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Giv flight crew reported departing cruise altitude without a clearance due to confusion with cpdlc communication.
| Attributes | |
| ACN | 1613422 |
| Time | |
| Date | 201901 |
| Local Time Of Day | 0001-0600 |
| Place | |
| Locale Reference | ZOA.ARTCC |
| State Reference | CA |
| Environment | |
| Light | Daylight |
| Aircraft 1 | |
| Make Model Name | Gulfstream IV / G350 / G450 |
| Operating Under FAR Part | Part 135 |
| Flight Phase | Cruise |
| Route In Use | Oceanic |
| Flight Plan | IFR |
| Person 1 | |
| Function | Pilot Flying Captain |
| Qualification | Flight Crew Multiengine Flight Crew Air Transport Pilot (ATP) Flight Crew Flight Instructor Flight Crew Instrument |
| Experience | Flight Crew Last 90 Days 95 Flight Crew Total 15000 Flight Crew Type 6000 |
| Person 2 | |
| Function | Pilot Not Flying First Officer |
| Qualification | Flight Crew Instrument Flight Crew Multiengine Flight Crew Flight Instructor Flight Crew Air Transport Pilot (ATP) |
| Experience | Flight Crew Last 90 Days 75 Flight Crew Total 4700 Flight Crew Type 75 |
| Events | |
| Anomaly | ATC Issue All Types Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance |
Narrative:
We were flying our first trip using cpdlc (controller pilot datalink communications). Approximately 78 miles west of the dialo intersection cruising at FL410. We sent a request for FL430. ATC replied unable due to traffic. [Later] we received the message 'standby your traffic is climbing.' [a few minutes later] we received the message 'your traffic is moving.' shortly after receiving [that] message we received a message that both I and my first officer interpreted as a clearance to climb to FL430. We initiated a climb rate of approximately 300 fpm. Passing approximately 41;800 feet we received a message to descend to maintain FL410. We immediately initiated a descent and returned to FL410. [We then] received the message 'maintain FL410. Possible higher once traffic moves.' [shortly thereafter] we received the message 'climb to and maintain FL430.'both myself and my first officer are perplexed with this series of events. We both saw a message which we both interpreted as a climb clearance. We both saw a message instructing us to descend to FL410. Neither of these two messages are stored in the message log.
Original NASA ASRS Text
Title: GIV flight crew reported departing cruise altitude without a clearance due to confusion with CPDLC communication.
Narrative: We were flying our first trip using CPDLC (Controller Pilot Datalink Communications). Approximately 78 miles west of the DIALO intersection cruising at FL410. We sent a request for FL430. ATC replied unable due to traffic. [Later] we received the message 'standby your traffic is climbing.' [A few minutes later] we received the message 'your traffic is moving.' Shortly after receiving [that] message we received a message that both I and my First Officer interpreted as a clearance to climb to FL430. We initiated a climb rate of approximately 300 fpm. Passing approximately 41;800 feet we received a message to descend to maintain FL410. We immediately initiated a descent and returned to FL410. [We then] received the message 'maintain FL410. Possible higher once traffic moves.' [Shortly thereafter] we received the message 'climb to and maintain FL430.'Both myself and my First Officer are perplexed with this series of events. We both saw a message which we both interpreted as a climb clearance. We both saw a message instructing us to descend to FL410. Neither of these two messages are stored in the message log.
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.