FGS  Flight Guidance System 
FH  Flight Hours 
FHSS  Frequency Hopping Spread Spectrum 
FIDS  Fault Isolation and Detection System 
FIFO  First Input/First Output 
FIG  Figure 
FIL  Filament 
FIL  Fillet 
FIL H  Fillister Head 
FILG  Filling 
FIM  Fault Isolation Manual 
FIN  Functional Item Number 
FIR  Full Indicator Reading 
FIS  Flight Information Services 
FIX  Fixed 
FL  Flood 
FL  Flow 
FL  Flight Level 
FL  Fluid 
FL  Floor 
Fla.G  Flammable Compressed Gas 
Fla.L  Flammable Liquid 
Fla.S  Flammable Solid 
FLC  Feel and Limitation Computer 
FLD  Field 
FLDK  Flight Deck 
FLEX  Flexible 
FLG  Flange 
FLH  Flat Head 
FLIP  Flight Plan Computation Program 
FLLT  Flashing Light 
FLMPRF  Flameproof 
FLP  Flap 
FLP  Flight Line Planning 
FLS  FMS Landing System 
FLSA  Fuel Level Sensing Amplifier 
FLSCU  Fuel Level Sensing Control Unit 
FLT  Flight 
FLT CTL  Flight Control 
FLTR  Filter 
FLXTO  Flexible Take-Off 
FM  Flight Management 
FM  Flight Manual 
FM  Frequency Modulation 
FM  Fan Marker 
FM  Course from a Fixed Waypoint with a Manual Termination 
FMA  Flight Mode Annunciator 
FMC  Flight Management Computer 
FMCS  Flight Management Computer System (FMC and CDU) 
FMCU  Flight Management Computer Unit 
FMEA  Failure Mode Effect Analysis 
FMGC  Flight Management and Guidance Computer 

FMGEC  Flight Management Guidance and Envelope Computer 
FMGES  Flight Management Guidance and Envelope System 
FMGS  Flight Management and Guidance System 
FMS  Flight Management System (FMCS and AFS sensors) 
FMS  Fuel Manifold Staging 
FMU  Fuel Metering Unit 
FMV  Fuel Metering Valve 
FNA  Final Approach 
FNCP  Flight Navigation Control Panel 
FNSG  Flight Navigation Symbol Generator 
FO  Fully Open 
FO  Flight Order 
FOB  Fuel On Board 
FOC  Fuel/Oil Cooler 
FOCT  Flight Operations Consultation Tool