E120 flight crew observes B757 take evasive action due to TCASII alert from the B757.

Attributes
ACN	449062
Time
Date	199909
Day	Tue
Local Time Of Day	1801 To 2400
Place
Locale Reference	navaid : atl.vortac
State Reference	GA
Altitude	msl bound lower : 11500 msl bound upper : 12000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	tracon : atl.tracon
Operator	common carrier : air carrier
Make Model Name	Brasilia EMB-120 All Series
Operating Under FAR Part	Part 119
Flight Phase	climbout : intermediate altitude
Route In Use	departure other
Flight Plan	IFR
Aircraft 2
Controlling Facilities	tracon : atl.tracon
Operator	common carrier : air carrier
Make Model Name	B757-200
Operating Under FAR Part	Part 121
Flight Phase	climbout : intermediate altitude
Route In Use	departure other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 3500 flight time type : 2200
ASRS Report	449062
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : instrument pilot : commercial
Events
Anomaly	altitude deviation : excursion from assigned altitude conflict : nmac non adherence : published procedure non adherence : required legal separation
Independent Detector	aircraft equipment : tcas other flight crewa other flight crewb
Resolutory Action	none taken : detected after the fact
Miss Distance	horizontal : 475 vertical : 475
Supplementary
Problem Areas	Airspace Structure Flight Crew Human Performance ATC Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Cleared on departure heading 260 degrees up to 12000 ft. Around 8000 ft, asked aircraft X to expedite through 11000 ft. Around 11500 ft, received TCASII TA. No aircraft visually. TCASII monitor indicated a target -500 ft below less than 1 mi behind, climbing and accelerating towards aircraft symbol rapidly. A few seconds later at 12000 ft, level off. TCASII monitor showed target same altitude right on top of aircraft symbol. Heard aircraft Y report they were responding to a TA. Observed a B757 in a left descending bank turn underneath left wing of our aircraft.

Original NASA ASRS Text

Title: E120 FLC OBSERVES B757 TAKE EVASIVE ACTION DUE TO TCASII ALERT FROM THE B757.

Narrative: CLRED ON DEP HDG 260 DEGS UP TO 12000 FT. AROUND 8000 FT, ASKED ACFT X TO EXPEDITE THROUGH 11000 FT. AROUND 11500 FT, RECEIVED TCASII TA. NO ACFT VISUALLY. TCASII MONITOR INDICATED A TARGET -500 FT BELOW LESS THAN 1 MI BEHIND, CLBING AND ACCELERATING TOWARDS ACFT SYMBOL RAPIDLY. A FEW SECONDS LATER AT 12000 FT, LEVEL OFF. TCASII MONITOR SHOWED TARGET SAME ALT RIGHT ON TOP OF ACFT SYMBOL. HEARD ACFT Y RPT THEY WERE RESPONDING TO A TA. OBSERVED A B757 IN A L DSNDING BANK TURN UNDERNEATH L WING OF OUR ACFT.

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.