Background

Reason For The Mid-Life Update

When the F-16 entered service in 1979, it was expected that the aircraft would be replaced by a successor in 1999. In 1985, Secretary of Defense Van Houwelingen supported the idea of replacing the F-16 between 1995 and 2000 by the French Rafale. The Royal Netherlands Air Force, however, preferred development of an avionics upgrade for the F-16, since the Rafale would not be the technological step forward needed for the next generation of fighters — comparable with replacing the F-104 with the Mirage F-1 instead of the F-16. At that time the RNLAF was convinced the USAF would have an F-16 successor ready by 2005 and that this successor would have features the Rafale would not have.

The first ideas for a major avionics upgrade for the RNLAF were launched in 1985 and were supported by the other three European Participating Air Forces (European F-16 users) in 1986. The project became known as the F-16 Mid-Life Update, or MLU for short.

General Dynamics was not in favor of retrofitting old F-16A/Bs and instead suggested the new Agile Falcon, with enlarged wings and stronger engines. This, however, was rejected by the Royal Netherlands Air Force since it was believed this would be cost prohibitive. The Air Force philosophy was to keep the F-16 with new avionics at the same weight in order to avoid purchasing new 29,000 lbs engines as used in the F-16C/D. This would both save money and would buy enough time to wait for a real new generation of fighter aircraft.

Early Development

Development of the Mid-Life Update started in 1989 with a two year study to the possibilities for an upgrade of the F-16. On May 3, 1991, the MLU development phase was authorized (signature of final partner). Development continued until 1997. On June 15, 1991, General Dynamics was awarded the contract for delivery of the modification kits.

Due to a different political and military situation after the disappearance of the Iron Curtain in 1989, the USAF planned on phasing out their F-16A/Bs in 2000. Therefore, the requirement to upgrade their F-16A/B fleet became irrelevant. In November 1992 the USAF announced their withdrawal from the production phase of the project. European share re-negotiations resulted on 28 January 1993 in a lower number of aircraft to be submitted to the Mid-Life Update (301 vs. the 533 originally planned: Netherlands 172, Belgium 110, Denmark 63, Norway 58, USAF 130).

The letters of acceptance were signed on June 30, 1993. Lockheed Martin was awarded the contract for delivery of the MLU modification kits for European air forces on August 17, 1993. Kit deliveries started in October 1996 and were completed in 1999.

After the MLU the F-16 will not be decommissioned until 2010, although in 1998 the RNLAF was talking about an End-Life Update, indicating the F-16 would not be decommissioned until 2015 or even beyond (!).

Aircraft Structural Integrity Program

The F-16's airframe has been subject to its design loads at a higher number of occurrences at a higher rate than predicted in 1979. This particularly concerned the wing root loads. It also resulted in several unpredicted hair fractures in some of the airframe's bulkheads. Before an aircraft could be offered for MLU modification, its current state of the airframe was examined in an extensive Aircraft Structural Integrity Program, of which of one the most important parts was the Aircraft Structural Life Improvement Program (PACER SLIP).

Note that (hair) fractures are not uncommon in aircraft design. To predict the acceptable number and type of cracks, the aircraft manufacturer used information that reflected the exact capabilities of the aircraft. The F-16 was designed as a light and highly maneuverable aircraft that could withstand 9g and that could last for a minimum of 8,000 flight hours. All data is recorded into a load spectrum that specifies the use of the aircraft — i.e. type of missions — aircraft load and predicted number of landings.

Pacer SLIP

The PACER SLIP program included applying Engineering Change Proposal (ECP) 1910, which included the design and production of doublers for bulkhead reinforcement as well as examining and cold working of pipe-hole connections through the bulkheads if necessary.

In PACER SLIP, approximately ten aircraft a year were modified. The modification was performed by the Royal Netherlands Air Force, in cooperation with Fokker Services B.V. (former Fokker Aircraft Services B.V.), both at Woensdrecht Air Base. After PACER SLIP, the aircraft should be able to last at least until its 5,000th flight hour and can complete its life expectancy of 30 years.

The first aircraft to be examined were the Leeuwarden-based Block-10 aircraft, since these were the oldest ones of the RNLAF. The experience gained from this modification was used by Lockheed Martin when composing the modification kits.

