrared cameras provide usable night / low-visibility images?

Standards link. PANS-ATM §7.12.1.1 (reliability and integrity of the visual surveillance system) and §7.1.1.5 (requirement for appropriate situational awareness) frame this axis. PANS-ATM §7.1.1.2.1 requires that the visual surveillance system is specifically approved by the ATS authority.

SESAR delivery. SESAR 3 JU / Digital European Sky remote tower solutions include human factors validation trials assessing display geometry, resolution thresholds, and controller task performance (authoritative source — not in local library).

Axis 2 — Surveillance integration#

What it covers. The overlay of radar, ADS-B, multilateration, and surface movement data on the visual scene to supplement what cameras can show, particularly in reduced visibility.

Key questions.

• Are aircraft and vehicle positions accurately fused with the panoramic display?
• Does the surveillance overlay reduce or introduce false situational awareness (clutter, missed targets)?
• What is the fallback procedure when the surveillance overlay fails but the visual stream remains usable?

Standards link. PANS-ATM §7.12.1.2 requires integrated display of data from all connected resources. Section 8.10 (use of ATS surveillance systems in aerodrome control service) provides procedural constraints on surveillance integration.

Dependency. For the multiple remote tower and contingency tower modes at larger aerodromes, A-SMGCS or equivalent surface surveillance is a prerequisite (noted in Doc 10007 §1.6.2).

Axis 3 — Human factors and HMI#

What it covers. The human-machine interface design of the remote tower module; the cognitive and workload implications of operating via a display rather than a window; and multi-aerodrome task management in the multiple remote tower mode.

Key questions.

• Does the RTM HMI replicate the spatial awareness cues (depth perception, peripheral vision, head movement parallax) that a controller has at a physical tower?
• How does the controller manage attention across aerodromes in the multiple mode?
• What are the workload limits for the number of aerodromes per controller per hour?
• How is fatigue managed when the visual scene is reproduced electronically rather than observed directly?

Standards link. ICAO Assembly A-39 (Doc 10071 §35.33) directed that any ICAO regulation take human factors principles into account. Module B1-RATS (Doc 10007 §5.1.1) identifies HMI and automation human-machine interface as important enablers with associated risk mitigation strategies (training, redundancy).

Regulatory link. EASA ED Decision 2019/003/R specifies competency requirements that differ between single mode and multiple mode, reflecting the additional cognitive demands of the latter (authoritative source — not in local library).

Axis 4 — Safety case#

What it covers. The formal, aerodrome-specific safety assessment that demonstrates remote tower operations are at least as safe as the displaced local tower service.

Key questions.

• What failure modes exist (camera loss, data link outage, display failure) and what are their likelihoods and safety consequences?
• What backup or fallback procedures reduce risk to acceptable levels?
• How is the safety case structured: hazard identification, risk assessment, safety requirements, verification?
• Is the safety case approach common across multiple aerodromes in a cluster, or aerodrome-specific?

Standards link. PANS-ATM §2.6.1.1 requires a safety risk assessment for proposals for significant changes in the provision of ATS procedures or the introduction of new equipment, systems, or facilities. The transition from a local tower to a remote tower is a significant change requiring a formal assessment. PANS-ATM §7.12.1.1 specifies that the possibility of system failures shall be assessed and that there shall be no degradation in the safety level of services rendered.

ICAO guidance. Doc 9854 (Global ATM Operational Concept) and the Safety Management Manual (Doc 9859) provide the methodology framework for the safety case.

Axis 5 — Contingency procedures#

What it covers. The procedures that apply when the remote tower system experiences full or partial failure.

Key questions.

• What happens if the data link between the aerodrome and RTC fails?
• What happens if the visual stream is lost but surveillance and communications remain?
• What is the minimum service that can be maintained, and for how long?
• Who is responsible for physical aerodrome tasks (runway inspection, vehicle management) when the ATC function is suspended?

Standards link. PANS-ATM §7.12.1.1 requires backup facilities or alternative operational procedures. Doc 10007 §3.3 and §3.4 address contingency: full failure results in suspension of ATS until partial restoration; partial failure (e.g., loss of visual stream) can be mapped to existing low-visibility procedures.

The European SES contingency obligation (referenced in Doc 10007 §1.6.3) requires an ANSP to have contingency plans for significant service degradation.

Axis 6 — Multiple-aerodrome operations#

What it covers. The operational concepts, demand management, and staffing models unique to one controller serving several aerodromes.

