<< >> NASA ASRS Report 172088, March 1991

TCAS RA caused flight crew to abandon descent and climb 1000'. Returned to descent to FL190 and advised center controller.

Attributes
ACN	172088
Time
Date	199103
Day	Mon
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : eno
State Reference	DE
Altitude	msl bound lower : 19500 msl bound upper : 20500
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdc
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	climbout : intermediate altitude descent other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : commercial pilot : instrument
Experience	flight time last 90 days : 150 flight time total : 25000 flight time type : 10000
ASRS Report	172088
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : commercial pilot : instrument
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other
Independent Detector	other controllera other flight crewa
Resolutory Action	flight crew : took evasive action
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Air carrier flight en route ewr. Flight cleared to descend to FL190 by dca center. When flight was out of approximately 19500' TCAS traffic advisory was heard, followed shortly after by a climb command (RA by TCAS). Aircraft was then flown as dictated by TCAS, which required a climb of approximately 2000 FPM. At approximately 20500 ft conflict was resolved and descent to FL190 was resumed. ATC was notified, and indicated they were not aware of any conflict. They did speculate that an aircraft approximately 3000' below us may have triggered the alarm, due to his high rate of climb. I believe we have a number of (bugs) to be worked out of the TCAS system. The one concerning other aircraft climbing or descending at high rates, appears to be the culprit here.

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Original NASA ASRS Text

Title: TCAS RA CAUSED FLT CREW TO ABANDON DESCENT AND CLIMB 1000'. RETURNED TO DESCENT TO FL190 AND ADVISED CENTER CTLR.

Narrative: AIR CARRIER FLT ENRTE EWR. FLT CLRED TO DSND TO FL190 BY DCA CTR. WHEN FLT WAS OUT OF APPROX 19500' TCAS TFC ADVISORY WAS HEARD, FOLLOWED SHORTLY AFTER BY A CLB COMMAND (RA BY TCAS). ACFT WAS THEN FLOWN AS DICTATED BY TCAS, WHICH REQUIRED A CLB OF APPROX 2000 FPM. AT APPROX 20500 FT CONFLICT WAS RESOLVED AND DSNT TO FL190 WAS RESUMED. ATC WAS NOTIFIED, AND INDICATED THEY WERE NOT AWARE OF ANY CONFLICT. THEY DID SPECULATE THAT AN ACFT APPROX 3000' BELOW US MAY HAVE TRIGGERED THE ALARM, DUE TO HIS HIGH RATE OF CLB. I BELIEVE WE HAVE A NUMBER OF (BUGS) TO BE WORKED OUT OF THE TCAS SYS. THE ONE CONCERNING OTHER ACFT CLBING OR DSNDING AT HIGH RATES, APPEARS TO BE THE CULPRIT HERE.

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.