Some of the first aircraft subjected to PACER SLIP went through the PACER UP modification in a later stage, in order to replace a bulkhead that was replaced in a later stage of PACER SLIP.

Each aircraft submitted to the extensive MLU modification was also equipped with the Pratt & Whitney F100-PW-220E engine as a replacement for the F100-PW-200 engine. Engine replacement was estimated at DFL 179 million.

Participating Nations

Several countries participated in the Mid-Life Update; the four EPAF (European Participating Air Forces) countries: The Netherlands (136 aircraft, apart from the LTF and TVI aircraft), Belgium (90 aircraft), Norway (56 aircraft) and Denmark (61 aircraft), the United States (223), as well as Taiwan (150 aircraft). Each of the EPAF nations sent one F-16 to Lockheed Martin in Fort Worth, Texas, as a trial aircraft for the modification. The Royal Netherlands Air Force sent a Block-15 F-16B, aircraft 80-3650.

Due to a different political and military situation after the disappearance of the Iron Curtain in 1989, the USAF planned on phasing out their F-16A/Bs in 2000. Therefore, the requirement to upgrade their F-16A/B fleet became irrelevant. Due to budget restrictions, the US Air Force was forced out of the MLU production phase. However, it remained an equal partner in the development phase. Some modifications were used for their F-16C/Ds.

Taiwan also showed interest in the Mid-Life Update for their F-16s. In 1992 Taiwan forged an agreement with the US to purchase 130 F-16A and 20 F-16B fighters as part of its military modernization efforts. However, the 150 Taiwanese Block-20 F-16A/Bs to be built, were not brought to exactly the same standard as the EPAF post-MLU F-16A/Bs. The Block-20 designation was reserved in the 80s when the manufacturer switched from Block-15 (F-16A) to Block-25 (F-16C). After the Mid-Life Update, the EPAF F-16s will probably be designated as Block-15MLU. The official RNLAF designation for the F-16 is said to be F-16AM and F-16BM, although these designations are not recognized by LMTAS.

In total, 343 EPAF (and 223 USAF) aircraft will be submitted to MLU, of which 136 (excluding the two aircraft modified in an early stage) of the RNLAF (one of the most essential F-16A/B users worldwide, outside the US), of 18 EPAF squadrons in total.

Each of the EPAF countries contributes to the MLU program:

SABCA (supported by Fabrisys and Sonaca) and Fokker Services Woensdrecht set up a joint venture company called CDR (Cooperative Delivery of Retro-kits) that is responsible for the cockpit kits.

In The Netherlands, also Holland Signaal Apparaten, Fokker Papendrecht, and the NLR laboratory are involved in the Mid-Life Update program.

Each aircraft will typically take up to 2,500 man hours, which roughly equals 5 months of labor, but in some cases this may take up to 3,000 man hours. During modification of the production aircraft, approximately 35 aircraft a year will be modified.

Several other current and potential F-16 customers are considering the Mid-Life Update features as well. New production F-16A/Bs with MLU systems are being manufactured and offered as Block-20 aircraft. These aircraft have a Block-50/52 aft fuselage and wing and several other refinements.

Trial, Verification And Installation Aircraft

All five Trial, Verification and Installation (TVI) aircraft of the four EPAF countries and the US were the first ones to be modified by Lockheed Martin Tactical Aircraft Systems (LMTAS), Fort Worth, Texas. The aircraft were completely de-paneled and re-assembled in a later stadium in order to perform all kinds of work, including the replacement of hundreds of wiring harnesses (according to LMTAS, the cockpit alone incorporated one hundred new wiring harnesses).

[Photo: Telegraaf]
TVI aircraft at Fort Worth

The lead time from receipt of an order to delivery of the kits was approximately 32 months.

Once completely re-assembled, the aircraft were transferred to Edwards Air Force Base in order to perform flight tests. After these flights, the Dutch and Norwegian aircraft were moved to Leeuwarden Air Base for further flight tests. These tests included the testing of the new fire control radar system under European weather conditions, AIM-120 integration and air-to-ground modes. In a later stadium, the Belgian TVI aircraft followed. At that time, the software tests commenced.