Key questions.

• How are simultaneous movements at different aerodromes detected and managed (slot coordination, clustering)?
• What is the maximum number of aerodromes per ATCO/AFISO, and under what traffic conditions?
• How is transfer of service between controllers at the RTC managed when demand at one aerodrome increases?
• What aerodrome clustering algorithm produces the safest and most cost-effective groupings?

Standards link. Doc 10007 §1.5.3 lists six factors specific to multiple aerodrome operations (resource management, CWP configuration, operating methods, ATM, clustering, approach control integration). These remain areas for ICAO standards development, as noted by AN-Conf/14 (Doc 10209 §3.20).

Regulatory status. EASA multiple mode AMC/GM (ED Decision 2019/003/R) represents the most detailed currently published regulatory guidance on this axis (authoritative source — not in local library).

Thread interaction matrix#

The six axes interact. Solving one without the others creates incomplete capability:

References#

• Doc 4444 (PANS-ATM), Chapter 7, §7.12.1.1 — reliability, availability, integrity; backup requirements.
• Doc 4444 (PANS-ATM), Chapter 2, §2.6.1.1 — mandatory safety risk assessment for significant ATS changes.
• Doc 10007 (AN-Conf/12 Report, 2012), Module B1-RATS, §5.1 — human factors and HMI as key enablers.
• Doc 10007, Module B1-RATS, §3.3 and §3.4 — contingency procedures for full and partial system failure.
• Doc 10007, Module B1-RATS, §1.5.3 — six factors for multiple aerodrome operations.
• Doc 10071 (Assembly A-39, 2016), §35.33 — human factors and performance-based provisions to guide regulation.
• EASA ED Decision 2019/003/R — competency requirements differentiating single mode and multiple mode (authoritative source — not in local library).

The Module concept in the RATS context#

In the ASBU framework, a module is the cell at the intersection of a block and a thread, carrying an operational improvement statement, a performance objective, procedures, technology, human performance requirements, and enablers. For RATS, the relevant module is B1-RATS: Remotely Operated Aerodrome Control.

This file works through two concrete cases — a single-aerodrome remote tower service and a multiple remote tower operation — and then examines the safety case process, which is the regulatory gateway for any deployment.

Case A — Single-aerodrome remote tower service#

Setting#

A small regional aerodrome (notionally: 10 000 to 30 000 movements per year, mixed IFR/VFR, occasional instrument approaches) is currently served by a locally-staffed AFIS unit. The local AFIS facility is aging; the ANSP's business case for a replacement tower building does not close due to low traffic volumes. The ANSP proposes to transfer service to a remote tower module at an RTC 180 km away.

System configuration#

• Two camera masts at the aerodrome providing 360-degree coverage of the manoeuvring area, circuit, and final approach path.
• PTZ camera (visible and IR) on the primary mast.
• ADS-B receiver at the aerodrome feeding aircraft position tracks.
• Wind sensor and RVR instrument readings fed to the RTC in real time.
• Remotely operable signal light on the primary mast.
• Primary fibre data link with 4G/LTE fallback.
• Single RTM at the RTC with a 240-degree wraparound display and a supplementary overview screen.

Operational flow#

Pre-movement: the AFISO at the RTC monitors the aerodrome panorama and the ATIS. Traffic information is provided to arriving VFR flights; IFR clearances are coordinated with the sector above.

Movement: the controller monitors runway occupancy visually on the panorama, augmented by ADS-B tracks. Radio communications are conducted on the aerodrome frequency, identical to a local deployment.

Low visibility: at reduced RVR the controller reads instrumented RVR values directly on the CWP display. PTZ cameras in IR mode provide usable imagery at night and in light fog.

Signal light: if a pilot loses radio contact, the controller activates the remotely operable signal light from the CWP; the light fires at the aerodrome in the correct direction toward the aircraft.

Performance claims#

Doc 10007 Module B1-RATS (2.1 Metrics) cites:

• Safety: equivalent to or better than local provision; digital enhancements in low visibility may provide improvement.
• Capacity: maintained or improved in low visibility via digital enhancements.
• Cost-effectiveness: reduction in shift size and tower facility costs; previous CBA indicated 10 to 35 percent staff cost reduction.
• Flexibility: extended operating hours feasible through centralized staffing.

