Currently aircraft system test benches are often specific and proprietary, designed and configured for a dedicated system under test (SUT). Today no standards for configuration, data communication and data exchange formats are available for avionic test benches. This leads to high test bench development costs and redundant activities between aircraft system suppliers and air framers. In the case of obsolescence issues for test system components it is very costly to replace the respective parts as a high integration and reconfiguration effort is required. In the scope of an R&T project, involving several test system suppliers and aircraft system suppliers as well as Airbus as an aircraft manufacturer, a generic and modular architecture for an open test environment is under development. The goal of virtual and hybrid testing project is to prepare a set of open standard for the interfaces to this architecture. The architecture allows a seamless transition from Model In The Loop (MIL) via Software In The Loop (SIL) to Hardware In The Loop (HIL) testing. This open architecture is an enabler for the interconnection of System Test Benches provided by different suppliers to Multi-System- and Functional Test Benches. Leveraging automated configuration concepts, automated simulation integration approaches as well as a centralized "Control and Status & Health Monitoring" concepts allows increasing test flexibility and efficiency. Test system functions like Failure Injection, Test Data Recording, Test Data Replay are also considered in the standardized interface and allow a Real-Time data exchange between the modules. The paper will give an overview about the modular architecture and the proposed APIs. In addition, the project's agile development approach will be illustrated.