During the mid-eighties, the FB-111A undergone a much needed modification to its avionics subsystems. Outside of software updates to its various mission computers, modifications to enhance capability since that time had been limited to SRAM installation, ECM upgrades and the addition of the AFSATCOM system. Initiated by the Air Force Logistics Command's Sacramento Air Logistics Center at McClellan AFB, Ca., the $142 million Avionics Modernization Program involved the replacement of selected components of the aircraft bombing and navigation system. It was designed to improve combat relaibility and maintainability of the aircraft by integrating current off-the-shelf technology hardware into the sytem. According to AFLC officials, the AMP was to project a $30 million savings in spare parts, reducing spare parts inventory because of increased reliability. It was also to improve built-in tests and greatly decrease maintenance time. These improvements were expected to increase the commonality of components used in the various models of the aircraft, helping drive down support costs. The major components of the AMP were two inertial navigation units, an updated terrain-following radar system, a new attack radar indicator, the two multifunctional displays (MFD), an updated Doppler radar system and the integrated comm./nav. identification system (ICNIS).
Training the crews to operate the new equipment posed a challenge. Since the simulators were not scheduled to be modified with the AMP configuration until the deliveries were half complete, an interim device was needed to meet the aircraft delivery schedules. A table top computer based training device was procured by the 436STS at Carswell AFB.
The INS had proven extremely reliable. It was not uncommon to enter a low level route two hours after take-off with only one position fix in the system and an error of less than 1000 ft. The system automatically switched to the good INS should the other malfunctionned. If both systems malfunctionned, you could put either INS into a special mode to give you altitude information. The multifunction displays made bombing and navigation data easily accessible for both crew members. It provided a good backup system for the pilot to make sure the navigator had the right destination or target called up, and is in the navigation or bombing mode. The pilot normally used the left MFD. It could display heading, track, airspeed, groundspeed, distance and time to the destination or target, and wind information. The old radar system with its familiar orange glow was replaced by a new system using a green background. The navigator had every piece of information he could want displayed on the radar scope. This included the information that was displayed on the left MFD, plus distance to the crosshairs in feet, what sensors were selected (usually the Doppler and both INS), and wether manual or auto ballistics were being used. There was also a clock on the radar scope. The entire display, along with all radio and interphone communications were recorded on a pocket-size videocassette. The integrated communication-navigation system was a real crowd pleaser. The system controlled the UHF radio number two, the TACAN, ILS and IFF systems, as well as the HF radio. A small monitor on the control display unit (CDU) on the navigator's side panel showed what equipment was on, which frequencies were selected, and what IFF modes were on or off. You simply pressed the number of the preset you wanted, pressed enter, and it's set. Manual frequencies were set the same way. When you could not contact someone on a new frequency, you'd press the enter button again, and the old frequency was displayed.AFLC was responsible for all AMP integration activity. But Sacramento ALC wich provided system program management for all versions of the F/FB/EF-111, had also been delegated management responsability for AMP as it applied to the F/FB-111. This responsibility included laboratory, ground and flight testing of the modified syatem. There was two phases of flight testing conducted at McClellan AFB: dedicated and integrated. The goal of this test was to perform what was called developmental test and evaluation on two major subcomponents of the AMP, the terrain-following radar and attack radar systems. The work was accomplished with two F-111s. The first, an F-111D, was used to test the new terrain-following radar system which gave the F-111 its capability to fly automatically at extremely low altitudes in all weather conditions. The second aircraft, an FB-111A, was used to test the new attack radar system. The USAF delivered an operational FB-111A (68-0247) to Fort Worth to serve as the trial installation aircraft for the FB-111 Avionics Modernization Program. The aicraft received all AMP modifications during the next 18 months and was scheduled to undergo ground and flight testings beginning in mid-1985. The principal upgrade under the program, in which the entire USAF FB-111A fleet was going to be modified, was the replacement of a first-generation, 20 year-old digital bomb navigation system with a modern digital system. This and other AMP modifications offered significant improvments in reliability and maintainability at reduced logistic support cost. After the dedicated testing was done, AMP entered the second phase, integrated testing.
