We need some help in obtaining written DoD guidance/examples showing that software needs to be included in Ao calculations and how it is used in the calculations.
We also need a copy of the new reliability standard, ANSI/GEIA-STD- 0009. DAU Web site points to a web site where we have to pay in order to get a copy. We are assuming because the government helped write the standard, there should be a free copy available for government use somewhere.
Yes, software does need to be included in Ao calculations. The referenced DoD Guide for Achieving RAM states: "A mission reliability failure, whether caused by hardware, software, or their interaction, is still a mission failure." For example, a Built-in-Test False alarm that invokes an unscheduled maintenance action is usually considered an operational mission failure.
The referenced Ao equation is generic and should be tailored for each system based on Ao = uptime/(uptime + downtime). Typically, uptime is estimated by a "Mission" reliability parameter. For example: Mean Time-Between-Operational-Mission-Failure (MTBOMF). Using a "Logistics" reliability parameter MTBF may not be appropriate due to non-mission critical failures or redundancy where maintenance can be deferred. The hardware and software faults/failures are captured in the MTBF or MTBOMF parameter. The RAM Guide and the RAM-C Manual both state that failure definitions and scoring criteria should be included in the contract and specification. Traditionally a fault is defined as any non-conformance which requires an unscheduled maintenance action to correct it and a failure is defined as the loss of function. If a failure definition and scoring criteria has not yet been developed, it is recommended that you coordinate this effort with your services Operational Test Agency and Combat Developer since Ao will be evaluated during Operation Testing.
The ANSI/GEIA-STD-0009 is still a non-government standard even though there was DoD participation on the development team. Therefore, contractor and DoD personnel are required to purchase this standard. However, the Adoption Notice does indicate that there may be a DoD discount. The Adoption Notice can be found on the Assist Website:
The following instructions are from the GEIA-STD-0009 Adoption Notice on how to obtain a copy of the standard: Copies of this standard may be obtained from the Information Technology Association of America (ITAA) on line store now under TechAmerica, 1401 Wilson Boulevard, Suite 1100. Arlington, VA 22209, Phone: 703-284-5317, Fax: 703-525-2279,
http://www.techstreet.com/itaagate.tmpl or http://webstore.ansi.org. Check for ANSI DoD discount.