C-18 (ARIA) takes off on its first flight at Wright-Patterson AFB, Ohio, following its conversion from a Boeing 707-320. The C-18 is the US military designation for the conversions of the 707-320B series. ;C-18A: Eight second-hand (former
American Airlines) 707-323Cs bought as crew trainers for the EC-18Bs, four later converted to EC-18B, two converted to EC-18D, one to C-18B; one was not taken into service and was used for spares. ;C-18B: One C-18A modified with instrumentation and equipment to support the
Military Strategic and Tactical Relay System (MILSTAR). ;EC-18B: Four C-18As modified alongside
examples of the C-135 for Advanced Range Instrumentation Aircraft (ARIA) missions in support of the
Apollo space program. ;EC-18C: Original designation for two prototype J-STAR aircraft, later redesignated E-8A. ;EC-18D: Two C-18As modified as a Cruise Missile Mission Control Aircraft (CMMCA). ;707:
IRIAF operates 707 Tankers and Transports. ;707 Re’em: The
Israeli Air Force operates an undisclosed number (sources suggest 7) of converted Boeing 707s with flying booms in
120 ("Desert Giants") Squadron. Israel's fleet are former civilian aircraft adapted for military uses such as aerial refueling of fighter jets and transport. Able to carry 20 extra fuel tanks while modified for aerial refueling, the Re’ems can be adapted to carry passengers as well as cargo such as military equipment and ammunition. Following the outbreak of the
COVID-19 pandemic in 2020, the planes have also been used to carry medical equipment. ;707T/T: The 707 Tanker/Transport.
Italy purchased and converted four 707s, two to tankers and two to a straight freighter. No 707 tankers remain operational as of 3 April 2008. Also,
Omega Aerial Refueling Services operates K707 tankers for lease. ;KE-3A: The
Royal Saudi Air Force purchased eight E-3 airframes configured as aerial refueling tankers. ;
Condor: Airborne Early Warning, Command and Control (AEWC&C) aircraft developed in conjunction with Israel Aircraft Industries (IAI) using a former Lan Chile aircraft. ;CT-49A/707TCA: Three ex-Sabena airliners converted to TCA (Trainer Cargo Aircraft) in 1989 to support the NATO NAEWF E-3A training and air transport/cargo based on Boeing 707-320B. The aircraft were capable of making dry hookups with the USAF Flying Boom air-to-air refuelling system for training of pilots that were new to NAEWF, but also served as cargo/passenger transport. The two oldest/highest time 707s were replaced by two former Luftwaffe 707s in 1999. NAEWF withdrew the TCAs in 2011. ==Operators==