<< >> NASA ASRS Report 245626, July 1993

Cpr Y descent through occupied altitude had less than standard separation from air carrier X TCASII RA climb. Evasive action taken. System error.

Attributes
ACN	245626
Time
Date	199307
Day	Fri
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : ard
State Reference	PA
Altitude	msl bound lower : 11000 msl bound upper : 11000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Navigation In Use	Other
Flight Phase	cruise other
Route In Use	enroute : direct enroute airway : zdc
Flight Plan	IFR
Aircraft 2
Operator	general aviation : corporate
Make Model Name	Light Transport, Low Wing, 2 Turbojet Eng
Flight Phase	descent 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 : 57 flight time total : 18500 flight time type : 8000
ASRS Report	245626
Person 2
Affiliation	company : air carrier
Function	flight crew : second officer
Qualification	pilot : atp
Experience	flight time last 90 days : 150 flight time total : 7000 flight time type : 3000
ASRS Report	245621
Events
Anomaly	altitude deviation : excursion from assigned altitude conflict : nmac non adherence : required legal separation non adherence : clearance non adherence : published procedure
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew faa : investigated
Miss Distance	horizontal : 0 vertical : 500
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error Intra Facility Coordination Failure

Narrative:

Air carrier X approaching yardley VOR at 11000 ft we received a TCASII TA (12 O'clock and 1000 ft above and descending). That was followed by a 'traffic climb' warning. We were directed via TCASII to climb at 2000 FPM. We then received a 'clear of traffic' from TCASII. When first TCASII alert was sounded we advised ATC on 132.52 and were advised of unknown traffic at 12 O'clock. After we took evasive action we informed ATC. They then confirmed cpr Y being controled by another sector had indeed descended through our assigned altitude. His last comment was 'good call.'

Related reports:

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• X descent through occupied altitude had less than standard s...

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Original NASA ASRS Text

Title: CPR Y DSCNT THROUGH OCCUPIED ALT HAD LTSS FROM ACR X TCASII RA CLB. EVASIVE ACTION TAKEN. SYS ERROR.

Narrative: ACR X APCHING YARDLEY VOR AT 11000 FT WE RECEIVED A TCASII TA (12 O'CLOCK AND 1000 FT ABOVE AND DSNDING). THAT WAS FOLLOWED BY A 'TFC CLB' WARNING. WE WERE DIRECTED VIA TCASII TO CLB AT 2000 FPM. WE THEN RECEIVED A 'CLR OF TFC' FROM TCASII. WHEN FIRST TCASII ALERT WAS SOUNDED WE ADVISED ATC ON 132.52 AND WERE ADVISED OF UNKNOWN TFC AT 12 O'CLOCK. AFTER WE TOOK EVASIVE ACTION WE INFORMED ATC. THEY THEN CONFIRMED CPR Y BEING CTLED BY ANOTHER SECTOR HAD INDEED DSNDED THROUGH OUR ASSIGNED ALT. HIS LAST COMMENT WAS 'GOOD CALL.'

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.