Case B — Multiple remote tower operation#

Setting#

An ANSP operates four small aerodromes clustered within a 150 km radius. All four are AFIS-classified. Traffic patterns are complementary: two aerodromes handle morning commuter flows, two handle afternoon leisure traffic. Simultaneous movements at all four within a single hour are rare.

The ANSP proposes to serve all four from a single multiple-RTM position at an RTC, with one AFISO providing service across the cluster.

Operational model#

The AFISO's CWP has four aerodrome tiles. Each tile shows the panoramic view of one aerodrome at reduced size; the AFISO selects a full-screen view for the aerodrome with active traffic.

An automated demand prediction tool flags when traffic at a second aerodrome is approaching; the AFISO can preemptively coordinate slot delays at the second aerodrome to avoid true simultaneity.

When two aerodromes become active simultaneously, the AFISO and the RTC supervisor agree: the supervisor takes over one aerodrome at an adjacent CWP, or a pre-agreed reduction-in-service procedure is activated at the lower-priority aerodrome (holding all traffic until the AFISO is free).

Factors from Doc 10007 §1.5.3#

• Resource management: shift size determined by demand forecast; dedicated backup AFISO on standby during forecast high-demand periods.
• CWP configuration: one multi-aerodrome CWP for the cluster, with adjacent single-aerodrome CWPs for surge coverage.
• Operating methods: AFISO may monitor all four aerodromes when none has active traffic; transitions to focused attention when movements begin.
• ATM: ATIS updates coordinated across the cluster; ATFM slot management applied to scheduled arrivals to reduce simultaneity.
• Clustering: the four aerodromes were selected based on complementary traffic patterns and compatible airspace structures (non-overlapping CTRs, no common approach paths).
• Approach control: provided by the sector ACC above, not by the multiple remote tower AFISO.

Case C — Safety case structure#

A safety case for remote tower deployment typically follows the structure required by PANS-ATM §2.6.1.1 (safety risk assessment for significant changes) and reflects SMS principles from Doc 9859.

Step 1 — Define the change#

Describe the displaced service (local tower, staffing levels, procedures) and the proposed remote service (RTM specification, data link, procedures, fallback). Identify the operational differences.

Step 2 — Hazard identification#

Identify hazards unique to the remote mode:

• Loss of video stream (partial or total).
• Data link outage (aerodrome becomes effectively uncontrolled).
• Display latency exceeding tolerance (degraded situational awareness).
• Remotely operable signal light failure.
• Controller inability to perform physical tasks (e.g., FOD check).
• Cybersecurity events affecting the data link.

Step 3 — Risk assessment#

For each hazard: estimate likelihood of occurrence and severity of safety consequence. Tools: FMEA, fault trees, event trees. Reference: ICAO Safety Management Manual (Doc 9859).

Step 4 — Risk mitigation#

Assign safety requirements to mitigations:

• Redundant data link paths.
• Automatic alert when video latency exceeds threshold.
• Defined fallback procedure for video loss (equivalent to low visibility procedure — Doc 10007 §3.4).
• Local aerodrome personnel trained to support ATS suspension.
• Penetration testing and security controls for the data link (per AN-Conf/14 requirement, Doc 10209 §3.20).

Step 5 — Verification and approval#

Demonstrate that mitigations reduce risk to the target safety level. The ATS authority approves the visual surveillance system for the specific aerodrome (required by PANS-ATM §7.1.1.2.1). The approval is specific to each aerodrome — a system approved for aerodrome A is not automatically approved for aerodrome B if the physical geometry, traffic type, or operating environment differs.

Step 6 — Monitoring#

Post-implementation monitoring collects safety performance data against the predictions in the safety case. PANS-ATM §7.12.1.1 requires ongoing assessment of system failures and their impact.

Key regulatory test#

The overarching test, drawn from Module B1-RATS (Doc 10007 §1.1.3):

The concept does not seek to change the air traffic services provided to airspace users or change the levels of those services. Instead it changes the way those same services will be provided through the introduction of new technologies and working methods.

This means: the safety case must demonstrate that the airspace user experience — in terms of service type, responsiveness, and safety level — is not degraded. The approval is the ATS authority's confirmation that this test has been passed for the specific aerodrome.

