Narrative:

A B747 sent a downlink via cpdlc; 'request climb to FL350; due to aircraft performance.' upon probing the requested altitude via the clearance window; atop indicated a conflict with the B737 who was northbound on L453 crossing the B747's route of flight. As per procedure; I sent an uplink to close the downlink to the aircraft stating; 'unable; due to traffic.' after performing some other tasks I went back to evaluate the B747's request for higher. After evaluating that the cross would more than likely not be a direct merge; I constructed the clearance; 'maintain FL330; at xa:52[Z] climb to and maintain FL350; climb to reach FL350 by xa:57;[Z] report level FL350' which is a standard 'at time climb by time' clearance. The aircraft sent a downlink of; 'wilco' to the clearance. While coordinating the revised altitude with the appropriate sector I noticed an arp message in the sector queue and since the aircraft was near a position that commonly gets arp reports from ads equipped aircraft I deleted it and sent a 'demand' request for another position report. Once I received the next arp I noticed that the data block indicated that the B747 was above his assigned altitude and that the arp was due to the altitude situation. The aircraft reported level at xa:48Z; four minutes before it was supposed to start its climb. The B747 climbed through the B737's altitude without the appropriate separation for aircraft on crossing tracks. Something needs to be done with cpdlc equipped aircraft to ensure that they are actually reading the clearances sent to them; not just seeing what they want to see. It was my understanding that the 'maintain flxxx' should fix this but clearly it is not a foolproof solution. Something should be done in collaboration with the pilots to reinforce the importance of fully reading cpdlc clearances before initiating a maneuver. As we move towards a non-radar environment where more aircraft will be cpdlc and ads-B equipped this has the potential to become a much bigger problem.

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Original NASA ASRS Text

Title: ZNY Controller described a loss of separation event reportedly caused by the flight crew not reading the entire CPDLC instruction.

Narrative: A B747 sent a downlink via CPDLC; 'Request Climb to FL350; due to aircraft performance.' Upon probing the requested altitude via the clearance window; ATOP indicated a conflict with the B737 who was northbound on L453 crossing the B747's route of flight. As per procedure; I sent an uplink to close the downlink to the aircraft stating; 'Unable; Due to traffic.' After performing some other tasks I went back to evaluate the B747's request for higher. After evaluating that the cross would more than likely not be a direct merge; I constructed the clearance; 'Maintain FL330; at XA:52[Z] climb to and maintain FL350; climb to reach FL350 by XA:57;[Z] Report level FL350' which is a standard 'at time climb by time' clearance. The aircraft sent a downlink of; 'WILCO' to the clearance. While coordinating the revised altitude with the appropriate sector I noticed an ARP message in the sector queue and since the aircraft was near a position that commonly gets ARP reports from ADS equipped aircraft I deleted it and sent a 'Demand' request for another position report. Once I received the next ARP I noticed that the data block indicated that the B747 was above his assigned altitude and that the ARP was due to the altitude situation. The aircraft reported level at XA:48Z; four minutes before it was supposed to start its climb. The B747 climbed through the B737's altitude without the appropriate separation for aircraft on crossing tracks. Something needs to be done with CPDLC equipped aircraft to ensure that they are actually reading the clearances sent to them; not just seeing what they want to see. It was my understanding that the 'Maintain FLXXX' SHOULD fix this but clearly it is not a foolproof solution. Something should be done in collaboration with the pilots to reinforce the importance of fully reading CPDLC clearances before initiating a maneuver. As we move towards a non-RADAR environment where more aircraft will be CPDLC and ADS-B equipped this has the potential to become a much bigger problem.

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.