Lead-The-Fleet Aircraft

The EPAF/US aircraft that were modified during the Mid-Life Update can be divided into four major categories: Block-10 F-16As, Block-10 F-16Bs, Block-15 F-16As and Block-15 F-16Bs.

By means of strict configuration management, the Royal Netherlands Air Force has always kept track of which aircraft has undergone what modification. There have been identified 19 so called sub-blocks, of which 12 are applicable to the RNLAF fleet. Differences between those sub-blocks consist of minor differences in airframe structure, wiring and such.

For each sub-block different modification kits have been developed. Most differences in configuration for the RNLAF were caused by the relatively long time span during which deliveries took place, ranging from 1979 to 1991. Each separate series of aircraft was subject to various extensive modification programs. In order to prevent surprises, the RNLAF has thoroughly selected 9 aircraft from different sub-blocks as Lead-The-Fleet (LTF) aircraft. Those LTF aircraft were the first ones to be modified by the RNLAF and Fokker.

DT&E / OT&E

Initial F-16MLU Development Test & Evaluation (DT&E) took place at Edwards AFB, USA, during which phase the avionics integrity was checked and evaluated. Imperfections have been corrected by Lockheed Martin (LMTAS) or Norhtrop Grumman (formerly Westinghouse/WEC).

The Operational Test & Evaluation (OT&E) at Leeuwarden AB and the Development Test & Evaluation at Edwards AFB were conducted simultaneously. The reason for this was that the European air forces demanded to be operational with the F-16 MLU in 1998.

At Leeuwarden AB, the OT&E team was temporarily integrated into 323/TACTESS Squadron as an additional flight.

Software Development

The first operational Operational Flight Program (OFP) for the F-16 MLU was the M1 tape, that became available around March 1998. The successor of that tape will be M2, expected to be available in 2000. Until then, all production MLU aircraft will use the 3D test tape (October 1997). The M1 software was developed in four stages, each with its own interim software tape (Flight Test Tape (FTT) 1 through 4) each concerned with different aspects.

• FTT-1 DT&E
  • Radar performance evaluation
• FTT-2 DT&E
  • Weapon modes Air-Air and Air-Ground
  • Navigation (INS and GPS)
  • Basic MMC core functions
• FTT-3 DT&E
  • Datalink
  • IFF interrogation
  • Horizontal Situation Display
  • DTS integration
  • Color screen implementation.
• FTT-4 DT&E
  • "Clean-up" tape, intended as correction to imperfections found in earlier phases.

In October 1997, both DT&E and OT&E used OFP Tape 4.

Before MLU, F-16 computer software had been written in the Jovial standard computer language. With the MLU all software was rewritten in the ADA language which — according to the MLU project manager for the F-16 Combined Test Force (CTF) — will reduce future software development. Another difference is that F-16A/B software for the Fire Control Computer originated from the USAF's Ogden Logistics Center (OLC), while the new MLU software was written by Lockheed Martin.

Just like the OFP upgrades of the conventional F-16 a new Operational Flight Program upgrade is expected every three years.

With each new software tape, new capabilities will be introduced:

• M2 (expected to be available in 2000):
  • Automatic Target Hand-off System (ATHS)
  • Integration of anti radiation missile capability
  • Integration of target designator system
  • Further implementation of the Digital Terrain System
• M3 (expected to be available in 2003):
  • Integration of capability for GPS controlled weapons
  • Introduction of Helmet Mounted/Cueing Sight
  • Introduction of advanced short-range missile, as a replacement for the current Sidewinder
• M4 (expected to be available in 2005)

On average, a new software version is expected every three years.

See Developments: MMC Software Upgrade.

M1 Software

The first version, M1, was developed in 1995, by Lockheed Martin Aeronautocs Company. Testing took place at the F-16 Combined Test Force at Edwards Air Force Base. During 1996-1997 tests took place at Leeuwarden Air Base. The M1 software became available at squadron level at the beginning of 1998.

