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 depen- dent 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 14 CFR Part 71.) 

## J 

JET STREAM- A migrating stream of high-speed winds present at high altitudes. 

JETTISONING OF EXTERNAL STORES- Air- borne 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. 

