| Acronym |
Definition |
| Ramp Weight |
maximum permissible weight of an aircraft. |
| RAPID |
change expected to take place in thirty minutes or less, term used in met reports. |
| RAS (1) |
Rectified Airspeed. Indicated airspeed corrected for instrument position error. |
| RAS (2) |
Radar Advisory Service. |
| RASA |
Radar Advisory Service Area. |
| RCL |
Runway Centre-Line. |
| RBI |
Relative Bearing Indicator, displaying information from the ADF. |
| RDO |
Radio. |
| RIS |
Radar Information Service. Provided to notify pilots of conflicting traffic outside regulated airspace, but offering no avoiding action. |
| RMI |
Radio Magnetic Indicator. A navigation aid which combines DI, VOR and/or ADF display and will indicate bearings to stations, together with aircraft heading. |
| RMK |
Remark(s). |
| RMU |
Radio Management Unit. |
| Rnav |
Area navigation. |
| RON |
Remain Over Night (night-stop). |
| RT |
Radio Telephony. Voice communications, as opposed to WT, wireless telegraphy. Also named RTF. |
| RVR |
Runway Visual Range, a horizontal measurement of visibility along a runway. |
| RWY |
Runway. |
| RX |
Receiver. |
