In October of that year, the Altus II was flown in an Atmospheric Radiation Measurement (ARM-UAV) study in Oklahoma conducted by Sandia National Laboratories for the Department of Energy.

After major modifications and upgrades, including installation of a two-stage turbocharger in place of its original single-stage unit, a larger fuel tank and additional intercooling capacity, the Altus II returned to flight status in the summer of 1998.

The goal of its development test flights was to reach one of the major Level 2 performance milestones within NASA's ERAST program: to fly a gasoline-fueled, piston-engine remotely piloted aircraft for several hours at an altitude at or near 60,000 feet.

Hard-to-measure properties of high-level cirrus clouds that may affect global warming were recorded using specially designed instruments while the Altus flew at 50,000 feet altitude off the Hawaiian island of Kaua'i.

Data from the study will help scientists better understand how these dual roles of clouds in reflecting and absorbing solar energy work, and build more accurate global climate models.

In September, 2001, Altus II served as the UAV platform for a flight demonstration of remote sensoring and imaging capabilities that could detect hot spots in wildfires and relay that data in near-real time via the Internet to firefighting commanders below.