References#

• Doc 4444 (PANS-ATM), Chapter 2, §2.6.1.1 — safety risk assessment mandatory for significant ATS change.
• Doc 4444 (PANS-ATM), Chapter 7, §7.1.1.2.1 — ATS authority approval specific to the visual surveillance system and aerodrome.
• Doc 4444 (PANS-ATM), Chapter 7, §7.12.1.1 — ongoing assessment of system failures; backup facilities or alternative procedures required.
• Doc 10007 (AN-Conf/12 Report, 2012), Module B1-RATS, §1.1.3 — change is to method of delivery, not to the services themselves.
• Doc 10007, Module B1-RATS, §3.3 and §3.4 — contingency procedures for full and partial failure.
• Doc 10007, Module B1-RATS, §1.5.3 — factors for multiple aerodrome operations.
• Doc 10007, Module B1-RATS, §2.1 — performance metrics: safety, capacity, cost-effectiveness, flexibility.
• Doc 10209 (AN-Conf/14 Report, 2022), §3.20 — cybersecurity as a required element of safety case and system design.

The enablers are the prerequisites without which remote tower operations cannot deliver their promised benefit. They are not themselves operational improvements; they are the conditions that must be in place before a remote tower service can be approved, deployed, and maintained.

1. Regulatory and certification enablers#

National regulatory framework#

The ATS authority must have a regulatory framework that:

• Recognises indirect visual observation as compliant with the aerodrome control service requirement (the PANS-ATM §7.1.1.2.1 basis exists; states must adopt it or enact equivalent national regulation).
• Defines the approval process for visual surveillance systems for specific aerodromes.
• Establishes the safety assessment methodology and the criteria for equivalence with a local tower service.

European status. EASA ED Decision 2019/003/R and the underlying Commission Implementing Regulation (EU) 2017/373 provide this framework for EASA-member states. States outside the EASA area must develop equivalent national frameworks.

System certification#

The remote tower system — camera array, data link, display system, signal light — must be certified or approved as airworthy or fit for purpose by the relevant authority. There is no global type- certification process analogous to ETSO/TSO for avionics; approvals are currently conducted on a system-by-system, aerodrome-by-aerodrome basis in most states.

ICAO status. AN-Conf/14 (Doc 10209 §3.20) requested development of standards for certification and validation of DATS system suppliers, noting the early stage and ongoing evolution.

Cross-border recognition#

Multiple remote tower centres may serve aerodromes in different states or FIRs. Cross-border operations require bilateral or multilateral agreements on:

• Mutual recognition of the system approvals.
• Applicable ATS procedures and which state's regulations govern.
• Contingency handover when service is suspended.

AN-Conf/14 specifically called for attention to cross-border operations in the ICAO provisions development (Doc 10209 §3.20).

2. CNS infrastructure enablers#

High-bandwidth, redundant data link#

The data link between aerodrome and RTC is the most critical single enabler. Requirements:

• Sufficient bandwidth for multiple simultaneous HD video streams.
• Low and stable latency (typically under 150-300 ms end-to-end for the video feed).
• High availability with a documented fallback path (secondary fibre, microwave, or cellular backup).

PANS-ATM §7.12.1.1 requires backup facilities or alternative procedures; for a data-link-dependent service, this translates directly to redundant link architecture.

ADS-B or multilateration at the aerodrome#

Position overlays in the RTM depend on cooperative surveillance at or near the aerodrome. ADS-B Out avionics in the aircraft fleet and a receiver at the aerodrome are the minimum requirement for the surveillance integration axis.

Meteorological instrumentation#

An instrumented aerodrome (RVR, wind, cloud height sensors) is a pre-condition. Without instrumented met data the controller cannot compensate for the absence of a direct physical sense of weather conditions that a local controller would have.

Annex 11 §7.1.4 requires aerodrome control towers to be supplied with meteorological information; this requirement transfers to the remote RTM, met by remote sensor feeds rather than local MET office co-location.

Remotely operable signal light#

A physical ICAO Annex 14 §5.1.3.1 compliant signalling lamp at the aerodrome with remote actuation from the RTM. This is a non-negotiable enabler: a controlled aerodrome must have a signalling lamp; if there is no controller in a local tower to operate it, it must be operable remotely.

3. Procedural enablers#

PANS-ATM approval and ATS authority determination#

PANS-ATM §7.1.1.2.1 requires that indirect observation be specifically approved by the appropriate ATS authority. This is not a generic approval; it is specific to the visual surveillance system at the specific aerodrome. The approval decision must be preceded by a safety risk assessment per §2.6.1.1.

Low visibility and contingency procedures#

Specific procedures must be established for:

• Loss of video stream: the contingency equivalent of LVP adapted for visual reproduction failure (Doc 10007 §3.4).
• Loss of data link: all ATS suspended; procedures for pilot self-separation, NOTAM, communication with inbound flights.
• Partial failures: degraded mode procedures commensurate with the capability available.

