IDG  Integrated Drive Generator 
IDP  Integrated Data Processing 
IDU  Interactive Display Unit 
IEC  International Electrotechnical Commission 
IEEE  Institute of Electrical and Electronic Engineers 
IES  Industrial Evaluation Sheet 
IETF  Internet Engineering Task Force 
IF  Intermediate Frequency 
IF  Initial Fix 
IFE  In-Flight Entertainment 
IFEC  In-Flight Entertainment Center 
IFES  In-Flight Entertainment System 
IFP  In-Flight Performance Computation Program 
IFPA  InFlight Performance Application 
IFR  Instrument Flight Rules 
IFSD  In-Flight Shut Down 
IFTB  In flight Turn back 
IGB  Inlet Gear Box 
IGGS  Inert Gas Generation System 
IGN  Ignition 
IGV  Inlet Guide Vane 
IIPD  Illustrated Initial Provisioning Document 
ILLUM  Illumination 
ILLUMD  Illuminated 
ILS  Instrument Landing System (LOC and G/S) 
IM  Inner Marker 
IMA  Integrated Modular Avionics 
IMC  Indirect Maintenance Cost 
IMM  Immediate 
IMPACT  Improvement Manufacturer Program for Airbus Customer Training 
IMU  Inertial Measurement Unit 
in  Inch 
IN  Inch 
IN-LBS  Inch-pounds