Technology now enables the replication at remote sites of traditional 'out of the window' views from aerodrome visual control rooms by electronic means. This allows aerodrome Air Traffic Control (ATC) or Flight Information Service (FIS) to be provided from a location other than the aerodrome while maintaining a level of operational safety which is equivalent to what can be achieved using a manned tower at the aerodrome to oversee both air and ground movements.
Aerodrome Air Traffic Service (ATS) from a remote position is facilitated by the streaming in real time of the view from an assembly of fixed and moveable high definition digital video cameras situated at the remotely controlled aerodrome. This encrypted signal is used to replicate a view of the aerodrome and its vicinity which is equivalent to the view which would exist from a visual control room on the aerodrome. Fixed cameras provide the main display – these may be supplemented by other (such as ramp close-ups). Moveable cameras which can be directed as required from the may also be used to replicate the way binoculars might be used in a conventional tower. This visual situational awareness for the controller or flight information service operator can be supplemented by a range of environmental sensors and microphones capturing sound and meteorological or other operational data.
The CAA foresees the development and deployment of remote tower technology enabling the following types of operations:
- Replication of current on-site 'single mode' aerodrome remote tower including non-ATS surveillance-derived information. Examples of non-ATS surveillance-derived information include permanent or temporary mapping such as Work in Progress or surface markings. Replication enhanced by means of overlays of ATS surveillance-derived information, Secondary Surveillance Radar (SSR) data for example, is also envisaged.
- Remote Tower Centre (RTC) – multiple single mode applications or multi-site control at single work station.
The CAA has today published an initial update of its Policy concerning the approval of remote tower operations which revises a number of definitions and some technical content to align with the content of EASA ED 2019/004/R. The policy still addresses the following themes:
- Remote tower modes of operation and equipage levels, namely single/multiple modes of operation and basic/enhanced equipage levels.
- General requirements, including change management, ATS personnel licensing, camera operating systems, equipment interoperability.
- Specific considerations, including human factors, provision of meteorological and other ancillary services, ATS personnel interaction with on-site aerodrome personnel, service reliability and continuity, security, CNS considerations, signal lights and pyrotechnic signals, aeronautical information
CAP 670 development
CAP 670 will be amended in due course to reflect remote tower approval requirements. The following changes are anticipated (final text subject to outcome of the CAP 670 Air Traffic Services Safety Requirements consultation):
Part B Section 2 ATC 04: Remote Tower Operations
a. ATC04.1 ANSPs considering the implementation of Remote Tower operations are reminded of the requirements within Part A paragraphs A88-A92 for Change Notification, in particular A90 in regard to major changes.
b. ATC04.2 ANSPs shall consider the guidance included within Reference A
Part C Section 6: Remote Tower Optical Systems
a. RTOS01.1 ANSPs employing optical systems shall specify System Performance Requirements including Detection and Range Recognition Range Performance, Video latency, Video Update Rate, Video Failure Detection time, Point Tilt Zoom (PTZ) Function Control Latency, PTZ Function Movement Speed, and Time Synchronisation.
b. RTOS01.2 EUROCAE Document ED-240 'Minimum Aviation System Performance Specification for Remote Tower Optical Systems' provides guidance in developing these requirements and in verifying compliance.
c. RTOS01.3 ANSPs should consider Point and Zoom (PTZ) functionality using guidance from Reference A.
d. RTOS01.4 The visual presentation screens together with aerodrome ambient sound reproduction (if used) should be recorded. Where surveillance information is overlaid and/or integrated (in 'enhanced equipage') the recording of the screens will be a requirement.
e. Detailed requirements for recording and replay will be included in RTOS and will be largely similar to those for At-The-Glass Surveillance data described in SUR10
Part C Section 1: COM 02
a. COM02.36 will be updated to include data communications equipment used for links between VHF radio systems and the Voice Switch equipment (for example, as part of remote tower modules) within the definitions of main, contingency and emergency equipment.
Industry will be provided with advanced notification of the change.
ICAO, EASA, EUROCAE, UK and other remote tower regulatory material
ICAO Doc 4444 (PANS-ATM) Amendment 8, effective 8 November 2018 - introduces remote tower-related content into PANS-ATM
EASA has published the following remote tower-related Acceptable Means of Compliance and Guidance Material
- Guidance Material on remote aerodrome air traffic services Issue 2 dated 19 February 2019
- Part ATCO AMC & GM Issue 1 Amendment 2 Remote aerodrome air traffic services dated 19 February 2019
UK policy and guidance
- Policy for the Approval of Aerodrome Remote Towers
- CAP 670 ATS Safety Requirements
- CAP1620 Remote towers consultation
Eurocontrol is a further source of related material.