Availability
1- Requirements for SDPS : (as defined in Eurocontrol Radar Surveillance in En-Route Airspace and Major Terminal Areas Standard). The availability requirements are expressed by : maximum outage time due to any given failure(5-10 mins); cumulative outage time due to all failures over a period of one year(to 9 hours / year); outage time due to scheduled actions (agreed by the users on a case by case basis).
2- The availability of a navigation system is the percentage of time that the services of the system are within required performance limits.
3- With respect to a component, period during which the component is expected to be available (excluding scheduled down times).
The property of an item to be accessible and usable upon demand by an authorised entity in a determined percentage of a stated period of time (operational hours) relevant to the requirements of the item.
Average Air Traffic Flow Management
Total minutes of departure delay/Total number of flights where total minutes of departure delay is accumulated over all flights.
Average Air Traffic Flow Management Delay per delayed flight
Total number of delayed flights/Total number of flights. Departure delay in relation to the number of flights that are delayed is a measure of the seriousness of delay to an aircraft operator and its passengers. Short delays can be absorbed quite easily but as the delay grows disruption will increase.
Aviation Binary Phase Shift Keying
A type of digital modulation selected for use in AMSS for channel rates not greater than 2400 bits/s.
Aviation Quadrature Phase Shift Keying
A type of digital modulation selected for use in AMSS for channel rates greater than 2400 bits/s.
Aviation Safety
The entire issue of safety as applied to aircraft, on the ground and especially when airborne.
Aviation VHF Packet Communications
The AVPAC system is a, bit-oriented VHF air-ground data link which will provide the functionality, capacity, data integrity, and system efficiencies that the aviation industry requires for future Air Traffic Services (ATS) and the current and future Airline Operational Communications (AOC) data communications. The AVPAC protocols are based on the ATN architecture and address the OSI lower layers protocols specific to the VHF sub network. AVPAC is one of the air-ground sub networks which may be used to provide communications across the ATN between aircraft-based application processes and their ground-based peer process.
Avionics Standard Communication Bus
The avionics standard communication bus is the physical connection between common avionics system elements carrying the digital data.
Azimuth Change Pulses
See Azimuth Count Pulses
Azimuth Count Pulses
The output pulses of the incremental azimuth measuring device fitted to the radar antenna turning platform (turning gear). The encoding device may give its output in serial or parallel form, but typically provides 4096 pulses (12 bit encoding), 16 384 pulses (14 bit encoding) or 65 536 pulses (16 bit encoding) in serial form per 360° of azimuth rotation.