Provider Aborts Count
The provider aborts count is a part of the general performance measures gathered as a part of the performance statistics. It provides two different ways of measuring the provider abort rate: i) a count of the number of Provider Aborts experienced as a percentage of the CPDLC sessions conducted (a CPDLC session starts when the CPDLC start request is accepted and ends when the CPDLC end request is accepted or the session is aborted for some reason) and ii) a measure of the number of provider aborts that are expereinced per 100 hours of CPDLC usage. The former measure is what the community has used for some time (coming from the time when only MUAC was using CPDLC), but the latter method is preferred for measuring performance against targets as the likelihood of a CPDLC session suffering a PA is related to the time duration of the CPDLC session (i.e. the longer a CPDLC session the more likely it is to suffer a PA), and the length of CPDLC sessions can vary quite considerably between different ANSPs. So for the measurement of performance against common European targets the number of PAs suffered per 100 hours CPDLC usage is preferred. The CPDLC usage is calculated by substratcing the CPDLC session start time from the CPDLC session end time for each CPDLC session.
FANs does not have the concept of a Provider Abort but the 'FANS1/A to ATN Interop' document (ED154) defines a set of FANS conditions that are to be considered as a Provider Abort by an ATN ground system. These conditions are as follows:
- The transmission of an uplink error message UM159 with errorInformation equal to 'invalid data', 'insufficientdata', or 'commanded termination'
- The reception of a downlink error message DM62 with errorInformation equal to 'invalid data' or 'insufficientdata'
However at the moment the ground systems do not provide PA reports for FANS aircraft.