Release
The term release can be used in the phraseology for the co-ordination of a transfer of control between ATS units/sectors, by which the transferring unit/sector indicates the conditions under which the receiving unit/sector may assume control of the flight.
Reliability
1- The probability that a component is ready for use during its period of availability. A measure of consistency or dependability or repeatability. The results of a particular testing session should be replicated if the same individuals were re-tested under similar conditions. Reliability of a test means that the test behaves the same way under a variety of circumstances (e.g. the test yields similar results when different persons administer it, when the test is administered on different occasions, when alternative forms of the test are used, etc.).
1.
 The probability of failure-free performance under stated conditions

2.
 The probability that an item can perform its intended function for a specified interval under stated conditions. For redundant items, this defines the reliability of the main and standby items as a whole.

2- The probability of performing a specified function without a failure under given conditions for a specific period of time.
Reminder
A message sent to Controllers to remind them of previously planned actions. Reminders are of the following types: change of control frequency reminder; manual co-ordination reminder; start of manoeuvre reminder; area reminder; controller specified reminder.
Reminder Lead Time
A monitoring criteria parameter, that specifies the time at which a reminder is to be issued. The parameter is a relative time offset that is applied to the time that the associated reminder event occurs (or is predicted to occur). This parameter may be positive or negative leading to reminders being issued either before or after the occurrence of the associated reminder event.
Reminder Removal Interval
A monitoring criteria parameter that specifies the duration a reminder is extant following a receipt of a corresponding controller acknowledgement.
Remote Communications Outlet
An unmanned communications facility remotely controlled by air traffic personnel. RCO's serve FSSs. An RCO may be UHF or VHF and will extend the communication range of the air traffic facility.
Repeatable Accuracy
The accuracy with which a user can return to a position whose co-ordinates were measured at a previous time with the same navigation system.
Repetitive Flight Plan (RPL)
A plan related to a series of frequently recurring, regularly operated individual flights with identical basic features, submitted by an operator for retention and repetitive use by ATS units.
Reply
The pulse train received at a SSR ground station as a result of successful SSR interrogation.

 
Report of the RTCA Board of Directors' Select Comm