Allocation of reliability requirements: a new approach

The author presents a formula to combine two methods to allocate top-level system requirements to lower levels (Equal and ARINC) so as to maximize their strengths and minimize their weaknesses. The equal approach allocates requirements equally to the next lower level without regard to complexity. The ARINC method allocates requirements to the next lower level weighted by the complexity for that element. This approach takes complexity into consideration, but provides little incentive to make the complex elements better. The formula developed by the author combines the two methods and allows the use of a single variable to weight the two methods according to the users´ needs. Additionally, a safety margin is incorporated to allow for design changes