M2 Software

The second version, M2, was available in 2000. From June 19 2000 on, the M2 OT&E was commenced at Leeuwarden Air Base. Over 80 improvements and new features were implemented, of which some of the most important are:

• Integration of the BAe Atlantic navigation pod with laser spot tracker (Netherlands).
• Integration of the Raytheon AGM-88 HARM missile (Netherlands, Denmark). The Netherlands canceled plans for the AGM-88, Denmark postponed a decision.
• Integration of the digital Automatic Target Hand-off System.
• Introduction of a more user friendly fire control presentation for the AIM-120 (changed symbology for the Dynamic Launch Zone).
• Increase of the maximum number of aircraft with which the IDM can communicate in an intra-flight datalink from four to eight.
• Introduction of the feature to modify the colors of tactical symbology of the Multi-Function Displays.
• Increase in accuracy of the Digital Terrain System by linking the system to other navigational systems in the F-16.

With M2 software MLU F-16s can be used in the USAF Sure Strike concept. Using a datalink between the aircraft and a Close Air Support Integrated Targeting System, data can be exchanged between the aircraft and the Forward Air Controller or Forward Observer. OIP Sensor Systems (daughter of Delft Instruments) was granted an exclusive license to sell Sure Strike technology. The FAC uses a GPS system and a computer and "illuminates" a target. Information is then sent to the aircraft, where it appears on the HUD, surrounded by a target designation box.

The drawback of the USAF Sure Strike technology — using a "nine-liner" — is that it can not handle the NATO standard message format. It is possible to exchange data with other IDM equipped aircraft, such as the USAF Block-40 F-16s, AH-64 helicopters, and JOINT STARS. The number of aircraft that can be part of the same intra-flight datalink, has been increased from 4 to 8.

M2 software is not expected to become available for the Unit Level Trainers until 2001.

M3 Software

The M3 software — already completely defined — is expected to become available in 2003. Introduction of this version will also include a hardware modification to the aircraft's airframe to facilitate installation of the Link 16 datalink hardware. With Link 16 links can be established with other American and British aircraft, ships, and ground-based stations.

The Modular Mission Computer will be extended with a new circuit board, used by the USAF in their MMC-5000. The European MMC will then be designated MMC-3051.

Other improvements with M3 include:

• Integration of the Helmet-Mounted Cueing System (HMCS) — ordered by Denmark.
• Preparation for new air-to-air missile types, such as the AIM-9X, and IRIS-T.
• Preparation for new American weapons, such as JDAM, JSOW, and WCMD.

Airframe modifications will be performed under the Falcon STAR program.

M3 development is expected to commence in 2000. In 2001, M3 DT&E will be conducted from Edwards Air Force Base, followed by a European DT&E in 2003. The software is expected to become available at squadron level in January 2004.

M4 Software

One and a half year after the M3 software, M4 will be expected, with software becoming available to the squadrons in 2005. The full definition of the software is expected to be completed in 2000.

Avionics Upgrade

Most of the avionics installed during the MLU, is existing off-the-shelf hardware that was modified for use in the F-16. The Modular Mission Computer, however, was designed especially for the F-16; this can be considered the most important of the computers of the F-16. The most significant changes were:

• Modular Mission Computer for fire control, stores management, and HUD processing, adding Helmet-Mounted Display features.
• Data Entry Cockpit Interface Set, integrating communication and navigation.
• Multifunction displays, replacing existing displays.

Though the US Air Force dropped out of the MLU production segment, all along it planned to incorporate the new Modular Mission Computer (MMC) into over 200 of its Block-50/52 and 450 Block-40 aircraft and after funding was approved also the color Multi-Function Display set.

You can read more about the avionics upgrade in Upgraded systems.

Since the same MMC will be used in USAF Block-50 aircraft and the upgraded European MLU F-16s, hardware will be common to both types. However, the USAF MMC version will be incorporated with some unique software enhancements due to a wider range of weapons that is not in the European inventory. After the MLU, it will be the first time the European F-16s will be ahead of the USAF F-16s in terms of sophistication and capability, according to Lockheed Martin.

