The Missile Defense Agency (MDA) is in the market for two second-hand Gulfstream G550 business jets to replace its 1970s-vintage Gulfstream IIB test observation platforms. The Gulfstream IIB aircraft regularly deploy across the U.S. in support of missile-testing activities.

The agency’s odd-looking Gulfstream-based High-Altitude Observatory (HALO) aircraft are supported by L3 Aeromet in Tulsa, Oklahoma, and are expected to be replaced before the FAA’s NextGen air traffic control mandates come into effect on Jan. 1, 2020.

The MDA has requested information from potential vendors through a recently published market survey. The agency will not consider aircraft that entered service prior to 2006, or which have accumulated more than 7,000 flight hours. The MDA intended to purchase the first aircraft in 2019 and the second in 2020, but it is now pushing for an initial aircraft contract award in 2018 if possible.