CPDLC and "abeam" waypoints
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Join Date: Feb 2007
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CPDLC and "abeam" waypoints
According to our technical department, when given a direct routing that eliminates some waypoints, we are not supposed to use "abeam" points when connected with CDPLC. Reason being that it creates waypoints that are unrecognised by the ATC system (for example abeam WOLPO becomes something like WOL01).
Now, according to Jeppesen, Data Link Operations, extracted from the GOLD Manual;
4.4.6.3.2 The flight crew should include only ATC waypoints in cleared segments of the aircraft
active flight plan. However, when an ATC clearance eliminates a waypoint, it is permissible to
retain and report the point abeam of that waypoint since this ensures retention of meteorological
data associated with the eliminated waypoint.
NOTE: If the flight crew inserts non-ATC waypoints (e.g. mid-points) into the aircraft active flight
plan and activates the change, the aircraft system may trigger an ADS-C waypoint change event
report at the non-ATC waypoint, or include information about the non-ATC waypoint in the predic-
ted route group, as well as the intermediate and fixed projected intent groups. As a result, the
ADS-C report will include information about the non-ATC waypoint, which is not expected by the
ATC ground system
So the way I'm reading this (and I think it's quite clear) is; abeam points no problem, any other user made point yes problem...
Anybody with ATC and CPDLC experience any comments on this? Or any fellow colleagues that might have the same procedure?
P.s. I'm a long haul freight dog... B747-400 and -8
Now, according to Jeppesen, Data Link Operations, extracted from the GOLD Manual;
4.4.6.3.2 The flight crew should include only ATC waypoints in cleared segments of the aircraft
active flight plan. However, when an ATC clearance eliminates a waypoint, it is permissible to
retain and report the point abeam of that waypoint since this ensures retention of meteorological
data associated with the eliminated waypoint.
NOTE: If the flight crew inserts non-ATC waypoints (e.g. mid-points) into the aircraft active flight
plan and activates the change, the aircraft system may trigger an ADS-C waypoint change event
report at the non-ATC waypoint, or include information about the non-ATC waypoint in the predic-
ted route group, as well as the intermediate and fixed projected intent groups. As a result, the
ADS-C report will include information about the non-ATC waypoint, which is not expected by the
ATC ground system
So the way I'm reading this (and I think it's quite clear) is; abeam points no problem, any other user made point yes problem...
Anybody with ATC and CPDLC experience any comments on this? Or any fellow colleagues that might have the same procedure?
P.s. I'm a long haul freight dog... B747-400 and -8
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CPDLC is just electronic delivery of clearance. If you are not capable to adheere to it, just let ATCO know about that (either via CPDLC or voice). I don't see any problem if you insert another waypoint between current position and cleared waypoint and deliver ADS-C report.
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My interpretation is that the key thing is if the ATC unit uses FMC Waypoint Reporting (FMC WPR) or not. If they do, then any kind of waypoint in the FMC will be transmitted as part of the position reporting process. If FMC WPR is not used, then you can have as many user-defined waypoints as you like.
I use LIDO charts and the FMC WPR status of an ATC unit can be easily checked in the same place that you would normally check for the CPDLC logon code.
Off the top of my head Auckland Oceanic, Gander and Shanwick use FMC WPR. The number of units that use it have reduced, as it is cumbersome since position reporting data is sent to the operator first, which in turn is then forwarded to the ATC unit.
I use LIDO charts and the FMC WPR status of an ATC unit can be easily checked in the same place that you would normally check for the CPDLC logon code.
Off the top of my head Auckland Oceanic, Gander and Shanwick use FMC WPR. The number of units that use it have reduced, as it is cumbersome since position reporting data is sent to the operator first, which in turn is then forwarded to the ATC unit.
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Never had a problem with DCT TO causing ABM WPTs in regards to ATC.
Also operate the -400 and -8. After the aircraft settles on the new DCT TRK I eliminate all unnecessary abeam waypoints. I do this as most have now become just clutter with no useful purpose. If any has a wind entered I leave that in otherwise the FMC drops the wind data and as the FMC degrades the wind data over sector time unless updated it can lead to quite erroneous ETAs, fuel data etc. You still have the option/ability to enter your own wind data into any waypoint, including abeams, should you wish to do so to ensure accuracy of the FMC derived data. Really only an issue for long sector lengths between waypoints or possible transitioning through a significant wind shift.
Regularly did this particulary when the FO and/or SO said they had been told to not eliminate superfluous waypoints by their trainers. Showed them how and why to do it and the greater accuracy subsequently obtained and generally the response was somewhat along the lines of '...you can do that? no one showed us!'
Also operate the -400 and -8. After the aircraft settles on the new DCT TRK I eliminate all unnecessary abeam waypoints. I do this as most have now become just clutter with no useful purpose. If any has a wind entered I leave that in otherwise the FMC drops the wind data and as the FMC degrades the wind data over sector time unless updated it can lead to quite erroneous ETAs, fuel data etc. You still have the option/ability to enter your own wind data into any waypoint, including abeams, should you wish to do so to ensure accuracy of the FMC derived data. Really only an issue for long sector lengths between waypoints or possible transitioning through a significant wind shift.
Regularly did this particulary when the FO and/or SO said they had been told to not eliminate superfluous waypoints by their trainers. Showed them how and why to do it and the greater accuracy subsequently obtained and generally the response was somewhat along the lines of '...you can do that? no one showed us!'
As Captain Balus alludes to above, set where you are and where you are going. As an ATC with extensive experience in a procedural Environment utilising ADSC, if I require something more, I'll ask .
P.s .Balus is no more .read TUMAK.
P.s .Balus is no more .read TUMAK.