The avionics that is common with Block-50 after the MLU relates to:

• Wide-angle HUD
• Up-front controller
• Side stick controller
• Digital Terrain System

The improvements that are unique to the MLU relate to:

• Color Multi-Function Displays
• Advanced IFF
• Improved Data Modem
• Penguin missile capability
• Miniaturized GPS
• Electronic Warfare Management System
• APG-66(V)2 — unique to EPAF

MLU Schedule

The Leeuwarden based 322 squadron was the first squadron to switch to the MLU F-16. The upgraded aircraft was officialy presented on June 11, 1998. Next, the Twenthe based 315 Squadron went through the process of conversion with work being completed at the end of 1998. After that, the other squadrons will follow.

Operational Consequences

Pilot Training

The Mid-Life Update changed pilot training. Originally, the F-16 served in the CWI (Clear Weather Intercept) role for visual interceptions and ground attacks under daylight conditions. With the basic F-16A night flying was done mainly for navigation training. However, after the Mid-Life Update and the introduction of Forward Looking Infrared and Night Vision Goggles around 1999 this became a significant part of pilot training. Rather than an increase in low level flying training in Goose Bay for example, flight time shifted to cover more night operations.

All F-16 squadrons currently operate in the so called swing role concept, which means that each squadron is capable of at least two tasks (Clear Weather Intercept, Air-to-Ground, or Reconnaissance). The MLU and new weapons are so versatile however, that the pilot will be unable to keep up with all tasks. Therefore, task specialization will be introduced within the squadron — i.e. a squadron will be more capable of one task than of another. This concept was first introduced on a small scale by the RNLAF detachment in Villafranca (Italy) during operations over former Yugoslavia. A limited number of AGM-65D missiles were leased from the USAF pending delivery of the AGM-65G in 1998. Only a small number of pilots in Villafranca were qualified for this missile.

Furthermore, the original Operational Flight Trainers ("flight simulators") at the Main Operating Bases were phased out between 1997 and 2000. The MLU training concept is based on Unit Level Trainers. A ULT is a modular training unit suited for basic and safety of flight procedures. Each of the squadrons has one ULT at its disposal.

SEAD Capability

It is likely that after the Mid-Life Update the RNLAF F-16s will receive limited capabilities for Suppression of Enemy Air Defense (SEAD) operations. There were serious plans for purchasing a new anti-radiation missile in 1998. The decision was unclear as a choice was to be made between the Matra BAe Dynamics ALARM and the Raytheon/Texas Instruments AGM-88 HARM. Usage of the ARM missile on the post-MLU F-16 would require a change in the software. This change is being implemented in the current software in negotiation with all other MLU partners.

Acquisition of a SEAD capability by the RNLAF is a result of the NATO planning process. In 1998 about 30 squadrons were being offered to NATO's Reaction Force (RF). Of these, 13 operated the F-16 and only two had the disposal of SEAD capabilities: the United States and Germany. In total, 9 countries have been asked to acquire a SEAD capability.

MLU: Worth All Effort And Money?

Because of the F-16's unpredicted heavier airframe load in the Royal Netherlands Air Force the aircraft's airframe needed to be overhauled regardless of the Mid-Life Update to allow the airframe to complete 3,500 flight hours. Keeping the aircraft operational until its 5,000th flight hour made the costs involved in the airframe repair / overhaul affordable and acceptable, making expensive airframe "re-inspections" unnecessary. The costs of the airframe repair / overhaul only formed a quarter of the costs involved in the Mid-Life Update.

The cost of the Aircraft Structural Improvement Program (ASIP) resulted in increased operational capabilities as well as an increased life expectancy for the F-16 aircraft. This cost was lower than the price of a new aircraft. After the F-16 Mid-Life Update modernization program the F-16 can again compete with the most advanced fighters of today's world.

An increase of both technical and economical life expectancy justified the cost for the Mid-Life Update program.

F-16 Successor

In 1997, studies were conducted regarding a possible successor for the F-16. In April 1997, The Netherlands signed the Joint Strike Fighter Requirements Validation Memorandum of Agreement with the United States, offering the RNLAF the status of "limited cooperative partner". Together with Italy these are level 2 partners. The American Joint Strike Fighter (JSF) is the most likely F-16 successor, with a possible order for 150 aircraft.

Norway, Denmark, Canada, Australia, and Turkey also showed interest in the project and are level 3 partners. With an investment of US$250 million the United Kingdom plays a more significant role as a level 1 partner.