Airborne Surveillance Platform
Encyclopedia
The Airborne Surveillance Platform (ASP) is an India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

n defense project, initiated by the Defence Research and Development Organization, which aimed to produce an Airborne Early Warning
Airborne Early Warning
An airborne early warning and control system is an airborne radar system designed to detect aircraft at long ranges and control and command the battle space in an air engagement by directing fighter and attack plane strikes...

 System. Two prototypes were developed and flight tested for three years. The project was cancelled in 1999 after the prototype aircraft crashed, killing 8 scientists and aircrew. After four years of inactivity, the project was revived in 2004 with a new platform and radar.

Origins

The ASP programme, code-named "Airavat", is one of the key force multipliers in the modern war scenario. India's Defence Research and Development Organisation
Defence Research and Development Organisation
The Defence Research and Development Organisation is a agency of the Republic of India, responsible for the development of technology for use by the military, headquartered in New Delhi, India...

 (DRDO) is developing an advanced surveillance platform based on an Hawker Siddeley HS 748 aircraft to detect targets at extended ranges with all round azimuth coverage. It is designed to handle 50 targets. It features a Hybrid navigation system, including both satellite and ground (beacon) based topography. The communication and data links are dual redundant secure systems.

The origin of the program possibly lies in the aftermath of the 1971 Indo-Pak war. As witnessed by the air-operation in the western front, timely information and coordination, namely vectoring and interception cannot be done effectively from the ground. In the late 1979, the DRDO formed a team to study the possibility of mounting an airborne radar on an existing aircraft.

The problem was not the availability of suitable aircraft but the lack of an effective airborne radar. An ad hoc team of specialists from LRDE began work on developing an airborne radar, allowing the program to proceed. Studies and analysis began in July 1985 under project name 'Guardian', later it was renamed 'Airawat'.(Possibly in 1987) In the late 1980s an HS 748 was fitted with a 24 ft x 5 ft composite rotodome. The aircraft flew with the pylon, but not the dome, in May 1989 and with the rotodome in November 1990. The Centre for Airborne Systems (CABS
Centre for Airborne Systems
The Centre for Airborne Systems is a laboratory of the Defence Research and Development Organisation of India. Located in Bangalore, its primary function is development and evaluation of airborne electronic systems for military applications....

) was set up in February 1991, under Dr K. Ramchand to act as a system house and integration agency using all the expertise and infrastructure available in India. At the peak of its operations, some 300 Scientists and Engineers were involved in the project. The aircraft was unveiled to the public during flight demonstrations at the inauguration ceremony of the first Aero India show held in Bangalore in December 1996. Two testbeds transferred from the IAF's western command were employed in the design program, with tail numbers H-2175 & H-2176.

SP Antenna & Rotodome

The Antenna is a slotted wave guide planar array and features very low side lobe levels and a narrow beam width in azimuth. It handles high power (better than 3.3 KW average) and weighs just 160 kg. For housing the primary and the secondary (IFF) antennas, an ellipsoidal structured (7.315 m x 1.524 m) rotodome was fabricated. It is made up of composites and aluminium alloy parts and is driven by a hydraulic servo system using aircraft hydraulic power. The rotodome has since been successfully flight tested with the ASP system.

Airborne Data Processor

The airborne radar data processor (ARDP) supports track-while-scan (TWS) which is required to form target tracks after receiving data from the various sensors of ASP, such as the primary radar (PR) and the secondary surveillance radar (SSR), which operate in TWS mode. The ARDP correlates the target plots from scan to scan to maintain the target tracks. It also correlates target information obtained from SSR and endorsement with the PR track information. In May 1997, all the requirements were met and the system was delivered to CABS for integration.

Integrated Navigation System

The ASP is guided by a high accuracy navigation system, which consists of an inertial navigation system (INS) and a Doppler navigation system. The velocity drifts of INS are contained by Doppler velocities using a Kalman filter
Kalman filter
In statistics, the Kalman filter is a mathematical method named after Rudolf E. Kálmán. Its purpose is to use measurements observed over time, containing noise and other inaccuracies, and produce values that tend to be closer to the true values of the measurements and their associated calculated...

, resulting in good navigation accuracy required for long endurance missions of ASP. Presently, Work is in hand to integrate GPS/GLONASS
GLONASS
GLONASS , acronym for Globalnaya navigatsionnaya sputnikovaya sistema or Global Navigation Satellite System, is a radio-based satellite navigation system operated for the Russian government by the Russian Space Forces...

 receivers with INS to enhance performance, reliability and robustness.

Integration, trials & crash

System integration began in the late 1980s and by 1989 HAL had modified three HS 748 aeroplanes with pylons as well as an additional APU to power the rotodome hydraulics, computers, communications and the experimental gear aboard. Trials began in 1989 and the complete aircraft flew for the first time in November 1990.

