Acronyms: H

Acronym	Name
HQ	FAA Headquarters
HRD	Home routing domain
HRR	Helicopter Rapid Refueling Procedures
HS-DSAD	High speed digital service access device
HSD	High-speed data
HSI	Horizontal Situation Indicators
HSI	Horizontal situation indicator
HSIT	Hardware and software integration test
HSL	Heading select
HSPD	Homeland Security Presidential Directive
HSR	High stability reference
HSRP	Hot standby routing protocol
HTC	Highest two-way channel
HUD	Head-Up Display
HUD	Head-up display
HUD	Heads Up Display
HUD	Housing and Urban Development
HUL	Horizontal uncertainty level
HUMINT	Human intelligence
HUMS	Health & Usage Monitoring Systems
HUMS	Health and usage monitoring system
HVAC	Heating, Ventilating, and Air Conditioning
HVPS	High voltage power supply
HVT	High-value target
HWAS	Hazardous In-- Flight Weather Advisory
HWAS	Hazardous In-Flight Weather Advisory
HWCI	Hardware configuration item
HX	Heat exchanger
HYD	Hydraulic
HYDIM	HYD interface module
Hz	Hertz