The interpretation of an OC curve here is the same as that in: It is a plot of the probability of acceptance (passing LAT in this case) on the y axis versus the true penetration probability on the x axis. Shows the OC curves for the DOT&E LAT protocols for the three different lot sizes: 91 to 150 (black), 151 to 500 (red), and 501 to 3,200 (green). The goal of LAT is to assess whether the manufacturer’s helmets continue to conform, and thus the government is expected to assume greater risk at this stage. In comparing LAT and FAT, it is important to keep in mind that the manufacturer has already demonstrated the ability to meet specification requirements via FAT. Resistance to Penetration This section compares the OC curves of DOT&E’s LAT protocol with DOT&E’s FAT protocol and the Army’s original FAT protocol. Further, DOT&E’s FAT protocols are considerably less stringent (higher probabilities of acceptance for the OC curves) than their corresponding LAT protocols.

This is primarily due to the different sample sizes (number of helmets and number of shots) as determined from ANSI standard. The OC curves for the LAT plans for the different lot sizes can vary a lot, indicating that the manufacturer’s and government’s risks can be quite different across lot sizes. This chapter examines the operating characteristic (OC) curves for the Director, Operational Test and Evaluation’s (DOT&E’s) LAT plans and compares them with first article testing (FAT) protocols in the Army’s legacy plans and DOT&E’s plans. The number of helmets in the protocols is determined from an American National Standards Institute (ANSI) standard, and they vary by lot size. A random sample of helmets is selected from the production lot, and the helmet shells as well as hardware are tested according to the LAT protocol. Lot acceptance testing (LAT) is used to ensure that manufacturers continue to produce helmets that conform to contract specifications.

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