An Operational Assessment (OA) is an evaluation of operational effectiveness and operational suitability made by an independent Operational Test Agency (OTA), with user support as required, on other than production systems. 
The focus of an OA is on significant trends noted in development efforts, programmatic voids, risk areas, adequacy of requirements, and the ability of the program to support adequate operational testing. An OA may be conducted at any time using technology demonstrators, prototypes, mock-ups, Engineering Development Models (EDM) or simulations, but will not substitute for an Initial Operational Test and Evaluation (IOT&E) required for the Full-Rate Production Decision Review (FRPDR). 
The Program Manager (PM) should request an Operational Assessment (OA) of weapons system components and/or system level EDMs during the Engineering, Manufacturing and Development (EMD) Phase to meet exit/entrance criteria and to help evaluate system performance and assess technical risk before Milestone C.
Early Operational Assessments
A PM can request the OTA conduct an Early Operational Assessments (EOA) of prototype items of equipment with the purpose to help the identify and reduce program risk before program initiation. EOS’s are conducted primarily to forecast and evaluate the potential operational effectiveness and suitability of the weapon system during development. EOAs start during Concept Refinement (CR) and/or Technology Development (TD) may continue into system integration. 
AcqLinks and References:
- Defense Acquisition Guidebook (DAG) – Chapter 9 & 11
-  DAU Test and Evaluation Management Guide – Chapter 11.4.1 – Jan 2005