Pilot/Controller Glossary 3/29/18 J JAMMING− Electronic or mechanical interference which may disrupt the display of aircraft on radar or the transmission/reception of radio communications/ navigation. JET BLAST− Jet engine exhaust (thrust stream turbulence). (See WAKE TURBULENCE.) JET ROUTE− A route designed to serve aircraft operations from 18,000 feet MSL up to and including flight level 450. The routes are referred to as “J” routes with numbering to identify the designated route; e.g., J105. (See Class A AIRSPACE.) (Refer to 14 CFR Part 71.) JET STREAM− A migrating stream of high-speed winds present at high altitudes. JETTISONING OF EXTERNAL STORES− Airborne release of external stores; e.g., tiptanks, ordnance. (See FUEL DUMPING.) (Refer to 14 CFR Part 91.) JOINT USE RESTRICTED AREA− (See RESTRICTED AREA.) JUMP ZONE− The airspace directly associated with a Drop Zone. Vertical and horizontal limits may be locally defined. PCG J−1