Operations Research: HAwk Replacement Engagement Model (HAREM)

HAwk Replacement Engagement Model (HAREM)

TNO performed air defence studies to support the armed forces during procurement, upgrade and deployment of air defence systems. TNO-FEL developed a set of tools and models for quantitative analysis relevant to those studies. One of those simulation models is HAREM (HAwk Replacement Engagement Model), developed to support deployment analysis and system comparison.

HAREM was originally developed by TNO-FEL to carry out the Hawk upgrade studies for the Royal Netherlands Air Force. These studies had to compare options for an air defence system to replace the Hawk system at the Guided Weapon Battalions. Studies on airbase air defence were later carried out to compare various air defence options and to examine the effect of fire coordination between the guided weapon components at an airbase.

Elements of the HAREM model (figure from the 90's)
Elements of the HAREM model (figure from the 90’s)

HAREM was an air defence model that simulated the engagements between air defence systems and aircraft. The model was split up in five modules, being:

  • database
  • terrain/coverage module
  • scenario planner
  • simulation module
  • output viewer

In HAREM, air defence systems exist of an engagement cycle with sensors, launchers and ground-to-air missiles. The engagement cycle indicates the various processes that an air defence system has to carry out, like detecting a target, identifying a target, prioritising a target, tracking a target, allocating a target, launching a missile, guiding a missile and intercepting a target. These processes are driven by parameters like ranges, reaction times and probabilities, which need to be stored in the database.

HAREM operations
HAREM operations

The effect of terrain limitations was taken into account by using digitised terrain data, for which HAREM has access to the library of the FELCOP (FEL Coverage Program) model in order to import coverage diagrams and terrain information. The planning of air defence deployments had, therefore, to be done in FELCOP.

In the scenario planner aircraft tracks could be created by defining speed and direction of the aircraft from waypoint to waypoint. Attacks of aircraft against air defence systems or other assets could be represented by defining weapon release distances for various types of air-to-ground missiles or bombs. Assets could be created in order to determine the protection capability of air defence systems. Jammers could be on board an aircraft or can be positioned at stand-off locations. The effects of both types of jammers were modelled as range reductions of the search and/or track radars of an air defence system.

An interactive simulation facility graphically presented the development of a scenario over time, showing consecutive engagements between air defence systems and attacking aircraft and/or missiles (air-to-ground and ground-to-air). The user could intervene in the simulation at any time to ask for detailed information. Since HAREM was a stochastic simulation model, simulation runs have to be repeated to get statistically reliable results. In batch mode, these runs could be executed consecutively without human intervention.

All the events that took place within the simulation will be recorded in a file. By making a specified abstract from this file the user could get an overview of all results he/she was interested in.

Apart from studies by TNO-FEL, the model was also used within NATO studies for the Panel Air Defence Weapons (by NAADC).
The flexible and generic modelling of air defence systems in HAREM guaranteed that HAREM could be used for various kinds of air defence studies in which the engagement performance of a single air defence system or a group of air defence systems had to be evaluated. HAREM allows to examine the impact of a particular attack scenario on the air defence systems and to search for the optimum deployment of several air defence systems against a described attack scenario.

The HAREM model was of a high aggregation level, which enabled rapid insight into the effectiveness of ground-based air defence systems, but often with the necessary simplifications. For example, in HAREM the use of countermeasures, tactics and especially Command and Control (C2) were greatly simplified.

In 1994, TNO and the Royal Netherlands Air Force decided to examine how a successor for HAREM could be realised. That effort was nick-named SULTAN (Simulating Universal Land-based Tactical Air Defence Networks). First, a system requirements analysis was performed based on current and future air defence developments and projects. Based upon these requirements, a conceptual model was developed. Given the potentially long development time of SULTAN, it was decided to evaluate a number of internationally known models. After a thorough evaluation, we opted for the Extended Air Defense Simulation (EADSIM) tool. EADSIM was taken into use at the beginning of 1997. The Distributed Interactive Simulation interface of EADSIM could be used as a scenario-generation tool for exercises. EADSIM was used, among other things, for modelling the Patriot air defence system, the Short Range Air Defense (SHORAD) system, and the air defence and command frigate (LCF).