International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Due to the rotating mechanism in mechanical disks, they cannot provide the top-level reliability required for operation in harsh military environments. This paper describes three COTS alternatives to mechanical disks: ruggedized mechanical disks, solid-state flash disks and stacked PC Cards. It discusses their cost-effectiveness and aspects such as environmental specifications, endurance and data reliability. It highlights several methods used by flash disks to enhance endurance and reliability, as well as flash pricing and density trends. It presents data security requirements in actual emergency situations, and how flash disks can meet these requirements. It concludes with a feature-by-feature comparison of ruggedized disks, flash disks and stacked PC Cards.