The ability to accurately predict the infra-red signatures of air targets in defined regions of the infra-red spectrum and in known weather conditions is improtant for military applications. The evaluation of the detection and recognition performance for Infra-Red Search and Track systems, surveillance systems, and missile guidance systems relies upon good target emission data. esigners of airframes also require this information in order that signature reduction and stealth techniques can be applied to the design. Making measurements would appear to be the optimum method of obtaining data on targets. However, measurements are notoriously expensive and difficult to make in representative scenarios. The actual intended targets may also be impossible to measure since cooperation is required for meaningful trials to be conducted. BAe Dynamics Division (Hatfield) have been involved in signature measurement and model prediction for many years. This has been primarily in relation to missile guidance applications. For simple tracking and missile systems empirical models are usually regarded as sufficient for basic performance calculation. The extra complexity of future missile systems means that more complex and accurate signature prediction models are required. This includes models which calculate the detailed chemical and thermodynamic properties of the plume for example. Models like these have been implemented and used for performance modelling at Hatfield for some time. However, these models often suffered from the lack of true validation sand were not fully integrated with other model components and did not consider all of the influencing factors in signature prediction (e.g. airframe shielding and reflection). It was of some interest to BAe to discover that a fully integrated and complete model was being developed by NATO Research Study Group AC243 (Panel IV/RSG 6). BAe obtained a working version of the model through the UK panel representative in early 1987 sand were funded by the UK Ministry of Defence (Contract A52b1333) to implement and run the program on a VAX 11/785 computer. Extra routines were written by ourselves to ease data input and output. The model is called NIRATAM (Nato Infra-Red Air TArget Model) and we are currently using Version 1.2.