Instrument Flight Rules 
instrument flight rule 
Increasing Failure Rate 
Interim Final Rule 
In-Flight Refueling 
Institute of Food Research 
Instrumental Flight Rules 
Integral fast reactor 
INTERNAL FUNCTION REGISTER 
International Federation of Robotics 
Image-to-Frame Ratio 
Income Fund Reimbursable 
Income Fund Reimbursement 
In-Flight Refuelling 
inspiratory flow rate 
inspiratory flow resistive 
Instantaneous Frequency Receiver 
Institution File Redesign 
Instrumant Flight Rules 
Instrument Flight Radar 
Instrument Flight Range 
Instrument Flight Regulation 
Instrument Fligth Rules 
Instrument Flying Rules 
Interactive Fax Response 
InterFace Repository 
Interleaved Frame Recording 
International Financing Review 
International Forestry Review 
ion-focused regime