When working in Track-While-Scan mode, the AWG-9 emissions were difficult to identify for contemporary radar warning receivers, and thus warning of an attack undertaken by an F-14 Tomcat was minimal — if there was any.
Equipped with well-balanced air wings, huge aircraft carriers have formed the backbone of the US Navy’s doctrine and strategy since the Second World War. Packing an enormous punch, their purpose is to exercise control over enormous portions of airspace – in the offence or defence.
From the mid-1970s until the mid-2000s, the tip of the spear of the US Navy air wings was the famous Grumman F-14 Tomcat -widely considered one of the finest air superiority systems in the world. Originally designed as a fast, manoeuvrable and well-armed fighter, the Tomcat entered service as the ultimate long-range fleet defender and became the biggest, most complex and most expensive naval aircraft of its time.
As explained by Tom Cooper in his book In the Claws of the Tomcat: US Navy F-14 Tomcats in Air Combat against Iran and Iraq, 1987-2000, the capability offered by service entry of the F-14 far surpassed the significance of ‘introducing a new fighter aircraft’: it propelled Navy’s Tomcat’s squadrons into a position of dominating the aerial warfare of the late 1970s and all of the 1980s. The principal reason for this was a weapon system that — even if centred on a much upgraded version of a radar originally developed in the late 1950s and the early 1960s — was still ahead of its time and easily outmatched nearly everything available anywhere else. Its core was the AWG-9 radar and fire-control system that, from the front towards the rear, included a total of 27 units, starting with the planar-array radar antenna with 91.4cm (36in) diameter, an antenna controller, synchronisers, microwave circuits and Doppler clutter processors, digital computers, fire control system, cockpit displays, and two data-links. The installation of all this equipment into a single aircraft was possible due to huge advances in the design of radars and computers during the 1960s: while still an analogue system, the AWG-9 incorporated the second generation of solid-state technology including throughput processors, coherent transmitters and amplifiers, microprocessors (necessary to filter ground clutter and enable tracking of low-flying targets), entire new tracking algorithms, and was capable of emitting at a new, high pulse repetition frequency (essential for ultra-long-range detection capability). The peak output was 10.2kW, which made it the most powerful airborne intercept radar in operational service on combat aircraft until the service entry of the Lockheed F-22 Raptor equipped with the APG-77, in 2005.
The AWG-9 was extremely versatile: it had six basic working modes (four of which were pulse-Doppler), with 19 transmission channels for pulse-Doppler search signals, of which 6 were for guidance of AIM-54 missiles, and 5 for A1M-7s. The longest-ranged working mode was the Pulse-Doppler-Search (PDS), which offered the ability to detect bomber-sized targets from as far 277km (150nm) and fighter-sized targets (radar cross section of less than 5 square metres, like the MiG-21) from 213km (115nm). The Pulse-Doppler Single Target Track (PDSTT) mode was used for long-range AIM-54 shots and for attacks on targets emitting strong electronic countermeasures (ECM), but could also be deployed to guide AIM-7 Sparrows out to a range of 70km (38nm) or AIM-9 Sidewinders out to a range of 16km (10nm). Perhaps the most important was the Track-While-Scan (TWS) mode, in which the AWG-9 had a maximum detection range of 166km (90nm), but could scan immense volumes of airspace (about 15 times more than best system ever installed into the F-4) while simultaneous; tracking up to 24 targets — six of which could be engaged with AIM-54 missiles at the same time. All of these working modes enabled look-down/shoot down engagements (i.e. targeting of objects operating at very low altitudes): moreover, when working in the TWS mode, the AWG-9’s emissions were difficult to identify for contemporary radar warning receivers, and thus warning of an attack was minimal — if there was any.
While most of these working modes could be used for setting up attacks in which the fire-control system was selecting targets and releasing AIM-54s on its own – indeed: in automatic mode – the AWG-9 retained its ‘old school’, man-in-the-loop pulse radar modes, enabling the radar intercept officer (RIO) in the rear cockpit to ‘manually’ pick up weak radar returns out to the range of 91km (49nm) in Single Target Track — or 115km (62nm) in Pulse Search mode. Finally, the radar had three air-combat modes (Pilot Lock on Manual Rapid Lock on and Vertical Scan Lock on), enabling the crew — foremost the pilot — to quickly lock on to targets engaged in close-in air combat at ranges out to 9.23km (9nm).
Weapon firing was performed by a separate fire-control computer, the AWG-15, while the problems inherent in using four different weapons in rapid succession and without particular order were solved by using an integrated armament control system. Alternatively, all the weapon options could be pre-programmed and stored prior to take-off, in which case every weapon was instantly prepared for launch at the touch of a switch.
In the Claws of the Tomcat: US Navy F-14 Tomcats in Air Combat against Iran and Iraq, 1987-2000 is published by Helion & Company and is available to order here.
Photo credit: Lt. Gerald B. Parsons / U.S. Navy