<< >> NASA ASRS Report 518785, July 2001

B757-200 flight crew responded to a TCASII RA during initial climb on a SID departure over one of the lax VFR corridors. No other traffic observed on the aircraft TCASII screen, and no conflicting traffic was observed by the tower controller.

Attributes
ACN	518785
Time
Date	200107
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : lax.airport
State Reference	CA
Altitude	msl single value : 3300
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : sct.tracon
Operator	common carrier : air carrier
Make Model Name	B757-200
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	climbout : initial
Route In Use	departure sid : loop
Flight Plan	IFR
Aircraft 2
Controlling Facilities	tracon : sct.tracon
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : multi engine pilot : instrument pilot : flight engineer pilot : commercial pilot : atp
Experience	flight time last 90 days : 150 flight time total : 12900 flight time type : 600
ASRS Report	518785
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	conflict : nmac other anomaly other
Independent Detector	aircraft equipment : tcas other flight crewa
Resolutory Action	flight crew : took precautionary avoidance action
Consequence	faa : reviewed incident with flight crew
Miss Distance	vertical : 200
Supplementary
Problem Areas	Aircraft
Primary Problem	Aircraft

Narrative:

After takeoff from runway 24L at lax, we leveled at 3000 ft in compliance with the loop departure. When given our climb clearance, we started up and almost immediately received a TCASII RA directing us to 'monitor vertical speed' and 'descend.' the TCASII presentation showed an aircraft directly above us at 200 ft level. I clicked off the autoplt and manually descended the aircraft back to 3000 ft from 3300 ft. The RA stopped almost immediately upon descent and the target disappeared from the screen. The tower did not see any aircraft nor did we. We also had no targets on the TCASII screen until the RA came on. Previous experience with VFR aircraft transiting the VFR corridor without contacting anyone led me to believe that the RA was valid, and hazy sky conditions prevented visual sighting by us or tower/approach.

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Original NASA ASRS Text

Title: B757-200 FLC RESPONDED TO A TCASII RA DURING INITIAL CLB ON A SID DEP OVER ONE OF THE LAX VFR CORRIDORS. NO OTHER TFC OBSERVED ON THE ACFT TCASII SCREEN, AND NO CONFLICTING TFC WAS OBSERVED BY THE TWR CTLR.

Narrative: AFTER TKOF FROM RWY 24L AT LAX, WE LEVELED AT 3000 FT IN COMPLIANCE WITH THE LOOP DEP. WHEN GIVEN OUR CLB CLRNC, WE STARTED UP AND ALMOST IMMEDIATELY RECEIVED A TCASII RA DIRECTING US TO 'MONITOR VERT SPD' AND 'DSND.' THE TCASII PRESENTATION SHOWED AN ACFT DIRECTLY ABOVE US AT 200 FT LEVEL. I CLICKED OFF THE AUTOPLT AND MANUALLY DSNDED THE ACFT BACK TO 3000 FT FROM 3300 FT. THE RA STOPPED ALMOST IMMEDIATELY UPON DSCNT AND THE TARGET DISAPPEARED FROM THE SCREEN. THE TWR DID NOT SEE ANY ACFT NOR DID WE. WE ALSO HAD NO TARGETS ON THE TCASII SCREEN UNTIL THE RA CAME ON. PREVIOUS EXPERIENCE WITH VFR ACFT TRANSITING THE VFR CORRIDOR WITHOUT CONTACTING ANYONE LED ME TO BELIEVE THAT THE RA WAS VALID, AND HAZY SKY CONDITIONS PREVENTED VISUAL SIGHTING BY US OR TWR/APCH.

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.