Narrative:

Prior to departing sna we loaded the FMC using normal procedures. We selected the ATC page; loaded the appropriate information and signed-in. We received a ready prompt but did not get a clearance. Shortly before push we still had not received a cpdlc clearance so we requested a clearance via pre departure clearance. We got a pre departure clearance reply message stating to use cpdlc and simultaneously a clearance was uploaded to the FMC ATC page. The clearance showed our departure and transition as filed as well as the altitude restrictions; expected altitude; squawk; and departure frequencies as we expected to see. The ATC page did not state it was a revised clearance/route. All obvious indications were our clearance was unchanged from the filed route. A load prompt and accept prompt were shown. We accepted the clearance but because we had already loaded the flight plan we did not reload the flight plan sent via cpdlc. We departed as normal. Once airborne passing 10;000 feet we received an ACARS flight progress print out that showed our originally filed course. After passing trm; ATC stated they showed us off course. They gave us a revised route clearance and asked us to call ATC upon landing. They did not advise us of any pilot deviation or read us a brasher statement/warning. We immediately suspected that the cpdlc clearance had changed our originally filed route. Since there was no print out of our clearance to reference and since the cpdlc did not display the full route clearance we had difficulty tracking down whether or not there was actually a change to our originally filed route. We were able to find a load prompt on page 3 of the ATC clearance page. When we selected load; a new route was loaded to the FMC which was different from our originally filed route. We discovered our route had in fact been changed via cpdlc. We erased the change since we already had a new route assigned by ATC airborne and continued uneventfully to our destination.we contacted dispatch and asked if they had received a revised route. Dispatch stated that they have a re-route tool that prompts them whenever the route has been changed from what was filed. Dispatch stated that they did not get the prompt and it wasn't until we asked about the change that they became aware that our route had been changed. The dispatcher said since they did not get the prompt; they could not tell when the change hit their system.upon landing we contacted the ATC/FAA representative as requested and they explained that they are having a great many problems with cpdlc clearances within the la basin. They stated that all airlines are experiencing difficulties and that they were seeing at least 2 to 3 problems per week at a minimum. They stated that most of the problems involved route changes that occurred while using cpdlc to obtain departure clearances.we were then contacted by a representative of the FAA that is working the cpdlc transition. They reiterated the numerous problems that they were experiencing with cpdlc and the need to make improvements to the system. In our discussion with her several cpdlc shortfalls/recommendations were discussed.1. The cpdlc clearance should be able to be printed in full so that it can be compared against what's in the FMC and the flight plan. 2. Cpdlc should display the full route clearance if any revision has occurred. Just as clearance delivery would read the full route clearance if a route change has occurred or pre departure clearance would clearly show the revised segment; cpdlc should do the same.3. Cpdlc should clearly state there is a revised route. For decades ATC has used the term 'revised route' anytime a filed flight plan is changed. Cpdlc should advise that a route has been 'revised' if any route change has been made. Terminology such as 'revised route' or 'load revised route' might be helpful.

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Original NASA ASRS Text

Title: B737NG flight crew experienced a clearance anomaly from the domestic CPDLC system. Clearance was revised and loaded into the FMC without any method of notification to the crew. The CPDLC system is not capable of printouts of the clearance.

Narrative: Prior to departing SNA we loaded the FMC using normal procedures. We selected the ATC page; loaded the appropriate information and signed-in. We received a ready prompt but did not get a clearance. Shortly before push we still had not received a CPDLC clearance so we requested a clearance via PDC. We got a PDC reply message stating to use CPDLC and simultaneously a clearance was uploaded to the FMC ATC page. The clearance showed our departure and transition as filed as well as the altitude restrictions; expected altitude; squawk; and departure frequencies as we expected to see. The ATC page did not state it was a revised clearance/route. All obvious indications were our clearance was unchanged from the filed route. A load prompt and accept prompt were shown. We accepted the clearance but because we had already loaded the flight plan we did not reload the flight plan sent via CPDLC. We departed as normal. Once airborne passing 10;000 feet we received an ACARS flight progress print out that showed our originally filed course. After passing TRM; ATC stated they showed us off course. They gave us a revised route clearance and asked us to call ATC upon landing. They did not advise us of any pilot deviation or read us a Brasher statement/warning. We immediately suspected that the CPDLC clearance had changed our originally filed route. Since there was no print out of our clearance to reference and since the CPDLC did not display the full route clearance we had difficulty tracking down whether or not there was actually a change to our originally filed route. We were able to find a load prompt on page 3 of the ATC clearance page. When we selected load; a new route was loaded to the FMC which was different from our originally filed route. We discovered our route had in fact been changed via CPDLC. We erased the change since we already had a new route assigned by ATC airborne and continued uneventfully to our destination.We contacted dispatch and asked if they had received a revised route. Dispatch stated that they have a re-route tool that prompts them whenever the route has been changed from what was filed. Dispatch stated that they did not get the prompt and it wasn't until we asked about the change that they became aware that our route had been changed. The dispatcher said since they did not get the prompt; they could not tell when the change hit their system.Upon landing we contacted the ATC/FAA representative as requested and they explained that they are having a great many problems with CPDLC clearances within the LA basin. They stated that all airlines are experiencing difficulties and that they were seeing at least 2 to 3 problems per week at a minimum. They stated that most of the problems involved route changes that occurred while using CPDLC to obtain departure clearances.We were then contacted by a representative of the FAA that is working the CPDLC transition. They reiterated the numerous problems that they were experiencing with CPDLC and the need to make improvements to the system. In our discussion with her several CPDLC shortfalls/recommendations were discussed.1. The CPDLC clearance should be able to be printed in full so that it can be compared against what's in the FMC and the flight plan. 2. CPDLC should display the full route clearance if any revision has occurred. Just as clearance delivery would read the full route clearance if a route change has occurred or PDC would clearly show the revised segment; CPDLC should do the same.3. CPDLC should clearly state there is a revised route. For decades ATC has used the term 'revised route' anytime a filed flight plan is changed. CPDLC should advise that a route has been 'revised' if any route change has been made. Terminology such as 'Revised Route' or 'Load Revised Route' might be helpful.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.