R-NAV
Area navigation
RA
Radio Altitude
RAI
Radio altimeter indicator
RAIM
Receiver autonomous integrity monitoring
RALT
Radar or radio altimeter
RAS
Rectified Air Speed
RCR
Reverse current relay
RCVR
Receiver
RDH
Reference Datum Height for ILS
RDMI
Radio distance magnetic indicator
RDP
Radar data processing system
RDR
Radar
REF
Reference
REL
Relative[disambiguation needed]
RF
Radio frequency
RFI
Radio frequency interference
RFID
Radio Frequency Identification
RHSM
Reduced horizontal separation minimal
RLG
Ring laser gyroscope
RLY
Relay
RMI
Radio magnetic indicator
RNAV
Area Navigation
RNAV
Area navigation
RNG
Range
RNP
Required navigation performance
RNP
Required Navigation Performance
ROC
Rate of climb
ROD
Rate of descent
RPK
Revenue Passenger Kilometers
RPM
Revolutions per minute
RSR
En-route Surveillance Radar
RSVM
Reduced Vertical Separation Minima
RTE
Route
RTKM
Revenue Tonne Kilometre
RVR
Runway Visual Range
RVR
Runway visual range
RVSM
Reduced vertical separation minimum
RVSM
Reduced Vertical Separation Minimum
RWY
Runway
RX
Receiver