| Acronym | Meaning |
 | HX | Heat Exchanger |
 | HXIS | Hard X-ray Imaging Spectrometer |
 | HYD | Hydraulic Subsystem |
 | HYD | HYdraulics |
 | HYDROGEN | Purge |
 | HYDROGEN | ReHydrogen Relief |
 | HYG | LHypergolic |
 | HYPACE | Hybrid Programmable Attitude Control Electronics |
 | HZ | Hertz (Cycles Per Second) |
 | I | NTC/0INTC/0Integrated Checkout |
 | I | LAS Instrument Landing Approach System |
 | I | LSP IntegratedLogistics Support Plan |
 | I | DAC Integrated Digital-Analog Converter |
 | I | DAS Integrated Data Acquisition System |
 | I | DPS Interface Digital Processor |
 | I | ECM Induced Environment Contamination Monitor |
 | I | ECO Inboard Engine Cutoff |
 | I | LCCS Integrated Launch Control And Checkout System |
 | I | D&CA Inverter Distribution And Control Assembly |
 | I | FIntermediate Frequency |
 | I-LOAD | Initial-load |
 | I@@PL | Implement |
 | IACS | Inertial Attitude Control System |
 | IAD | Interface Agreement Document |
 | IAD | Interface Analysis Document |
 | IAL | Immediate Action Letter |
 | IAL | International Algebraic Language |
 | IARS | Independent Air Revitalization System |
 | IAS | Impact Assessment Sheet |
 | IAS | Indicated Airspeed |
 | IAS | Integrated Avionics System |
 | IASS | Inverter/ATCS Support Structure |
 | IAT | Integrated Avionics Test |
 | IAV | Inventory Adjustment Voucher |
 | IB | Inboard |
 | IB | Inert Building |
 | IB | Instruction Book |
 | IBF | Internally Blown Flap |
 | IBM | International Business Machines |
 | IC | Intercomputer Communication |
 | IC/ES | Intercommunication/Emergency Station |
 | ICA | Item Change Analysis |
 | ICAO | International Civil Aviation Organization |
 | ICAO | International Civil Aviation Organization |
 | ICAR | Investigation And Corrective Action Report |
 | ICB | Interim Change Bulletin |
 | ICB | Interrupt Control Block |
 | ICC | Intercomputer Channel |
 | ICC | Intercomputer Communication |
 | ICC | Interface Control Chart |