Air carrier descended through altitude of another air carrier resulting in less than standard separa...

Attributes
ACN	120804
Time
Date	198907
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : aco
State Reference	OH
Altitude	msl bound lower : 15000 msl bound upper : 15000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zob
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	descent other
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
ASRS Report	120804
Person 2
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation non adherence : published procedure
Independent Detector	atc equipment other atc equipment : unspecified other controllera
Resolutory Action	controller : issued new clearance
Consequence	Other
Miss Distance	horizontal : 18000 vertical : 0
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Training was in progress at two sectors which were combined. The trainee was certified at the sector in which the error occurred. Traffic was moderate. There was spacing involved in the sector for aircraft inbound to pit. The two aircraft involved in the error were both pit inbnds. Aircraft #1 was coming from the high altitude sector (SFL240), aircraft #2 departed cle requesting 15,000. Aircraft #1 had been issued a clearance to cross cutta (inbound fix to pit) at 10,000'. He had also been told not to exceed 290 KTS IAS. The departure off cle was climbed to 15,000' and told not to exceed 280 KTS. Before lateral separation was obtained, aircraft #1 descended thru the altitude of aircraft #2. As the controller responsible for the airspace, I feel a few things contributed to the error: 1) the trainee was certified at the sector where the error occurred, which made me hesitate to tell him to stop aircraft #1 above aircraft #2 until it was too late. 2) three clrncs were 'blocked' or otherwise missed, which may have kept the aircraft separated. 3) aircraft #1, an air carrier medium large transport, slowed below 290 KTS, which is not normal for (company) pilots.

Original NASA ASRS Text

Title: ACR DESCENDED THROUGH ALT OF ANOTHER ACR RESULTING IN LESS THAN STANDARD SEPARATION.

Narrative: TRAINING WAS IN PROGRESS AT TWO SECTORS WHICH WERE COMBINED. THE TRAINEE WAS CERTIFIED AT THE SECTOR IN WHICH THE ERROR OCCURRED. TFC WAS MODERATE. THERE WAS SPACING INVOLVED IN THE SECTOR FOR ACFT INBND TO PIT. THE TWO ACFT INVOLVED IN THE ERROR WERE BOTH PIT INBNDS. ACFT #1 WAS COMING FROM THE HIGH ALT SECTOR (SFL240), ACFT #2 DEPARTED CLE REQUESTING 15,000. ACFT #1 HAD BEEN ISSUED A CLRNC TO CROSS CUTTA (INBND FIX TO PIT) AT 10,000'. HE HAD ALSO BEEN TOLD NOT TO EXCEED 290 KTS IAS. THE DEP OFF CLE WAS CLIMBED TO 15,000' AND TOLD NOT TO EXCEED 280 KTS. BEFORE LATERAL SEPARATION WAS OBTAINED, ACFT #1 DESCENDED THRU THE ALT OF ACFT #2. AS THE CTLR RESPONSIBLE FOR THE AIRSPACE, I FEEL A FEW THINGS CONTRIBUTED TO THE ERROR: 1) THE TRAINEE WAS CERTIFIED AT THE SECTOR WHERE THE ERROR OCCURRED, WHICH MADE ME HESITATE TO TELL HIM TO STOP ACFT #1 ABOVE ACFT #2 UNTIL IT WAS TOO LATE. 2) THREE CLRNCS WERE 'BLOCKED' OR OTHERWISE MISSED, WHICH MAY HAVE KEPT THE ACFT SEPARATED. 3) ACFT #1, AN ACR MLG, SLOWED BELOW 290 KTS, WHICH IS NOT NORMAL FOR (COMPANY) PLTS.

Data retrieved from NASA's ASRS site as of August 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.

Air carrier descended through altitude of another air carrier resulting in less than standard separation.