Aerodrome operations procedures for local personnel#

In a remote tower deployment, some physical tasks previously done by tower staff must be reassigned to local aerodrome operations personnel. Doc 10007 §1.1.9 notes that the ATCO/AFISO "will not have the ability to perform any tasks that are external to the control facility e.g. physical runway inspection." Procedures for:

• Runway inspection before opening.
• FOD (foreign object debris) checks.
• RASC (rescue and firefighting coordination) for emergencies. must be explicitly re-allocated and documented.

4. Human factors and training enablers#

Competency-based training adapted for remote operations#

Annex 1 (Personnel Licensing) controller competency requirements apply regardless of whether service is delivered locally or remotely (confirmed at ICAO Assembly A-39, Doc 10071 §35.33). However, the training environment must include:

• Familiarisation with the panoramic display and the visual presentation of the remote aerodrome.
• Practice in operating via indirect observation, including degraded mode and contingency scenarios.
• Specific training for multiple-aerodrome mode (if applicable), including attention management and demand prediction tools.

The Manual on Air Traffic Controller Competency-based Training and Assessment (Doc 10056) provides the framework; remote tower training programmes must be designed within it.

Rating and endorsement scheme#

States must determine whether remote tower operations require a specific endorsement on the aerodrome control (ADC) rating or the AFIS certificate. EASA multiple mode guidance introduces higher competency requirements for multiple mode operations than for single mode (authoritative source — not in local library).

Simulator / RTM training device#

Training for remote tower operations must use a simulator that replicates the RTM HMI, panoramic display, and sensor suite. This is a capital investment prerequisite for any RTC.

5. Institutional enablers#

ANSP business case and investment decision#

The primary driver for remote tower adoption is cost-effectiveness, particularly for small and medium aerodromes. The ANSP must demonstrate a positive business case before committing capital. Doc 10007 Module B1-RATS contains a generic CBA methodology showing 10 to 35 percent staff cost reductions depending on scenario.

Aerodrome operator cooperation#

The aerodrome operator must agree to the transfer of ATS from local to remote provision and accept the changed allocation of physical aerodrome tasks. Agreements on responsibility for local operations support must be documented.

Labour relations and staff transition#

Remote tower deployments typically involve relocation of tower staff from the aerodrome to the RTC. This requires consultation with staff associations and transition support. Doc 10007 §1.3.3 lists "more efficient use of staff resources" as one benefit but acknowledges transition costs including retraining, redeployment, and relocation.

Cybersecurity framework#

AN-Conf/14 (Doc 10209 §3.20) explicitly called for cybersecurity aspects to be included in DATS and remote tower provisions development. The data link between aerodrome and RTC must be protected. Enablers include:

• Network security architecture (segregated aviation network).
• Intrusion detection and response.
• Security testing before commissioning.
• Ongoing monitoring and incident response procedures.

References#

• Doc 4444 (PANS-ATM), Chapter 7, §7.1.1.2.1 — ATS authority approval requirement for indirect visual observation.
• Doc 4444 (PANS-ATM), Chapter 2, §2.6.1.1 — safety risk assessment requirement.
• Doc 4444 (PANS-ATM), Chapter 7, §7.12.1.1 — backup facility requirement.
• Annex 11, Chapter 7, §7.1.4 — meteorological information supply to aerodrome control towers.
• Annex 14 Volume I, Chapter 5, §5.1.3.1 — signalling lamp at controlled aerodrome.
• Doc 10007 (AN-Conf/12 Report, 2012), Module B1-RATS, §1.1.9 — remote ATCO/AFISO will not perform external physical tasks.
• Doc 10007, Module B1-RATS, §6.1.1 — no current regulatory or standardisation material at time of writing; assessment, development, and approval required.
• Doc 10071 (Assembly A-39, 2016), §35.33 — Annex 1 competency requirements apply at remote location.
• Doc 10209 (AN-Conf/14 Report, 2022), §3.20 — cybersecurity, cross-border, training, and licensing as required scope for ICAO provisions.
• EASA ED Decision 2019/003/R — European regulatory framework for remote aerodrome ATS including competency differentiation (authoritative source — not in local library).

