Situation Awareness in Air Combat

Copyright Peter Grining, 2000


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Air combat is largely the art and science of ‘situation awareness’. This can be defined as knowing what the enemy is doing and denying the enemy similar infromation. 75% of air combat is decided because the target did not see what shot them down. Targets must be detected, the information passed to fighters, the intercept made and weapons fired.

The Four Phases of Air Combat

Detection. Visual range 5-9 km, radar range tens to hundreds of kilometres.

Manoeuvre to engage (close). Cruise speeds result in speeds of ~250 metres per second, 10 km is covered in 40 seconds.

Engage - fire

Manoeuvre to disengage
Situation Awareness is mainly to do with the detection.

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Cockpit Design

Most fighter aircraft are fitted with two voice radios. One is set to GCI/AEW frequency, the other to the fighter flight frequency. This is subject to ‘own flight jamming’ as up to 40 aircraft try and talk to an AEW aircraft at the same time.

During the early days of 1991 Gulf War, AWACS was overwhelmed with radio calls. F-15 requests for target vectors went unanswered. The one US air to air loss of the war was a direct result of poor SA, as an Iraq MiG-25P used its superior speed to get in behind an USN F-18 and shoot it down. A similar incident happened during the 1999 Allied Force action over Kosovo. During an AWACS change-over USAF F-15 radio calls went unanswered.

The problem is still getting the information to the pilot. Voice radio can be jammed easier than datalink. Datalinks only require short durations to transmit information. With the right displays the information can be presented in and way that is easy for the pilot to take in.

Russian MiG-25 and US F-106 were fitted with datalinks and literally controlled from ground as far back as the 1960s. These aircraft had little information available to the pilot, the ground controllers had the full picture.

The USN F-14 Tomcat could track 24 targets, but the TID (Tactical Information Display) only shows 6 to remain readable. Max TID range scale is 740km. Other F-14, E-2 Hawkeye AEW or aircraft carriers could datalink other targets.

In 1987 Svenska Flyvapnet (Swedish Air Force) added a datalink from GCI to its JA 37 Jaktviggen. With this the ground based air defence system can provide target detection. The JA 37 can share information with other JA 37 such as which target each aircraft is attacking, fuel and weapons state and so on. In 1995 the ability to transmit simple text messages was added. The JAS 39 Gripen has increased capability with information shared between fighters, S100B Argus AEW, GCI radars, naval warships and SAM positions. 4-6 fighters would be spread over a distance of 120-150 km and share the same view.

Soviet fighters such as the MiG-29 Fulcrum and Su-27 Flanker require datalinks as they lack advanced radar features such as TWS. These datalinks are not fitted to export aircraft.

The US/NATO answer was JTIDS (Joint Tactical Information Display System) datalink and fighter displays. This was fitted to AWACS, some USAF F-15C, USN F-14D and RAF Tornado F.3. JTIDS was expensive and tried to present too much information on a 5x5 inch display with a range of 555 km(aircraft centred in middle). RAF Tornado F.3 fitted with JTIDS controlled by RAF AWACS fitted with ESM have defeated USAF F-15s in exercises using JTIDS. The AWACS would use its radar and ESM to detect targets, pass the information over JTIDS. The Tornado F.3 would stay passive (leave radars off) and get into AMRAAM launch parameters without activating radars. The USAF F-15s had little or no warning.

USAF and NATO F-16s are fitted with IDM (Improved Data Modem), which can share information between 4 aircraft. This system is cheaper and is more widely available. MIDS (Multiple Information Distribution System), a lower cost JTIDS will allow up to 8 aircraft to share information, with increased capability in the future. A typical MIDS installation will be 8 French Mirage 2000-5F linked to an E-3F AWACS with each aircraft having a designated transmit slot. Maximum time between updates is 2.5 seconds.

The answer for fighters was to have three separate displays. Generally the central one was the largest and provides the big picture, sometimes with a colour map, sometimes with just the FEBA marked. The left hand display might be the defensive display, which is circular with the aircraft in the centre. Known threats such as SAM ranges are presented as rings. The right hand display is the attack unit. This shows the aircraft at the bottom of the display and shows weapon allocation and other offensive information. This prevents having too much information on one display.

Before the F-18 Hornet, aircraft had dedicated ‘steam’ gauges for each instrument function. The Hornet introduced MFD (Multi-Function Displays). In the 1990s engines and other aircraft systems were so reliable, most fuel, oil, hydraulic, etc gauges have been removed.

