ZKC controller experienced loss of separation event between an air carrier and military aircraft whe...

Narrative:

Air carrier X was established direct vla on the VLA6 STAR when he checked on my frequency level at FL240. Military Y; a flight of 3 military aircraft; was already on my frequency established in a block altitude FL220 to 230. The military aircraft were approximately 3 miles east of the air carrier X. The aircraft were going to eventually cross out and diverge and I was then going to get lower for air carrier X. I issued the traffic to both aircraft and they both reported traffic in sight. Air carrier X then needed to be turned to avoid traffic in the sector above my sector at FL240. So after getting control from the sector above me I issued direct petti intersection; which turned air carrier X to a more southwesterly heading. After the conflict was resolved in the high sector I then realized that military Y and air carrier X were not going to diverge quickly enough to get air carrier X down to cross petti at 110; so I issued to air carrier X 'for your descent fly heading one eight zero.' air carrier X replied 'one eight zero'. I then scanned the sector to take care of some other tasks that needed to be completed. Approximately 30 seconds later air carrier X questioned me about the descent to FL180!? I told him to maintain fl 240. He then said; 'oh yeah heading one eight zero.' by this time he had already started his descent and lateral separation was possibly compromised. I was then alerted that the 'snitch' went off and was relieved from position. Recommendation; I think it is completely unacceptable that we as controllers are held accountable for everything that comes out of our mouth; and pilots can fly around like cowboys saying what ever they want. This was clearly a pilot problem; first not listening; and second with the read back being completely unclear. When a heading is issued pilots should have to use a term such as 'turn' or 'degrees.' when an altitude is issued in class a; pilots should be required to preface it with 'flight level.' when not in class a they should have to follow the altitude read back with something like 'feet'. We are expected to hear read backs; well the read backs should be clear.

Original NASA ASRS Text

Title: ZKC Controller experienced loss of separation event between an Air Carrier and Military aircraft when he/she issued a heading to avoid traffic. The Air Carrier; believing assignment was an altitude instruction; began a descent.

Narrative: Air Carrier X was established direct VLA on the VLA6 STAR when he checked on my frequency level at FL240. Military Y; a flight of 3 military aircraft; was already on my frequency established in a block altitude FL220 to 230. The military aircraft were approximately 3 miles East of the Air Carrier X. The aircraft were going to eventually cross out and diverge and I was then going to get lower for Air Carrier X. I issued the traffic to both aircraft and they both reported traffic in sight. Air Carrier X then needed to be turned to avoid traffic in the sector above my sector at FL240. So after getting control from the sector above me I issued direct PETTI intersection; which turned Air Carrier X to a more Southwesterly heading. After the conflict was resolved in the high sector I then realized that Military Y and Air Carrier X were not going to diverge quickly enough to get Air Carrier X down to cross PETTI at 110; so I issued to Air Carrier X 'for your descent fly heading one eight zero.' Air Carrier X replied 'one eight zero'. I then scanned the sector to take care of some other tasks that needed to be completed. Approximately 30 seconds later Air Carrier X questioned me about the descent to FL180!? I told him to maintain FL 240. He then said; 'Oh yeah heading one eight zero.' By this time he had already started his descent and lateral separation was possibly compromised. I was then alerted that the 'snitch' went off and was relieved from position. Recommendation; I think it is completely unacceptable that we as controllers are held accountable for everything that comes out of our mouth; and pilots can fly around like cowboys saying what ever they want. This was clearly a pilot problem; first not listening; and second with the read back being completely unclear. When a heading is issued pilots should have to use a term such as 'turn' or 'degrees.' When an altitude is issued in Class A; pilots should be required to preface it with 'flight level.' When not in Class A they should have to follow the altitude read back with something like 'feet'. We are expected to hear read backs; well the read backs should be clear.

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.

Attributes
ACN	864624
Time
Date	200912
Local Time Of Day	0001-0600
Place
Locale Reference	ZKC.ARTCC
State Reference	KS
Aircraft 1
Make Model Name	EMB ERJ 145 ER&LR
Operating Under FAR Part	Part 121
Flight Phase	Descent
Route In Use	STAR VLA6
Flight Plan	IFR
Aircraft 2
Make Model Name	Military
Operating Under FAR Part	Part 91
Flight Phase	Cruise
Route In Use	None
Flight Plan	IFR
Person 1
Function	Enroute
Qualification	Air Traffic Control Fully Certified
Person 2
Function	First Officer
Events
Anomaly	Conflict Airborne Conflict Deviation - Procedural Published Material / Policy

ZKC controller experienced loss of separation event between an air carrier and military aircraft when he/she issued a heading to avoid traffic. The air carrier; believing assignment was an altitude instruction; began a descent.