Performance framework#

Remote tower operations are measured against the ICAO Key Performance Areas (KPAs) drawn from the Global ATM Operational Concept (Doc 9854) and the Manual on Global Performance of the Air Navigation System (Doc 9883). Module B1-RATS (Doc 10007) identifies four primary KPAs: Safety, Cost-effectiveness, Capacity, and Flexibility.

The chain from KPA to module benefit is:

KPA  --(measured by)-->  KPI  <--(targeted by)--  Performance Objective  --(achieved by)-->  B1-RATS deployment

Key Performance Areas and contribution#

Safety (KPA-10 in Doc 9883 notation)#

Objective: Remote tower operations shall not degrade, and should improve, the safety level of aerodrome ATS compared to the displaced local tower service.

How achieved: The safety case demonstrates equivalent or better performance. Digital enhancements (infrared cameras in low visibility; graphical surveillance overlays; automated alerts for runway incursions) may provide quantifiable safety improvements over the unaided window view.

KPI: Runway incursion rate per 10 000 movements; number of loss-of-separation events at the aerodrome; occurrences of ATS service interruption per month.

B1-RATS target: Same or better than baseline at the same aerodrome with a local tower.

Cost-effectiveness (KPA-03 in Doc 9883)#

Objective: Reduce the unit cost of aerodrome ATS at small and medium aerodromes; enable continued service at economically marginal aerodromes.

How achieved: Centralised staffing at the RTC; pooled training; standardised equipment across multiple RTMs; elimination of individual aerodrome tower facility maintenance costs.

KPI: Cost of ATS per movement at the aerodrome; cost of ATS as a percentage of aerodrome revenue; staff hours per movement.

B1-RATS target: Doc 10007 CBA indicated 10 to 35 percent reduction in staff costs per scenario; net-positive business case across a representative deployment lifetime.

Capacity (KPA-02 in Doc 9883)#

Objective: Maintain declared aerodrome capacity across all visibility conditions; improve throughput in low-visibility conditions relative to a local tower with no digital enhancements.

How achieved: Graphical overlays of surveillance data; infrared imaging; automated alert logic; instrumented RVR values visible on the CWP — potentially enabling normal operations at lower RVR values than a local tower unaided.

KPI: Aerodrome throughput (movements per hour) under VMC; aerodrome throughput under IMC / low visibility; proportion of planned movements completed without delay due to visibility.

B1-RATS target: At least equivalent throughput to local tower in VMC; improved throughput in IMC/low visibility conditions.

Flexibility (KPA-06 in Doc 9883)#

Objective: Enable extended service hours at small aerodromes beyond what a locally-staffed tower can sustain; allow reactive adjustment of service provision across the cluster in response to demand.

How achieved: Centralised staffing pool at the RTC makes it economically viable to extend opening hours; the multiple remote tower model allows reallocation of controller attention to aerodromes experiencing demand surges.

KPI: Service hours per day at the aerodrome; proportion of requested movements accommodated within the service window; number of opening-hour extensions per year after remote conversion.

B1-RATS target: Measurable extension of service hours; improved responsiveness to unplanned demand events.

KPA contribution matrix#

The following matrix scores each KPA by its principal benefit horizon across remote tower deployment stages (1 = some benefit, 2 = clear benefit, 3 = primary driver). Scores are editorial, consistent with the methodology in Doc 9883 and the Module B1-RATS performance narrative.

Access and equity (KPA-05 in Doc 9883) is particularly significant: remote towers enable continued or new aerodrome ATS at locations where the economics of a local tower would otherwise cause service withdrawal, maintaining access to the air transport network for regional communities.

Predictability benefits in the multiple remote tower model through slot coordination across the cluster, which reduces demand peaks and allows better service predictability for airspace users.

Applicable performance objectives (POs) from GANP Portal#

The GANP Portal catalogs Performance Objectives linked to the RATS thread (authoritative source — not in local library). Key POs aligned with remote tower deployments include:

• PO — Reduce ATS operating cost at smaller aerodromes. Drives cost-effectiveness KPI measurements. Delivered by B1-RATS single and multiple modes.

• PO — Maintain aerodrome throughput in low-visibility conditions. Drives capacity and safety KPIs. Delivered by B1-RATS with digital visual enhancement.

• PO — Improve service continuity and contingency resilience. Drives safety KPI. Delivered by contingency tower capability.

• PO — Extend aerodrome service hours for regional connectivity. Drives access and flexibility KPIs. Delivered by B1-RATS multiple remote tower mode.