Near future aircraft will have larger colour MFD which might be 178mm high (7 inches) and 127mm wide (5 inches), these can be used as a single window, but more typically split into two or three windows. A 127x127mm area might be used to show radar plan view (top ‘gods eye’ view), with a 51x127mm side view underneath. This increases SA by graphically showing target bearing, range and elevation. The 51mm could be split into two windows.

HUD (Head Up Display) provide a simple means of providing information, whilst the pilot is looking forward. HUD are developments of gunsights, with information projected up and onto the unit. With radar lockons, the HUD will put the outline of a box around the target and let the pilot know where the enemy aircraft is in, along with weapon acquisition zones. This decreases visual search time.

Heads level displays, under the HUD, leaves the pilot with more SA than heads down displays. The F-16C/D has a UFC (Up Front Controller), which groups the navigation, communications controls in one area. The Mirage 2000-5 has a head level display, which is used for the radar display. The MiG-23MLD has no separate radar display,and projects the radar information on the HUD.


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Radars

Typical radar search area is 60 degrees left and right of the aircraft nose and around 5-10 degrees up and down from the nose (a very thin ‘slice’ of the area a pilot needs SA available on). The scanner is moved from side to side at around 60 degrees/second. This beam is a few degrees wide and scans side to side several bars (stacked on top of each other). The radar scanner can be depressed (‘look down’) or elevated (‘look up’). Lookdown range is around 66% of level or lookup ranges. The computer revolution made the addition of Track While Scan (TWS) possible. This would open a file on aircraft detections so the radar would know where the target was and provide high quality ranges and speeds for weapon firings. The F-14 AWG-9 radar introduced pulse doppler, TWS and long range. The F-15 Eagle introduced HOTAS (Hands On Throttle And Stick) in 1974. This put the important weapon, radar, radio, decoy launcher buttons were the pilot has their hands in any case. This requires good training to take full advantage of HOTAS. The F-18 the first PSP (programmable Signal processor), allowing upgrades via software changes instead of replacing hardware.

Possibly the biggest advance with regard to ACM was the addition of a dedicated air combat mode. This mode would lock the target up automatically at around 20 km, slew an IRH missile seeker to the target, calculate firing parameters (ranges, angles, altitudes, etc) and give the pilot aural and visual indications of when to fire.

RCS

The base radar formula used is (RCS1/RCS2)^0.25. So the F-16C reduced RCS is 1.2 m2, standard fighter is 5 m2. (1.2/5)^0.25 = 0.69. Therefore the F-16C can be detected at 69% of radar range as compared with a standard fighter.

B-52 Bomber 100 m2 bomber range x1

F-4, A-10 25 m2 bomber x 0.71, fighter x 1.5

B-1B Bomber 10 m2 bomber x 0.56, fighter x 1.19

Tornado 8 m2 fighter x 1.12

Generic fighter 5 m2 fighter range x 1

MiG-21 3 m2 fighter x 0.88

F-16C/18C w. reduced RCS 1.2 m2 fighter x 0.7

F-18E, Rafale 0.75 m2 fighter x 0.62

Eurofighter 0.25-0.75 m2 fighter x 0.47-0.62

Exocet, Harpoon missile 0.1 m2 fighter x 0.38

JSF (‘golf ball sized’) 0.005 m2 fighter x 0.18

F-117, B-2, F-22 0.0001 m2 fighter x 0.07

F-117, B-2 F-22 also given as 0.01-0.001 m2, ‘marble sized’ or fighter x 0.12-0.21

F-22 RCS requirement was 1/1000th the F-15. This has probably be exceeded by a large margin. Even if the F-15 RCS is a large 25 m2, the F-22 is 0.025 m2 worst case (fighter x 0.26).
As can be seen ‘stealthy’ aircraft aim to reduce opposition situation awareness by decreasing detection range.

AEW/AWACS

A ground based radar might have a range against a low level aircraft of 60-90 km. Airborne Early Warning (AEW) is the general term to describe aircraft fitted with long range air search radars. This can mean the anything from the $500 million E-3 AWACS (with onboard fighter controllers and a command and control function) to the Swedish $50 million S100B Argus (no controllers and datalinks the radar data to ground control).

During the battle of Guadcanal in 1944, APS-20 radars were fitted to USN Avenger aircraft for the sole purpose of detecting Japanese kamikaze aircraft under Project Cadillac I.

Early efforts evolved into long range aircraft fitted with radars. These AEW aircraft would increase warning time of enemy air strikes. The US Navy and Air Force efforts started to pay off in the Vietnam War and lead to the E-3 Sentry.

