Air traffic controller reported that he advised an md-88 crew to descend to clear opposing traffic. ...

Attributes
ACN	1499404
Time
Date	201711
Local Time Of Day	1801-2400
Place
Locale Reference	ZZZ.TRACON
State Reference	US
Aircraft 1
Make Model Name	MD-88
Flight Phase	Cruise
Flight Plan	IFR
Aircraft 2
Make Model Name	Small Aircraft Low Wing 2 Eng Retractable Gear
Flight Phase	Cruise
Flight Plan	VFR
Person 1
Function	Other / Unknown
Qualification	Air Traffic Control Fully Certified
Experience	Air Traffic Control Time Certified In Pos 1 (yrs) 8
Events
Anomaly	ATC Issue All Types Conflict Airborne Conflict Deviation - Procedural Published Material / Policy

Narrative:

Aircraft X and aircraft Y were on opposite courses and were going to be in close proximity; separated by 500 vertical feet. I called traffic; aircraft Y reported aircraft X in sight. Before targets were closer than 5 miles apart; I issued a descent to aircraft X to increase vertical separation. He said he was initiating a climb in response to an RA. I said to him 'I don't think you want to do that.' aircraft X did not climb.I could have done a better job to avoid the TCAS event. The fact that TCAS told him to climb in that event was startling to me.

Original NASA ASRS Text

Title: Air Traffic Controller reported that he advised an MD-88 crew to descend to clear opposing traffic. MD-88 crew complied despite receiving a TCAS RA to climb.

Narrative: Aircraft X and Aircraft Y were on opposite courses and were going to be in close proximity; separated by 500 vertical feet. I called traffic; Aircraft Y reported Aircraft X in sight. Before targets were closer than 5 miles apart; I issued a descent to Aircraft X to increase vertical separation. He said he was initiating a climb in response to an RA. I said to him 'I don't think you want to do that.' Aircraft X did not climb.I could have done a better job to avoid the TCAS event. The fact that TCAS told him to climb in that event was startling to me.

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.

Air traffic controller reported that he advised an md-88 crew to descend to clear opposing traffic. Md-88 crew complied despite receiving a TCAS RA to climb.