The trials lasted for approximately 3 years until the ARDPs had to be replaced with a newer variant and the trials were suspended pending completion of the upgrade. In 1995 when the tests resumed, the platform was meeting most of the program goals. At the same time however, the Air Headquarters staff re-affirmed previous doubts about the specifications meeting their requirements. This led to the Defence Ministry informing the Air Headquarters & Air Force that the ASP was not expected to meet their requirements, but rather to study the possibility of providing an airborne EW platform and gain development experience. Though observers point to these differences as the reasons contributing to the handing over of the ASP to the Indian Navy
Indian Navy
The Indian Navy is the naval branch of the armed forces of India. The President of India serves as the Commander-in-Chief of the Navy. The Chief of Naval Staff , usually a four-star officer in the rank of Admiral, commands the Navy...

 rather than the IAF, both the Indian Navy and Air Force originally helped define the requirements.

After this clarification, the project progressed with renewed vigour, only to be set-back again on 12 January 1999 when the second prototype crashed. The first prototype being just a test-bed for pylon studies. Two crew, four scientists and two IAF engineers died in the crash, a total of eight people, with no survivors.

CABS

The Defence Ministry set up a dedicated laboratory, namely CABS
Centre for Airborne Systems
The Centre for Airborne Systems is a laboratory of the Defence Research and Development Organisation of India. Located in Bangalore, its primary function is development and evaluation of airborne electronic systems for military applications....

 (Centre for Airborne Systems) in February 1991 for progressing the technologies and sub-systems necessary for the ASP. The main task allotted to the CABS was design, development, integration and evaluation of airborne electronic systems on a suitably modified flying platform for surveillance of airspace together with command and control functions besides transfer of appropriate technologies to industry. Besides CABS, LRDE, Gas Turbine Research Establishment were entrusted with the development of ASP sub-systems.

Strategy and Execution

The strategy adopted by CABS involved the development of an ASP using rotodomed HS 748 aircraft as the flight test bed, in the first phase for the development of the indigenous Airborne Early Warning technology to be evolved on a step by step, modular, low cost and low risk approach.

Platform

Though the selection of this particular platform has drawn much heat from many quarters, there really was no alternate platform available with India then. Particularly, this was an issue because the Indian Airlines had recently (in 1989) phased out the HS 748 completely, citing passenger safety. Though the IAF continued to operate them in logistics role, the top-brass certainly did not want it to be the platform for an AEW aircraft.

Air HQ's statements

In October 1992,the air HQ while commenting on the system specification document stated, that while the specifications were meant for ASP and is not expected to meet the Air Staff Requirements at that stage. Also the statement expected that the design philosophy was targeted towards meeting the Air Staff Requirements at a later stage. The Ministry stated, in February 1999, that ASP was not meant to meet the requirements of users but to induct and demonstrate the technology by utilizing the only viable platform. The fact, however, remains that the ASP development programme was taken up as a first step towards the development of full fledged AWACS, the need for which was projected by the Services in early 1980s.

Closure

Following the 1999 crash, the ASP programme had been pushed back for about 3 years. But due to the differences in opinion and chiefly due to the reported unreliability of the HS 748 platform, the project had been shelved.

Revival

However, by mid 2002 the project was "re-activated" , according to various news reports. As of March 2007, CABS was working on developing another indigenous airborne early warning (AEW) system. According to the Defence Minister, completion of development activities and commencement of user trials should occur in 2012. The platform selected this time is Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...

ian Embraer
Embraer
Embraer S.A. is a Brazilian aerospace conglomerate that produces commercial, military, and executive aircraft and provides aeronautical services....

 with CABS AESA Radar.

The new system will be based on the Embraer
Embraer
Embraer S.A. is a Brazilian aerospace conglomerate that produces commercial, military, and executive aircraft and provides aeronautical services....

 EMB-145 aircraft and an active phased array radar. IAF and army propose to use this mini-AWACs systems as a compliment to the larger AWACS system being imported from Israel. The Union Cabinet has already given a green signal to the development of such an aircraft-based system.

Goals of the AEW & C Program:
  • AEW
  • Nodal AWACS function(s) in the National Grid (functioning in tandem with Phalcon)
  • Comint capabilities.
  • Sigint
    SIGINT
    Signals intelligence is intelligence-gathering by interception of signals, whether between people , whether involving electronic signals not directly used in communication , or combinations of the two...

     capabilities.
  • IFR capabilities.


Functions/features
  • Asynchronous/Synchronous Datalink between 40 aircraft.
  • Hybrid Inertial/Satellite Navigation System.
  • Integrated IFF
    Identification friend or foe
    In telecommunications, identification, friend or foe is an identification system designed for command and control. It is a system that enables military and national interrogation systems to identify aircraft, vehicles, or forces as friendly and to determine their bearing and range from the...

     with mode-4 capability.
  • Multiple Redundant Air to Air datalinks.
  • Multiple Redundant Air to ground datalinks.
  • Satcomm Links.

External links

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