Packet Data Channel PD-channels are used for signalling and carry ground-to-air data messages. The system has been designed to support a number of PD-channels in anticipation of continuing traffic growth.
Packet Layer Protocol To establish and maintain a connection between peer level entities at the network layer, and to transfer data packets between them.
Packet Mode Channel In the AMSS a Time-Division-Multiplexed (TDM) channel used for ground-to-air signalling, control and data communications. There are two types of P-Channel: PSMC-Channel and PD-Channel. Both types of channel, PSMC and PD, may be combined on a single physical P-channel.
See Packet System Management and Control Channel, Packet Data Channel.
Packet Switched Data Network 1- The Packet Switched Data Network provides the three-level X-25 service. With this type of network, teletext messages and facsimile images are transmitted as a sequence of packets.
2- An X.25 PSDN is a communications network that provides a network access service in compliance with ITU Recommendation X.25. X.25 is a strictly user to network interface and addresses only the physical, data link, and network layers of the ISO seven layer models. The network layer of X.25 specifies three switching services offered in a switched data network; permanent virtual circuit, virtual call, and datagram.
Packet System Management and Control Channel
A PSMC-Channel is continuously broadcast by each GES to inform users of system status and configuration. It also carries the time and frequency information needed by AESs wishing to log on to the system. Because of its importance for system integrity, the PSMC-channel has the most robust transmission link design of all the channels.
Paper Sift
The sift of application forms and attached application material in order to pre-select candidates
according to previously defined criteria.
Parameter Estimation
See Systematic Errors.
Parameters
Numerical values that describe relationsqhips in a systems and are considered constant, at least during the computation span of one model run. Parameters are shown by a circular converter in STELLA and by other symbols in other software.
Parking Position
The area or identifier of the gate or stand at which an aircraft is parked or is planned to be parked.
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Part Task Practice A method to practice, in restricted or in real time, part of the skills which are necessary for the operational task in a realistic environment (Part Task Trainer or simulator). Part Task Trainer A training machine for the student to practice some operational functions independently of other functions which are not represented there, although they are necessarily associated to the first ones in the operational task. Passive Mode of Real-Time Civil/Military Co-ordina Is the system-supported communication mode of information in real-time between civil and military units without any action by the controller(s). Path Following Error That portion of the guidance signal error which could cause aircraft displacement from the desired course or glide path. These perturbations fall within the loop guidance bandwidth of an aircraft. The path following error is composed of the path following noise and the mean course error, in the case of azimuth functions, or the mean glide path error, in the case of elevation functions. The PFE is measured by filtering the output flight navigation error record with a second order low pass filter with a corner frequency of 0.5 radians per second lateral guidance and 1.5 radians per second for vertical guidance and a slope of 12 dB/octave for both cases. Payback Period The elapsed time from the commencement of expenditure on a project to the point where the value of benefits have exactly covered accumulated costs. Percentage Delayed Flights Total minutes of departure Delay/Number of delayed flights. Each of these indicators should be calculated for departure delays arising from any cause and for departure delays caused by ATM. This will allow ATM related delay to be put into perspective. Percentile A value above and below which a specified percentage of cases fall. Percentile Rank The percentage of scores in a specified distribution that fall at or below the point at which a given score lies (CDSEPT, 1996). Performance The effectiveness and value or work behaviour and its outcomes (SIOP, 1987). Performance Management Performance management enables the behaviour of resources and the effectiveness of communication activities to be evaluated. Performance management includes functions to gather statistical information, maintain and examine logs of system state histories, determine system performance under natural and artificial conditions, and alter system modes of operation for the purpose of conducting performance management activities. Permanent Air Traffic Service Route Is a permanently designated ATS route which is not subject to daily management at Level 2 by AMCs.
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