The goal of the system has been to provide, in actual time, the positions
and identifications of aircraft and vehicles equipped with the operational SSR
transponder. Output data can be provided to a multi-sensor fusion system as
well. The system was manufactured by ERA to meet the customer’s (Air Traffic
and Navigational Services - ATNS) surveillance requirements as follows:
In all visibility conditions the surveillance function of the system shall detect
and provide accurate positional information on all cooperative vehicles
within the movement area with Mode A/C/S transponders and ADS-B.
Provide automatic identification of all participating vehicles.
In the case of a multilateration solution, acquisition and extended squitter
messages shall also be used to determine the position of vehicles.
For ADS-B transponder equipped vehicles, the system shall be capable of
detecting and decoding all the ADS-B extended squitter messages.
The airport surveillance brings with it additional problems of radio shadowing
by urban objects with the number of receivers having to be set according to the
airport structure to ensure at least the minimal number of irradiated receivers.
In certain areas, additional receivers could serve for improvement in position
ERA was contracted to implement multilateration/ADS-B surface surveillance
systems at Cape Town Airport, South Africa as part of the consortium led by
French SEEE-IS (INEO). This consortium was awarded a contract by South
African ANSP ATNS to deliver a Multi-sensor Surveillance System (MSS) for CPT.
The pilot project begun in 2005 was intended to demonstrate the potential and
feasibility of multilateration systems in South Africa. ERA installed six ground
stations at the airport and three ground stations (WAM) in the surrounding
mountains. A successful trial period in Cape Town resulted in the certification
by the South African Civil Aviation Authority in 2006.
In early 2007, South African ATNS issued a RFP (request for proposal) for new
A-SMGCS systems for Cape Town together with Johannesburg to support the
upcoming World Cup competition. ERA was awarded a contract to provide the
Johannesburg airport with its MSS system and SQUID vehicle tracking units
and under this contract it was also tasked to extend Cape Town system’s
capabilities with additional sensors over a wide area (all together 6 after the
extension) and surface surveillance (currently 10 GS plus 15 SQUIDS).
The system is based on the TDOA multilateration principle and provides
accurate position and identification information of SSR transponder equipped
aircraft and surface vehicles by “multilaterating” of signals transmitted by the
transponders. The MSS is a system dedicated to providing surveillance data
of all Mode A/C/S transponder equipped aircraft and vehicles on the airport
surface and in the airport vicinity. It operates under all climate circumstances
concerning temperature (minus 15°C to plus 40°C) and relative humidity - 20 to
90 % with no condensation.
Air Traffic and Navigational Services
ATNS is responsible for
air traffic control over
approximately 10 % of the
world’s airspace. Its goal is
to provide safe and efficient
ATM solutions and associated
services and be the preferred
supplier to the African
Continent and selected
WAM Accuracy at
the flight level 100
(that means sea
level 3050 metres).
“The completion of this project is an important
achievement as ATNS continues to improve
the safety and capacity of ATNS's Air
Traffic Management systems. The
CAA certification demonstrates the
fitness of the ERA multilateration system
as an alternative surveillance method
to traditional SSR.”