In 1977 the E-3 Sentry entered service for the Airborne Warning And Control System (AWACS). The APY-1 ‘flying saucer’ radar was fitted to the back of a Boeing 707. It was no longer an airborne radar it was a battle management command and control post in its own right. AWACS can control entire missions by vectoring aircraft to air-to-air tankers, providing warning of enemy aircraft and co-ordinate SAR. Users include the USAF (33 E-3A/B/C), RAF (7 E-3D), France (4 E-3F), NATO (18 E-3A) and Saudi Arabia (4 E-3A). Patrol height is 30000 ft (9144 metres). NATO callsign is ‘Magic’. Aircraft crew is 4 (pilot, co-pilot, navigator, flight engineer) with 13 mission crew. Three are maintenance technicians (communications, displays, radar) and one operates the communications. The tactical director is in overall command of the two sections. The Weapons section consists of three: the fighter allocator and two weapons directors who talk to other aircraft. The Surveillance Section is headed by the surveillance controller, two surveillance operators, datalink manager and ESM operator.

The 1982 Sea King AEW.2 with a Searchwater radar can manually track 16 targets and control 4 intercepts by voice radio. The near future Sea King AEW.7 with Searchwater 2000 will be capable of 600 tracks and be equipped with a datalink.

The advantage of AEW over fighter radars is the long range, 360 degree coverage and personnel numbers to take advantage of this.

AEW ranges Fighters Bombers

E-2 Hawkeye w APS-138 220 km 463 km

E-2 Hawkeye w APS-145 267 km small, 400 km large ~565 km+

E-3 Sentry APY-1/2 267 km small, 400 km large ~565 km+
Around 20-40 seconds track new target

Wedgetail MESA 350 km small fighter ~745 km

Israeli Phalcon same as APY-1/2. 2-4 seconds to track target.

Russian Tu-126 w Liana 100 km 200-300 km

A-50 w Shmel 100+ km 200-300+ km

A-50U w Shmel II (mid-90s) 230 km MiG-21 (small fighter) ~500 km
Tracks 40, controls 10 intercepts

Russian Ka-29 RLD/31 147 km ~250 km
May track 20 targets.

Swedish Erieye 225 km small, 340-350 km large 450-480 km
No onboard operators, links information to GCI.

Fighter radar ranges

Aircraft/Radar Fighter Bomber

EL/M-2032 47 km 100 km

Eurofighter Captor (ex-ECR-90) ~175 km 370 km

JA.37 Viggen PS-46/A 75 km max

JAS.39 PS-05A 90 km 190 km

F-4 AWG-10 38 km 80 km

F-14A/B AWG-9 210 km 330 km

F-14D APG-71 ~175 km 370 km

F-15 APG-63/70 110-160 km 240 km

F-15 APG-63(v)2 195 km 410 km

F-16 APG-66 ~55 km ~105 km

F-16 APG-66(v)2/3 70 km 130 km

F-16 APG-68 80 km 140 km

F-16 ABR 130 km 275 km

F-18 APG-65 ~72 km ~ 150 km
TWS of 10 targets at 74 km. HUD acquistion auto lock at ~9 km.

F-18 APG-73 (APG-65 x 1.2) 85 km ~180 km

F-20 APG-67 90 km ~130 km max

F-22 APG-77 230 km 490 km

MiG-21 RP-21 Spin Scan 9.5 km 20 km max

MiG-21 RP-22 Saphir-21 14 km 30 km max

MiG-23 High Lark 33 km 70 km

MiG-23ML Sapfir-23ML 40 km 85 km

MiG-25 RP-25 Smerch-A 47 km 100km

MiG-25 Sapfir-25 66 km 140 km

MiG-29 NO-19 Slot Back 70-100 km 100-150 km
Tracks 10 targets, guides against 1.
MiG-29 NO-10 88 km 186 km

MiG-29 SMT-II NO-19ME Topaz 130 km 275 km

MiG-31 Zaslon 110 km 240 km
Tracks 10 guides 4

MiG-35 RP-35 140 km 300 km

Mirage F.1 Cyrano IV 45 km 96 km max

Mirage 2000C-S1 to –S3 RDM 85 km 110 km

Mirage 2000C-S4/5 RDI 110 km 190 km

Mirage 2000-5 RDY 130-140 km 275 km

Rafale RBE vs 130 km 275 km

Sea Harrier FRS.1 Blue Fox 37 km 95 km

Sea Harrier FA.2 Blue Vixen 110+ km 150 km max

Su-27 110 km 240 km max

Su-35 planned to be: 190 km 400 km

Tornado F.3 AI24 Foxhunter 100 km 210 km
w. Stage 2G radar (1991) 185 km large fighter 260 km
Track 40 targets. Originally no close range modes.