Measurement and reporting#

Unlike en-route performance (where EUROCONTROL publishes regional KPIs through CODA/PRB annually), remote tower performance metrics are currently collected and reported at national or local level:

• ANSP internal reporting: safety occurrence rates, service interruption events, cost per movement.
• Regulatory oversight: ATS authority annual safety oversight report for each approved remote tower.
• SESAR 3 JU deliverables: performance measurement results from operational remote tower trials and early deployments.

ICAO global-level monitoring of RATS implementation is expected to develop as the module matures and more deployments accumulate evidence.

References#

• Doc 9883 (Manual on Global Performance of the Air Navigation System) — KPA definitions and KPI framework used throughout this file.
• Doc 9854 (Global ATM Operational Concept) — original KPA framework.
• Doc 10007 (AN-Conf/12 Report, 2012), Module B1-RATS, §2.1 — performance metrics: safety, capacity, cost-effectiveness, flexibility.
• Doc 10007, Module B1-RATS, §2.1 (CBA section) — 10-35 percent staff cost reduction estimate; positive business case conclusion.
• Doc 4444 (PANS-ATM), Chapter 7, §7.12.1.1 — requirement for no degradation in safety level of services rendered.

Historical evolution#

The remote tower concept evolved from early contingency facilities through research trials to the world's first operational service (2015) and the first European regulatory framework (2019).

Key inflection points#

2012 — ICAO normative introduction. Module B1-RATS in the ASBU framework (Doc 10007) established the global planning basis and the formal ICAO position that remote aerodrome control is a legitimate and desirable direction for ATM modernisation.

2015 — First operational service. Ornskoldsvik confirmed that the concept is not just theoretical; a remote tower can deliver daily, regulated aerodrome ATS to real traffic.

2019 — First comprehensive regulatory framework. EASA ED Decision 2019/003/R provided the first structured, published regulatory guidance covering the full mode spectrum (single, contingency, multiple). It demonstrated that regulation can be developed at regional level ahead of global ICAO SARPs.

2022 — AN-Conf/14 mandate. The call for ICAO to develop global provisions signals that the technology has matured to the point where the absence of global SARPs is becoming a barrier to broader deployment, particularly in cross-border and non-EASA jurisdictions.

ICAO ASBU block timeline#

References#

• Doc 10007 (AN-Conf/12 Report, 2012), Module B1-RATS, §7.1 and §7.2 — current use and planned trials as of 2012; Sundsvall-Ornskoldsvik development described.
• Doc 10007, Module B1-RATS, §1.3.2 — Heathrow virtual contingency facility as early precursor.
• Doc 10071 (Assembly A-39, 2016), §35.33 — Assembly direction for ICAO expert group consideration.
• Doc 10209 (AN-Conf/14 Report, 2022), §3.20 — Conference mandate for continued ICAO provisions development.
• EASA ED Decision 2019/003/R — 2019 regulatory milestone for European remote aerodrome ATS (authoritative source — not in local library).

Consolidated ICAO and authoritative external references for all files in this folder.

ICAO Standards and Recommended Practices#

• Annex 11 (Air Traffic Services), Chapter 2, §2.1 and Chapter 3, §3.6.1 — aerodrome control service definition and provision by an aerodrome control tower.
• Annex 11, Chapter 6, §6.1.1.3 — recording facilities required on all air-ground communications channels in ATC.
• Annex 11, Chapter 6, §6.4.1.1 — automatic recording of surveillance data from radar, ADS-B, ADS-C and similar systems.
• Annex 11, Chapter 6, §6.4.1.2 — surveillance recordings retained for minimum thirty days; longer if pertinent to investigations.
• Annex 11, Chapter 7, §7.1.4 — meteorological information requirements for aerodrome control towers.
• Annex 14 Volume I, Chapter 5, §5.1.3.1 — signalling lamp shall be provided at a controlled aerodrome in the aerodrome control tower.

