A method of scheduling and controlling asynchronous tasks to provide deterministic behavior in time-partitioned operating systems, such as an ARINC 653 partitioned operating environment. The asynchronous tasks are allocated CPU time in a deterministic but dynamically decreasing manner. In one embodiment, the asynchronous tasks may occur in any order within a major time frame (that is, their sequencing is not statically deterministic); however, the dynamic time allotment prevents any task from overrunning its allotment and prevents any task from interfering with other tasks (whether synchronous or asynchronous).