Air carrier X TCASII TA with KC135 had less than standard separation. System error.

Attributes
ACN	299175
Time
Date	199503
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : gck
State Reference	KS
Altitude	msl bound lower : 31000 msl bound upper : 31000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zkc
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	cruise other descent other
Route In Use	enroute : on vectors
Flight Plan	IFR
Aircraft 2
Operator	other
Make Model Name	Stratotanker 135
Operating Under FAR Part	other : unknown
Flight Phase	cruise other
Route In Use	enroute : direct
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 20000 flight time type : 10000
ASRS Report	299175
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation
Independent Detector	aircraft equipment other aircraft equipment : unspecified other controllera
Resolutory Action	controller : issued new clearance other
Consequence	faa : investigated
Miss Distance	horizontal : 18000 vertical : 1500
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Air carrier X wbound, ZKC (133.2) had been giving us heading changes off course for traffic. ATC then turned us left for on course to garden city. Approximately 2 mins later, ATC gives us a right turn vector for traffic and then right after that, gave us an 'immediate' descent to FL290. At the same time, we got a TA with altitude reading level with us with no RA. As we are turning and descending a military KC135 goes over the top of us at FL310, level, eastbound. The first indication of this traffic on TCASII was 12 O'clock and 3-4 mi. We asked ATC for an explanation and received none. The first sighting of the KC135 was when it passed overhead while we were descending to FL290.

Original NASA ASRS Text

Title: ACR X TCASII TA WITH KC135 HAD LTSS. SYS ERROR.

Narrative: ACR X WBOUND, ZKC (133.2) HAD BEEN GIVING US HDG CHANGES OFF COURSE FOR TFC. ATC THEN TURNED US L FOR ON COURSE TO GARDEN CITY. APPROX 2 MINS LATER, ATC GIVES US A R TURN VECTOR FOR TFC AND THEN RIGHT AFTER THAT, GAVE US AN 'IMMEDIATE' DSCNT TO FL290. AT THE SAME TIME, WE GOT A TA WITH ALT READING LEVEL WITH US WITH NO RA. AS WE ARE TURNING AND DSNDING A MIL KC135 GOES OVER THE TOP OF US AT FL310, LEVEL, EBOUND. THE FIRST INDICATION OF THIS TFC ON TCASII WAS 12 O'CLOCK AND 3-4 MI. WE ASKED ATC FOR AN EXPLANATION AND RECEIVED NONE. THE FIRST SIGHTING OF THE KC135 WAS WHEN IT PASSED OVERHEAD WHILE WE WERE DSNDING TO FL290.

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.