ICAO Procedures for Air Navigation Services#

• Doc 4444 (PANS-ATM), Chapter 1 — definition of "Visual surveillance system" as an electro-optical system providing electronic visual presentation.
• Doc 4444 (PANS-ATM), Chapter 2, §2.1.3 — states shall ensure ATS are appropriate and adequate for maintaining an acceptable safety level.
• Doc 4444 (PANS-ATM), Chapter 2, §2.6.1.1 — safety risk assessment mandatory for significant changes to ATS procedures or introduction of new systems.
• Doc 4444 (PANS-ATM), Chapter 7, §7.1.1.2 — aerodrome controllers shall maintain continuous watch; watch by visual observation augmented by ATS surveillance systems.
• Doc 4444 (PANS-ATM), Chapter 7, §7.1.1.2.1 — visual observation shall be achieved through direct out-of-the-window observation, or through indirect observation utilizing an approved visual surveillance system.
• Doc 4444 (PANS-ATM), Chapter 7, §7.12.1.1 — visual surveillance systems shall have appropriate reliability, availability, and integrity; backup facilities or alternative procedures required; system failure modes shall be assessed.
• Doc 4444 (PANS-ATM), Chapter 7, §7.12.1.2 — visual surveillance systems shall receive, process, and display data from all connected resources in an integrated manner.
• Doc 4444 (PANS-ATM), Chapter 7, §7.12.2.1 — when approved by the ATS authority, visual surveillance systems may be used to perform all aerodrome control functions.
• Doc 4444 (PANS-ATM), Chapter 7, §7.12.2.2 — level of service commensurate with technical capabilities of the system.

ICAO Documents (Manuals and Conference Reports)#

• Doc 9854 (Global ATM Operational Concept) — KPA framework and ATM concept components used as performance basis.
• Doc 9859 (Safety Management Manual) — SMS methodology for safety case construction at remote tower deployments.
• Doc 9883 (Manual on Global Performance of the Air Navigation System) — KPA and KPI definitions; performance measurement framework.
• Doc 10007 (AN-Conf/12 Report, 2012), §2.1.3 — AN-Conf/12 endorsement extending the RATS module to the full spectrum of remote ATS.
• Doc 10007, Appendix B, Module B1-RATS, §1.1.1 through §1.1.10 — full operational concept description: definition, three elements, visual reproduction, out-the-window replacement.
• Doc 10007, Module B1-RATS, §1.3.1 through §1.3.3 — change description: single tower first, contingency evolution, improvements listed.
• Doc 10007, Module B1-RATS, §1.4 through §1.6 — three operational elements: single aerodrome, multiple aerodromes, contingency.
• Doc 10007, Module B1-RATS, §2.1 — performance metrics and cost-benefit analysis.
• Doc 10007, Module B1-RATS, §3.1 through §3.4 — procedures: maintenance of current air/ground procedures; new fallback procedures for failure scenarios.
• Doc 10007, Module B1-RATS, §4.1.1 through §4.1.3 — system capability: camera-based solutions, situational awareness, communication requirements.
• Doc 10007, Module B1-RATS, §5.1 and §5.2 — human factors and training.
• Doc 10007, Module B1-RATS, §6.1.1 — regulatory/standardisation needs require assessment, development, and approval.
• Doc 10007, Module B1-RATS, §7.1 and §7.2 — implementation and demonstration activities as of 2012; Sundsvall-Ornskoldsvik and Malmoe/Angelholm trials.
• Doc 10071 (ICAO Assembly A-39 Report, 2016), §35.33 — Assembly direction on remote ATS regulation; human factors, performance-based provisions; Annex 1 competency requirements apply.
• Doc 10209 (AN-Conf/14 Report, 2022), §3.20 — Conference call for ICAO provisions for DATS and remote towers; cybersecurity, cross-border, contingency, training, and licensing scope.

EASA and European regulatory documents#

• EASA ED Decision 2019/003/R — AMC/GM to Commission Implementing Regulation (EU) 2017/373; regulatory guidance for remote aerodrome air traffic services including single mode, contingency, and multiple mode (authoritative source — not in local library).
• Commission Implementing Regulation (EU) 2017/373 — establishing requirements for providers of ATM/ANS and other ATM network functions; basis regulation for EASA remote ATS AMC/GM (authoritative source — not in local library).

External references#

• https://ganpportal.icao.int/ - ICAO GANP Portal; RATS thread under the airport operations ASBU area.
• https://www.easa.europa.eu/en/document-library/acceptable-means-of-compliance-and-guidance-material/commission-implementing-regulation-eu-2017373 - EASA ED Decision 2019/003/R AMC/GM.
• https://www.eurocontrol.int/concept/remote-tower - EUROCONTROL remote tower concept and technical guidelines.
• https://www.sesarju.eu/projects/remote-tower - SESAR 3 JU remote tower solutions; single and multiple mode R&D outcomes.
• https://www.faa.gov/air_traffic/technology/remote_tower - FAA Remote Tower Programme; pilot programme and evaluation.