<< >> NASA ASRS Report 368092, May 1997

ARTCC radar controller issued the wrong altitude to a descending medium large transport and descended the aircraft through an occupied altitude. The medium large transport did not get a TCASII alert, but the ARTCC conflict alert caught the error.

Attributes
ACN	368092
Time
Date	199705
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : psb
State Reference	PA
Altitude	msl bound lower : 14000 msl bound upper : 14700
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	descent other
Route In Use	arrival other arrival star : star enroute airway : zob
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	other : unknown
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : flight engineer pilot : cfi pilot : atp
Experience	flight time last 90 days : 60 flight time total : 10500 flight time type : 3000
ASRS Report	368092
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 180 flight time total : 10000 flight time type : 1900
ASRS Report	368670
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	faa : investigated faa : reviewed incident with flight crew
Miss Distance	horizontal : 24000 vertical : 0
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

I was off frequency communicating with flight attendant regarding a passenger issue. First officer flying received descent clearance to 14000 ft. He understood 14000 ft, read back 14000 ft, then entered 14000 ft in the altitude alerter. Descending through 14700 ft, the controller asked if we were at 15000 ft. I just returned to frequency, acknowledged the call, and stated we were descending to 14000 ft. There was previously issued traffic at our 10 O'clock position and below our altitude that we had visually. No alert was made on TCASII. ATC gave us further clearance to 10000 ft. Called ZOB, controller was issued an operational error. Supplemental information from acn 368670: we called ZOB to ask what happened. The controller's supervisor told us that the controller had given us 14000 ft in error.

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Original NASA ASRS Text

Title: ARTCC RADAR CTLR ISSUED THE WRONG ALT TO A DSNDING MLG AND DSNDED THE ACFT THROUGH AN OCCUPIED ALT. THE MLG DID NOT GET A TCASII ALERT, BUT THE ARTCC CONFLICT ALERT CAUGHT THE ERROR.

Narrative: I WAS OFF FREQ COMMUNICATING WITH FLT ATTENDANT REGARDING A PAX ISSUE. FO FLYING RECEIVED DSCNT CLRNC TO 14000 FT. HE UNDERSTOOD 14000 FT, READ BACK 14000 FT, THEN ENTERED 14000 FT IN THE ALT ALERTER. DSNDING THROUGH 14700 FT, THE CTLR ASKED IF WE WERE AT 15000 FT. I JUST RETURNED TO FREQ, ACKNOWLEDGED THE CALL, AND STATED WE WERE DSNDING TO 14000 FT. THERE WAS PREVIOUSLY ISSUED TFC AT OUR 10 O'CLOCK POS AND BELOW OUR ALT THAT WE HAD VISUALLY. NO ALERT WAS MADE ON TCASII. ATC GAVE US FURTHER CLRNC TO 10000 FT. CALLED ZOB, CTLR WAS ISSUED AN OPERROR. SUPPLEMENTAL INFO FROM ACN 368670: WE CALLED ZOB TO ASK WHAT HAPPENED. THE CTLR'S SUPVR TOLD US THAT THE CTLR HAD GIVEN US 14000 FT IN ERROR.

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.