The first FB-111A to be modified in the AMP program returned to Pease AFB on Dec.18, 1986. Two days after formal roll-out ceremonies for the aircraft were held at Wright-Patterson AFB, Gen. Earl T.O'Loughlin, AFLC's commander flew in the first FB-111A for the 509th BW. The general was proud to say; 'Since so much effort has been put into it, we want to take care of it well. I think it's particularly fitting that the first modified aircraft was delivered to the 509th Bombardment Wing where the wing was recently named the "Best in SAC" for aircraft maintenance and as the "SAC Daedalian Maintenance Award" winner.'The first Plattsburgh AFB's FB-111A to be modified under the AMP was delivered to the 380th BW on Oct.19, 1987 by Brig.Gen.Charles J.Searock Jr. The general, a former 380th BW's commander was deputy chief of staff for logistics at Headquarters Strategic Air Command. General Searock was met by Col.C. Jerome Jones, 380th BMW commander, and several senior wing officials and dignitaries. Capt. Paul Loughnane, 380th AMS maintenance supervisor said the program was a definite improvement for the 20-year old aircraft. "Before AMP, the probality for equipment failure on the FB-111A was high. AMP greatly reduced this probality," explained the captain. "Now the chances of a modified FB-111A reaching its target is 96 percent. That's a considerable improvement.
(Photo of FB-111A 67-0159 at McClellan AFB, CA. provided by Mark Sadler.)
The AGM-69A Short Range Attack Missile was developed almost in parallel with the FB-111A program. Boeing undertook studies beginning in 1963 in December 1963 towards a Short Range Attack Missile and coincidentally, the USAF developed the following year SOR-212 resulting in the drafting of Weapons System 104A stipulating such a weapon offering a rocket-assisted range of 100nm. With its head start, Boeing won the contract on 31 October 1966 and live firings (with inert warheads) were underway in the summer of 1969. Initially SRAM equipped B-52s only but studies proved that the FB-111A would be an excellent launch platform because of its more accurate INS and more stable, high speed flight performance. The AGM-69A was a solid rocket-boosted 2,230lb, 14ft long, Mach 3 missile with a maximum stand-off range of up to 100 miles. The million dollar SRAM was a 'smart missile' equipped with a Delco computer and a Singer-Kearfott KT-76 inertial measurement unit (IMU). For attack, the navigator would select stores stations using a new push-button array on his right console, including a special SRAM master control panel to select the delivery mode for that weapon. The first supersonic launch was accomplished on 22 September 1970.
The FB-111A entered the SRAM program when the Category II trials "FB", No.5, flew with polka-dotted test SRAMs. In the summer of 1971, several launches were completed over the White Sands missile Range. An Air Force crew successfully carried out the first "full house" launch of short-range attack missiles (SRAM). Equipped with five SRAMs, two under each wing and one in the weapons bay, FB-111A No.5 was used to carry out the mission at Mach 1.6 and 40,000 feet. Only one actual launch was done, the outboard SRAM on the aircraft's right wing was fired at a side target. The other drops were simulated, with the missiles launched and scored electronically. The launch was the sixth in a series of Category II missions being carried out by the Air Force at Forth Worth. Previous launches were made in an envelope from Mach 1.2 at 1,000 feet to Mach 1.6 at 40,000 feet, and several points in between. As on previous Category II missions, LtCol Ollie Mims was pilot and LtCol Charles Wright, systems operator. The missile was designed to penetrate sophisticated ennemy defenses and could be launched at targets located forward of the aircraft, to either side or even directly behind the aircraft. Nineteen "live" Category I and II launches were made from FB-111A No.5, SRAMs were successfully fired at targets in all these positions and at subsonic and supersonic speeds, and altitudes ranging from on-the-deck to over 40,000 feet.
Called "Bullet Blitz", Category III test operations for the FB-111/SRAM weapon system took place from Pease AFB, NH. The mission was monitored and directed by SAC's 4201st Test Squadron, a tenant unit at Pease AFB. Category III is one of three test stages that any weapon system undergoes before it is considered operational when it is placed under controlled conditions in its daily operational environment. The first task of the the test force was to do Cat.III testing for the FB-111A itself and later expanding it to cover the FB-111A/SRAM combination. Cat.III tests for the "FB" started in 1 October 1971 and were completed by 31 July 1972, requiring 1,812 sorties totaling 8,082 hours of flying time.
