JAMMING- Denotes emissions that do not mimic Global Navigation Satellite System (GNSS) signals (e.g., ­GPS and WAAS), but rather interfere with the civil receiver's ability to acquire and track GNSS signals. ­Jamming can result in denial of GNSS navigation, positioning, timing and aircraft dependent functions.

JET BLAST- The rapid air movement produced by exhaust from jet engines.

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 14CFR part71.)

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 14CFR part91.)

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.