DC9-30 cargo aircraft and unknown aircraft had less than legal spacing in ZID class east.

Attributes
ACN	521798
Time
Date	200108
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	navaid : ape.vortac
State Reference	OH
Environment
Flight Conditions	Marginal
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zid.artcc artcc : zob.artcc
Operator	common carrier : air carrier
Make Model Name	DC-9 30
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zid.artcc
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	cruise : level
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : multi engine pilot : atp
Experience	flight time last 90 days : 60 flight time total : 22000 flight time type : 7000
ASRS Report	521798
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : multi engine
Experience	flight time last 90 days : 80 flight time total : 6500 flight time type : 3000
ASRS Report	521797
Events
Anomaly	non adherence : far non adherence : published procedure other anomaly other
Independent Detector	atc equipment : conflict alert other controllera
Resolutory Action	controller : separated traffic controller : issued alert controller : issued new clearance flight crew : took evasive action none taken : detected after the fact
Supplementary
Problem Areas	ATC Human Performance FAA
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

During descent into ZZZ, flight XXX from boston was not given the normal crossing restr ie: cross limps at 11000 ft as usual. The flight was on an assigned heading from ATC. At approximately 14000 ft ATC asked what are you doing, to which we replied, flying present heading as assigned. ATC instructed us to turn right to heading of 270 degrees hard turn. I immediately executed the hard right turn to heading of 270 degrees, assuming there must be a traffic conflict. At no time prior to the turn or after were we issued a TA by ATC. We did not see the traffic in question. I asked ATC if they would like us to give them a phone call on the ground. They advised no, that their alarm sounded, and would look at it later. Our DC9's do not have TCASII installed and I believe that although the system in place worked, that it probably would not have occurred had TCASII been installed.

Original NASA ASRS Text

Title: DC9-30 CARGO ACFT AND UNKNOWN ACFT HAD LESS THAN LEGAL SPACING IN ZID CLASS E.

Narrative: DURING DSCNT INTO ZZZ, FLT XXX FROM BOSTON WAS NOT GIVEN THE NORMAL XING RESTR IE: CROSS LIMPS AT 11000 FT AS USUAL. THE FLT WAS ON AN ASSIGNED HEADING FROM ATC. AT APPROX 14000 FT ATC ASKED WHAT ARE YOU DOING, TO WHICH WE REPLIED, FLYING PRESENT HEADING AS ASSIGNED. ATC INSTRUCTED US TO TURN R TO HEADING OF 270 DEGS HARD TURN. I IMMEDIATELY EXECUTED THE HARD R TURN TO HEADING OF 270 DEGS, ASSUMING THERE MUST BE A TFC CONFLICT. AT NO TIME PRIOR TO THE TURN OR AFTER WERE WE ISSUED A TA BY ATC. WE DID NOT SEE THE TFC IN QUESTION. I ASKED ATC IF THEY WOULD LIKE US TO GIVE THEM A PHONE CALL ON THE GND. THEY ADVISED NO, THAT THEIR ALARM SOUNDED, AND WOULD LOOK AT IT LATER. OUR DC9'S DO NOT HAVE TCASII INSTALLED AND I BELIEVE THAT ALTHOUGH THE SYS IN PLACE WORKED, THAT IT PROBABLY WOULD NOT HAVE OCCURRED HAD TCASII BEEN INSTALLED.

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.