Live versions of the AGM-69A joined the FB-111A force in 1973. The 509th BMW joined in Project "Bullet Blitz", a serie of captive flight tests culminating in seventeen launches at the White Sands missile range in New Mexico. The 715th BMS was the first squadron to perform a fully successful live launch on 2 April 1974. Annual SRAM launches were conducted subsequently with a limited stock of missiles, meaning two per year for the whole FB-111A community.Alert FB-111As could carry up to six SRAM but a maximum of four was more typical; two in the weapons bay and two more on the inboard wing pivot pylons (stations 4 and 5). Live versions of the AGM-69A were fitted with a near-common W69 warhead which packed a 200-kiloton yield. SRAM internal carrying was restricted because the Air Force did not buy sufficient quantities of MAU-140 Ejector Rack Adapters to outfit all 76 aircraft.Total number of operational AGM-69A was 1140 from 1975 to 1986 with SRAM inventory peaking at 1471 in 1975. The weapon was withdrawn from FB-111A alert use on 7 June 1990 under the express orders of Defense Secretary Richard B.Cheney.
SRAMs were stored in the Weapons Storage Area located across the active runway. The WSA was manned by the Munitions Maintenance Squadron's Integrated Munitions Maintenance and Storage branch. Six shops made up the IMMS. They were verification and checkout, missile checkout, weapons maintenance, conventional munitions maintenance, equipment maintenance and storage and handling. The IMMS was responsible for maintaining the equipment that electronically verifies the SRAM's electrical systems. The missile checkout section's responsibilities lied in maintaining the entire SRAM fleet and all FB-111A carrier aircraft equipment. The weapons maintenance section consisted of two separate sections, one responsible for the SRAM and the other responsible for the gravity-type weapons. The primary responsibility for the condition of these munitions rested with these sections. The equipment maintenance section maintained the trailers and associated support equipment used to move the weapons. Finally, the storage and handling section was tasked with the movement of weapons.
This view shows FB-111A 69-6510 of the 509th Bomb Wing and some of the ordnance that it may carry. On its wing pylons are 20 BDU-50 500-pound practice bombs. In the front row are, from left: an M-117D 750-pound high-drag bomb, 12 Mark 106 5-pound practice bombs, six Mark 82 500-pound high-drag bombs, 12 more Mark 106 practice bombs and a CBU-85 cluster bomb. In the second row are, from left: B-83 and B-61 nuclear bomb trainers, two AGM-69A SRAM missiles and one more each of the B-61 and B-83 nuclear bomb trainers.
The FB-111A had the ability to carry a variety of stores either in the enclosed weapons bay or at external stations along the wings. The weapons suspension equipment utilized to attach and support the various weapons and stores permitted a selection of weapon arrangements and configurations. The weapons suspension equipment provided the interface between the basic aircraft and the stores it carried. This equipment consisted of pylons and bomb racks. Eight external hard points were provided for pylon attachment. These were numbered 1 through 8 from left to right looking forward. Stations 1,2,7 and 8 were used for fixed pylons while stations 3,4,5 and 6 were used for pivot pylons. To increase its range, the aircraft was able to carry 600-US gallon drop tanks on stations 2, 3, 4, 5, 6 and 7. These tanks were refueled through the aircraft system. Control, selection, monitoring and release of weapons/tanks were accomplished at the stores control panel in the cockpit. Of the eight wing pylons, the four innermost positions were designed to pivot as the wing sweep varied. As a result, externally mounted stores at these stations remained streamlined at all times. A system of mechanical linkages ensured that the pylons always remained parallel to the longitudinal axis of the aircraft as the wing seep changed. Two types of pylons were used: one to carry weapons and one to carry fuse tanks. The weapon pylons accommodated the ejector racks which suspended the stores from the aircraft. Stores and pylons could be jettisoned from these stations. The outermost wing pylon stations were fixed with respect to the wing, therefore stores were streamlined only for a wing sweep angle of 26 degrees. A wing sweep handle lockout control prevented unintentionally sweeping the wings past 26 degrees.
The weapons bay, containing two lateral, symmetrically located stores stations, was situated in the intermediate fuselage section between the nose gear and main landing gear wheel wells. Weapon suspension was provided by universal MAU-12B/A bomb racks. SRAM suspension was provided by AGM-69A ejector racks. The BRU-3A/A multiple ejector rack mated to the MAU-12B/A bomb rack at all pylon stations and provided carriage, individual launch and jettison capability for a maximum of six stores of the same configuration.
The principal armament of the FB-111A was the AGM-69A SRAM, carried in the internal weapon bay and also on stations 3, 4, 5 and 6. Six gravity nuclear weapons such as the B83 and B61 could be carried in the weapon bay and on stations 3, 4, 5 and 6. For a more conventional role, the FB-111A carried up to 24 M-117 on stations 3, 4, 5, and 6 (6 bombs each). As an alternative, CBU-52B/B were carried on the same stations and the aircraft could be armed with AIM-7L "Sidewinder" on stations 4 and 5.
