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Enroute controller experienced a loss of separation event with a foreign registered aircraft after the aircraft failed to comply with the descent clearance even though a correct read back was received.
| Attributes | |
| ACN | 981774 |
| Time | |
| Date | 201111 |
| Local Time Of Day | 1201-1800 |
| Place | |
| Locale Reference | ZZZ.ARTCC |
| State Reference | US |
| Environment | |
| Light | Daylight |
| Aircraft 1 | |
| Make Model Name | A320 |
| Operating Under FAR Part | Part 121 |
| Flight Plan | IFR |
| Aircraft 2 | |
| Make Model Name | Falcon 900 |
| Flight Phase | Descent |
| Flight Plan | IFR |
| Person 1 | |
| Function | Enroute |
| Qualification | Air Traffic Control Fully Certified |
| Events | |
| Anomaly | Conflict Airborne Conflict Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance |
Narrative:
A falcon 900 was given a restriction to cross the intersection at FL240 from the previous controller; but they said they were unable to make the restriction and were asking for relief. I told them to descend and maintain FL240 and expect to cross the next intersection at 13;000 ft. The pilot read back the clearance perfectly. Shortly after; I notice the aircraft descending through FL240 and I asked the pilot to verify level at FL240. The pilot said he was descending through that to cross the intersection at 13;000 ft. At that time; an A320 was level at FL230 less than five miles south of the falcon 900. Standard separation was lost; but the two aircraft were never in danger of colliding. The read back from the falcon 900 was perfect; so maybe he didn't understand what an 'expect' clearance means. Being a foreign pilot in us airspace was a possible cause for the confusion.
Original NASA ASRS Text
Title: Enroute Controller experienced a loss of separation event with a foreign registered aircraft after the aircraft failed to comply with the descent clearance even though a correct read back was received.
Narrative: A Falcon 900 was given a restriction to cross the intersection at FL240 from the previous Controller; but they said they were unable to make the restriction and were asking for relief. I told them to descend and maintain FL240 and expect to cross the next intersection at 13;000 FT. The pilot read back the clearance perfectly. Shortly after; I notice the aircraft descending through FL240 and I asked the pilot to verify level at FL240. The pilot said he was descending through that to cross the intersection at 13;000 FT. At that time; an A320 was level at FL230 less than five miles south of the Falcon 900. Standard separation was lost; but the two aircraft were never in danger of colliding. The read back from the Falcon 900 was perfect; so maybe he didn't understand what an 'expect' clearance means. Being a foreign pilot in U.S. airspace was a possible cause for the confusion.
Data retrieved from NASA's ASRS site as of April 2012 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.