IRQ  Interrupt Request 
IRR  Internal Rate of Return 
Irr.M  Irritating Material 
IRS  Inertial Reference System 
IRS  Inspection Report System 
IRU  Inertial Reference Unit 
ISA  Inertial Sensor Assembly 
ISA  International Standard Atmosphere 
ISAMI  Improvement of Structure Analysis through Multi-disciplinary Integration 
ISB  Inter-System Bus 
ISDN  Integrated Services Data Network 
ISDU  Inertial Sensor Display Unit (IRS) 
ISG  Instrument Symbol Generator Unit 
ISIS  Integrated Standby Instrument System 
ISM  Illumination Sensor Module 
ISO  International Standardization Organisation 
ISOL  Isolation 
ISP  In-Service Problem 
ISP  Integrated Static Probe 
ISPSS  In-Seat Power Supply System 
ISPSU  In-Seat Power Supply Unit 
ISPU  In-Seat Power Supply Unit 
ISRO  In-Service Reportable Occurrence 
ISS  Inertial Sensor System 
ISU  Inertial Sensor Unit 
ISWL  Isolated Single Wheel Load 
IT  Interruption 
IV  Isolation Valve 
IVASEB  Integrated Video and Audio Seat Electronic Box 
IVCP  Integrated Value Creation Project 
IVS  Inertial Vertical Speed 
I/I  Inspection/Interval 
I/O  Input/Output 
I/P  Intercept Profile 
I/P  Intercept Point 
I/P  Input 
JAA  Joint Aviation Authorities 
JAM  Jammed, Jamming 
JAMG  Jamming 
JAR  Joint Aviation Requirements 
JB  Junction Box 
JCT  Junction 
JEMTOSS  Jet Engine Maintenance Task Oriented Support System 
JEP  Jeppesen 
JFGW  Jettison Final Gross Weight 
JIC  Job Instruction Card 
JID  Jeppesen Inflight Database 
JITX  Jeppesen Integrated Tool Kit X 
JK  Jack 
JOG  Joggle 
JTSN  Jettison 
JUNCTN  Junction 
K  K 

K  Subgrade Reaction Modulus 
K  Degrees Kelvin 
KA  Knowledge Acquisition 
KBD  Keyboard 
KB/s  Kilo Bits per Second 
KCCU  Keyboard and Cursor Control Unit 
KE  Knowledge Engineering 
KeV  Thousand Electron Volts 
KFS  Kaspersky File System 
kg  Kilogram 
kg/m3  Kilograms/Cubic Meter 
KHZ  Kilohertz