Air carrier X had TCASII RA with intrail cpr Y.

Attributes
ACN	200207
Time
Date	199201
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : ord
State Reference	IL
Altitude	msl bound lower : 10000 msl bound upper : 13000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : ord
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	cruise other
Route In Use	enroute : on vectors enroute airway : zau
Flight Plan	IFR
Aircraft 2
Operator	general aviation : corporate
Make Model Name	Medium Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	cruise other
Route In Use	enroute : direct
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : departure
Qualification	controller : radar
ASRS Report	200207
Person 2
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Events
Anomaly	conflict : airborne less severe other anomaly other
Independent Detector	other flight crewa
Resolutory Action	none taken : anomaly accepted
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 30000 vertical : 0
Supplementary
Air Traffic Incident	other

Narrative:

While working west departure at O'hare, I was vectoring several aircraft in trail to provide the 7 mi required spacing over iow fix. I assigned air carrier X 13000 and instructed him to increase speed to 300 KTS or greater out 10000. I had cpr Y at 9000 approximately 3-4 mi behind air carrier X. I climbed cpr Y to 13000 and assigned 250 KTS. I waited for the spacing between the two aircraft to increase to 7 mi, and then told cpr Y to resume normal speed. I switched air carrier X to the center. Approximately 2 min later, air carrier X came back to me, and asked if I had had traffic behind him on climb out. I stated yes, and described the scenario. The pilot informed me that he had a TCASII RA instructing him to descend. Although TCASII is a needed addition to the air traffic system, had the pilot followed the RA, he would have descended below 10000, reduced his speed, and been preoccupied with possible traffic. This would have had a 'ripple' effect on at least 7 other aircraft routed over iow. At the present rate of installation, most air carriers will have TCASII by 1993. The increase in TCASII incident will have an effect on the safety and efficiency of the ATC system, unless we are able to refine how the equipment is integrated within the system.

Original NASA ASRS Text

Title: ACR X HAD TCASII RA WITH INTRAIL CPR Y.

Narrative: WHILE WORKING W DEP AT O'HARE, I WAS VECTORING SEVERAL ACFT IN TRAIL TO PROVIDE THE 7 MI REQUIRED SPACING OVER IOW FIX. I ASSIGNED ACR X 13000 AND INSTRUCTED HIM TO INCREASE SPD TO 300 KTS OR GREATER OUT 10000. I HAD CPR Y AT 9000 APPROX 3-4 MI BEHIND ACR X. I CLBED CPR Y TO 13000 AND ASSIGNED 250 KTS. I WAITED FOR THE SPACING BTWN THE TWO ACFT TO INCREASE TO 7 MI, AND THEN TOLD CPR Y TO RESUME NORMAL SPD. I SWITCHED ACR X TO THE CTR. APPROX 2 MIN LATER, ACR X CAME BACK TO ME, AND ASKED IF I HAD HAD TFC BEHIND HIM ON CLBOUT. I STATED YES, AND DESCRIBED THE SCENARIO. THE PLT INFORMED ME THAT HE HAD A TCASII RA INSTRUCTING HIM TO DSND. ALTHOUGH TCASII IS A NEEDED ADDITION TO THE AIR TFC SYS, HAD THE PLT FOLLOWED THE RA, HE WOULD HAVE DSNDED BELOW 10000, REDUCED HIS SPD, AND BEEN PREOCCUPIED WITH POSSIBLE TFC. THIS WOULD HAVE HAD A 'RIPPLE' EFFECT ON AT LEAST 7 OTHER ACFT ROUTED OVER IOW. AT THE PRESENT RATE OF INSTALLATION, MOST AIR CARRIERS WILL HAVE TCASII BY 1993. THE INCREASE IN TCASII INCIDENT WILL HAVE AN EFFECT ON THE SAFETY AND EFFICIENCY OF THE ATC SYS, UNLESS WE ARE ABLE TO REFINE HOW THE EQUIP IS INTEGRATED WITHIN THE SYS.

Data retrieved from NASA's ASRS site as of July 2007 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.