B737 descent through occupied altitude had less than standard separation from MU2. System error.

Attributes
ACN	311669
Time
Date	199507
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : lit
State Reference	AR
Altitude	msl bound lower : 9000 msl bound upper : 9000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air taxi
Make Model Name	MU-2F
Operating Under FAR Part	Part 135
Flight Phase	cruise other
Route In Use	enroute : direct enroute airway : lit
Flight Plan	IFR
Aircraft 2
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Person 1
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Experience	controller radar : 20
ASRS Report	311669
Person 2
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Events
Anomaly	conflict : airborne less severe non adherence : published procedure non adherence : required legal separation
Independent Detector	other controllera
Resolutory Action	none taken : detected after the fact
Consequence	faa : investigated
Miss Distance	horizontal : 4500 vertical : 300
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error Intra Facility Coordination Failure

Narrative:

Aircraft #1 at 9000 ft MSL inbound to lit. Aircraft #2 at 10000 ft MSL inbound to lit. Both aircraft were handed off from center to 2 different lit approach sectors. Both aircraft were close to lit approach boundary. Both aircraft called the same approach sector. Controller #1 told controller #2 about the aircraft headed toward his sector. Controller #2 says he did not hear controller #1. Controller #1 does not remember controller #2's response. However, controller #1 heard controller #2 talk to the aircraft in question. 1 min after that controller #2 cleared aircraft #2 through the altitude of aircraft #1, resulting in less than standard ATC separation.

Original NASA ASRS Text

Title: B737 DSCNT THROUGH OCCUPIED ALT HAD LTSS FROM MU2. SYS ERROR.

Narrative: ACFT #1 AT 9000 FT MSL INBOUND TO LIT. ACFT #2 AT 10000 FT MSL INBOUND TO LIT. BOTH ACFT WERE HANDED OFF FROM CTR TO 2 DIFFERENT LIT APCH SECTORS. BOTH ACFT WERE CLOSE TO LIT APCH BOUNDARY. BOTH ACFT CALLED THE SAME APCH SECTOR. CTLR #1 TOLD CTLR #2 ABOUT THE ACFT HEADED TOWARD HIS SECTOR. CTLR #2 SAYS HE DID NOT HEAR CTLR #1. CTLR #1 DOES NOT REMEMBER CTLR #2'S RESPONSE. HOWEVER, CTLR #1 HEARD CTLR #2 TALK TO THE ACFT IN QUESTION. 1 MIN AFTER THAT CTLR #2 CLRED ACFT #2 THROUGH THE ALT OF ACFT #1, RESULTING IN LESS THAN STANDARD ATC SEPARATION.

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.