Air carrier medium large transport altitude deviation excursion from clearance altitude in response ...

Attributes
ACN	171318
Time
Date	199102
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : bwi
State Reference	MD
Altitude	msl bound lower : 4000 msl bound upper : 4500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : bwi
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	cruise other
Route In Use	approach : straight in
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	cruise other
Flight Plan	VFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 150 flight time total : 9000 flight time type : 4000
ASRS Report	171318
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : flight engineer pilot : atp
Experience	flight time last 90 days : 150 flight time total : 6500 flight time type : 400
ASRS Report	171121
Events
Anomaly	altitude deviation : excursion from assigned altitude conflict : airborne less severe
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : returned to intended course or assigned course
Consequence	Other
Miss Distance	horizontal : 3000 vertical : 900
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	other

Narrative:

TCAS showed the intruding traffic to be between 400' and 600' below our assigned altitude and slightly right (1/2 mi at closest point of approach) on an almost exactly opp track. A traffic advisory was generated by ACARS, followed by a RA which was acted upon. TCAS commanded a climb which was executed by the crew. The intruder traffic was neither under control of nor talking to approach control at the time. Supplemental information from acn 171121: bwi called traffic but could not confirm its altitude and it was not in radio contact. Bwi approach was told of actions and clearance received. Returned to level flight at assigned altitude when all clear via TCAS. Traffic was not sighted.

Original NASA ASRS Text

Title: ACR MLG ALT DEVIATION EXCURSION FROM CLRNC ALT IN RESPONSE TO TCAS II RA.

Narrative: TCAS SHOWED THE INTRUDING TFC TO BE BTWN 400' AND 600' BELOW OUR ASSIGNED ALT AND SLIGHTLY RIGHT (1/2 MI AT CLOSEST POINT OF APCH) ON AN ALMOST EXACTLY OPP TRACK. A TFC ADVISORY WAS GENERATED BY ACARS, FOLLOWED BY A RA WHICH WAS ACTED UPON. TCAS COMMANDED A CLB WHICH WAS EXECUTED BY THE CREW. THE INTRUDER TFC WAS NEITHER UNDER CTL OF NOR TALKING TO APCH CTL AT THE TIME. SUPPLEMENTAL INFO FROM ACN 171121: BWI CALLED TFC BUT COULD NOT CONFIRM ITS ALT AND IT WAS NOT IN RADIO CONTACT. BWI APCH WAS TOLD OF ACTIONS AND CLRNC RECEIVED. RETURNED TO LEVEL FLT AT ASSIGNED ALT WHEN ALL CLR VIA TCAS. TFC WAS NOT SIGHTED.

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.

Air carrier medium large transport altitude deviation excursion from clearance altitude in response to TCAS ii RA.