When the F-16 entered service in 1979, it was anticipated that the aircraft would be replaced by a successor by 1999. However, this did not materialize, and the F-16 was forced to soldier on for much longer than anticipated. In order to maintain the same level of effectiveness for the F-16 fleet, an extensive modernization program was developed, which came to be known as the Mid-Life Update, or MLU.
In the mid 1980s, faced with an improving Soviet threat, numerous European F-16A/B Block 15 aircraft were scheduled to go through a Mid-Life Update (MLU) program. The MLU program was designed to bring the Block 15 aircraft up to the standards of the Block 50/52 F-16C/D, in particular to give them the capability of carrying and launching BVR weapons such as the AIM-120 AMRAAM, together with the ability to carry out precision weapons delivery missions at night and in adverse weather.
The international MLU agreement was signed on May 3, 1991, with the USA, Belgium, Denmark, the Netherlands, and Norway all being participants. The USA had originally planned to upgrade some of its F-16A/Bs as part of the MLU program, but because of the end of the Cold War and the general reduction in the US fighter force, it withdrew from the program in 1992, but agreed to continue to support the MLU and to carry out test flying for development. The European MLU pact had to be revised downward to reflect the new fiscal constraints arising from the end of the Cold War.
The MLU aircraft are powered by the Pratt & Whitney F100-PW-220 turbofan, rated at 14,590 lb.s.t dry and 23,770 lb.s.t with afterburning.
The F-16s had been subject to more heavy loads than had been initially predicted, and several hair cracks had begun to appear is some of the airframe's bulkheads. This lead to an extensive airframe repair and overhaul, raising the life expectancy of the aircraft. The air inlet structure of the Block 10 aircraft were modified so that hard points could be installed.
The MLU aircraft are all re-equipped with the Westinghouse AN/APG-66(V)2 radar. This more advanced unit has an improved transmitter and low-power RF section, and a new signal data processor. The system has a 25-percent longer range, and can cary out multiple missile engagements. It is compatable with BVR missiles such as SkyFlash, AIM-7 and MICA as well as the AMRAAM. It offers a 25 percent improvement in detection and tracking range, enhanced air-to-ground mapping modes, an enhanced Doppler Beam Sharpening mode, and enhanced air-to-ground and ground mapping modes.
The Hazeltine APX-111(V1) Advanced IFF system is indtalled, with four antennae mounte on the upper forward suselage in front of the canopy. This is the most notable exterior hange of the MLU.
There is a new heads-up display built by GEC Marconi., plus a new Multi-Function Display set. These will increase the pilot's situational awareness.
An electronic warfare management system developed by Terma Eletronik AS of Denmark provives centralized EW control. A GPS receiver is installed for accurate position, velocity, and time to support navigation, steering, and weapons delivery. There is a Digital terrain System to provide precise navigation in conjunction with the GPS system.
The cockpit layout is simliar to that of the F-16C/D Block 50/52 aircraft
The three computers of the original F-16 (the fire-control computer, the stores management computer, and the HUD controller) are replaced by a single Texas Instruments (now Raytheon) modular mission computer, which is key to providing new capabilities suh as sensors and wepons, improved, pilot-vehicle interface, and pilot aiding.
The gauge cockpit instruments are replaced by electronic instruments using full-color LCD displays. The original HUD is replaced by a wide-angle GEC-Marconi unit similar to that fitted to the Block 50/52 F-16C/D. The cockpit and display generator are compatible with night-vision goggles. The cockpit and display generator also have provisions for helmet-mounted displays, but HMD technology is not incorporated into the system itself.
The MLU carries the Hazeltine AXP-113(V) IFF system, with a quadruple set of interrogator antenna mounted ahead of the windshield. This system is not carried in USAF F-16Cs.
A fully-integrated Global Positioning System (GPS) is installed, and a digital terrain system (DTS) is fitted. The DTS is built into the OSC/Fairchild Defense Data Transfer Unit (DTU). The DTU allows the pilot to load mission data into the system via a plug-in cartridge. The DTU cartridge has a processor which incorporates a terrain profile matching algorithm. DTS determines the exact position of the fighter by matching the changing radar altimeter readings to the terrain profiles stored in the database. DTS provides terrain-following information to the HUD, and DTS data provides the aircraft's pilot with a waring if the aircraft is in any danger of striking an obstacle. GPS and INS provide two independent check on the health of the DTS. The DTS also provides passive ranging to ground targets.
The MLU also provides chin pylons for FLIR and targeting pods. The basic MLU does not provide an active onboard electronic warfare system, but the Terma EW system can support active jamming and missile approach warning systems.
General Dynamics (now Lockheed Fort Worth) was awarded a contract to build the MLU kits. One F-16 from each of the USAF, Danish, Dutch, and Norwegian air forces was delivered to Lockheed Forth Worth in September 1992 to act as a prototype for conversion under the MLU program.
The first of five prototype conversions flew on Apr 28, 1995, and installation of production conversion kits began in January 1997. 325 kits were ultimately produced (72 for Belgium, 61 for Denmark, 136 for the Netherlands, and 56 for Norway) Those F-16A/B receiving the MUL were redesignated F-16AM/BM. In 2001, Portugal announced that it also was considering upgrading its F-16s with MLU. In 2005 Jordan joined the program, and in 2010 Pakistan also signed up. In recent years, Chile, Jordan, and Pakistan have purchased surplus Dutch and Belgian F-16AM/BM aircraft.