RWR/ESM

The 1960s saw aircraft fitted with RWR (Radar Warning Receiver), which as the name suggest gave an aural and display warning of a threat. Later the RWR computer would be programmed to give an indication of the type of radar and so on. By 2010 the USAF/USN would like all its fighters fitted with an ELS (Emitter Location System). ELS are used by Wild Weasel aircraft to determine ground based radar location by triangulation.


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IRST

IRST (Infra-Red Spot Trackers) provide bearing indication of heat sources (aircraft engines). These do not provide range, but are entirely passive. MIG-29 range 30 km


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Helmet Mounted Sights - HMS

The USN had a VTAS on some F-4 in the 1970s. This took on the radar ACM function and actually aimed the radar which supplied information to the missiles, as well as aiming these. This technology was not pursued by the US after this time. The Soviets had a similar system fitted to the MiG-29 in 1985. This used head trackers and a fixed sighting reticule to slew the IRST/laser rangefinder to the target. However good visual conditions are required for HMS use. Israel introduced the first true HMD, which replaces the simple reticule with visor projection system similar to a HUD.


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Other Technologies

IFF: Identification Friend or Foe. IFF interrogators send a coded radar pulse with a time signal towards an unidentified contact. The contact IFF receiver return is sent on another channel, also with a timed pulse. This gives a bearing and distance which is shown on the radar display. IFF actually only identifies friendly aircraft with a working transpoder. A contact may be friendly with a faulty unit (or the interrogator unit might not be working) or a hostile.

In 1972 USAF F-4D were fitted with APX-81 Combat Tree. This was a classified program, and worked by picking up North Vietnamese MiG SRO-2 IFF sets. Combat Tree could identify a ‘blip’ on a radar scope as hostile. The F-4 pilots would clear the shot from Red Crown (EC-121 AEW) or check with their wingman Combat Tree set. This trick was a one off as IFF sets increasingly had encryption added.

Out of the mid-1970s ‘Musketeer’ program, the idea of using radar to count the fan blades in the contact’s engine (front or back) to identify aircraft was thought possible. This radar signature was unique to each aircraft (sometimes different models of the same aircraft). This technology, known as NCTR (Non Co-operative Target Recognition), had to wait until mid-1980s computer technology caught up. From 1985 USAF F-15C had NCTR modes added. During the 1990-1991 Gulf War, the USAF decided the ROE would be for each fighter requiring two methods of IDing a target. One method was AWACS, the other accepted method was NCTR. F-15C were the only coalition fighters allowed to operate over Iraq, NCTR was one of the reasons. During the next 10 years NCTR was fitted to US F-14, F-16 and F-18s, selected foreign F-15 , UK Tornado F.3 (early-mid 1990s), and French Mirage 2000-5F in the near future.


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Twilight War

AWACS was widely available to NATO and was a huge advantage. However the ‘close-in’ fighting over Germany and Poland, most NATO fighters lacking datalinks sometimes meant aircraft were not passed target information in time to make use of this.

Soviet fighters were actually fitted with datalinks on a more widespreas basis than NATO. They, in most cases, lacked the training and user friendly technology to take advantage of the increased SA.

NATO thought Warsaw Pact depended too much on GCI, Pact thought NATO depended too much on AWACS. Both were right, fighter pilots require some form of outside guidance.

In any case, the high tech portion of the Twilight war lasted around 12 months, November 1996 to November 1997, with the majority of modern aircraft lost before the nuclear exchanges.


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2300 AD

By 2300 it is possible that the large radar aircraft AWACS of today will be gone. The concept being talked of is called ‘reach-back’. This would leave the command and control assests in the rear areas, collecting space based or UAV sensor data, and passing this to fighters operating over the battlefield. AWACS will be be more widespread, the technology cheaper. The ‘The Game’ mentions AWACS, they are presumedly talking about generic sensors and C&C assests, be they radar planes, satellites and so on.


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Conclusion

Air combat is about SA, not high agility maneuvring or aircraft performance (although these help). Stealth and counter-stealth is important, as this directly deprives SA to the enemy and allows friendlies to gain advantage. As information warfare matures, off-board sensor information will become more important. Of equal importance is providing the aerial weapons platform, a manned fighter or UCAV (Uninhabited Combat Aerial Vehicle), with this information.


http://www.users.globalnet.co.uk/~dheb/2300/Articles/PG/PGSA.htm