Air carrier X TCASII RA descent through occupied altitude cessna 210. See and avoid concept.

Attributes
ACN	267680
Time
Date	199404
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : bwi
State Reference	MD
Altitude	msl bound lower : 10500 msl bound upper : 10500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : bwi
Operator	common carrier : air carrier
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	cruise other
Route In Use	enroute : direct
Flight Plan	IFR
Aircraft 2
Operator	general aviation : personal
Make Model Name	Cessna 120
Operating Under FAR Part	Part 91
Flight Phase	cruise other
Route In Use	enroute : direct
Flight Plan	VFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 138 flight time total : 18600 flight time type : 904
ASRS Report	267680
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	altitude deviation : excursion from assigned altitude conflict : airborne less severe non adherence : clearance
Independent Detector	aircraft equipment other aircraft equipment : unspecified other controllera
Resolutory Action	flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 1500 vertical : 0
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	other

Narrative:

Bwi approach advised X of traffic ahead at 11000 ft. Saw traffic on TCASII. Got TCASII RA to descend. Passing through 10500 ft, saw traffic at 1 O'clock position at our altitude and passing left to right. Appeared to be cessna 210. TCASII advisory disappeared so we stopped descent at 10200 ft and then returned to 11000 ft MSL. Called bwi approach on phone after landing.

Original NASA ASRS Text

Title: ACR X TCASII RA DSCNT THROUGH OCCUPIED ALT CESSNA 210. SEE AND AVOID CONCEPT.

Narrative: BWI APCH ADVISED X OF TFC AHEAD AT 11000 FT. SAW TFC ON TCASII. GOT TCASII RA TO DSND. PASSING THROUGH 10500 FT, SAW TFC AT 1 O'CLOCK POS AT OUR ALT AND PASSING L TO R. APPEARED TO BE CESSNA 210. TCASII ADVISORY DISAPPEARED SO WE STOPPED DSCNT AT 10200 FT AND THEN RETURNED TO 11000 FT MSL. CALLED BWI APCH ON PHONE AFTER LNDG.

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.