This paper addresses the problem of specifying properties of aircraft separation assurance software, and verifying these properties at runtime. In particular, we target AutoResolver, a large, complex air-traffic control system that predicts and resolves aircraft loss of separation. In previous work, we developed a light-weight testing environment for AutoResolver. Our work contributed a wrapper around AutoResolver, which enabled the automated generation and fast execution of hundreds of thousands of tests. The focus of the work presented here is in specifying requirements for AutoResolver, in ensuring the generation of test cases that cover these requirements, and in developing a runtime infrastructure for automatically checking the requirements. Such infrastructure must be completely transparent to the AutoResolver code base. Our work combines test-case generation and runtime verification in innovative ways in order to address these challenges. The paper includes a detailed evaluation and discussion of our verification effort.