A B757 TCAS issued 'climb; climb' commands accompanied by a target indicating 00 on the nose. ATC ad...

Narrative:

TCAS RA 'climb climb' command immediately after takeoff. Target displayed '00' on the tip of the nose. We took evasive action. Command 'climb climb' and target of '00' stayed with us until about 8;000 feet. Advised ATC we had an RA and inquired about traffic. ATC confirmed no traffic existed.ACARS'ed maintenance control. Although the RA had discontinued; they had us cycle the transponders. The incident happened using the right transponder. We cycled them and selected left transponder. By the time we reached cruise; the system was operating fine and maintenance and dispatch cleared us to continue. No TCAS abnormalities occurred for the remainder of flight.maintenance reported some history of this problem and that cycling the transponders resolved the issue. It seems to be a situation in which the aircraft is picking up its own shadow and reading it as a conflict. In the past; maintenance cleared this as an intermediate problem that cleared itself. It appears that it is more serious. I wrote it up under frm codes 34.45.05 and 34.45.07. After landing; I called in to maintenance to make certain this item was given proper attention. They agreed that the system needed in-depth testing and informed me they intended to remove the unit and give it a full bench test.

Original NASA ASRS Text

Title: A B757 TCAS issued 'CLIMB; CLIMB' commands accompanied by a target indicating 00 on the nose. ATC advised no traffic in the area and the alert ceased at about 8;000 feet. Maintenance reported that aircraft's previous Null Bus Fault record.

Narrative: TCAS RA 'CLIMB CLIMB' Command immediately after takeoff. Target displayed '00' on the tip of the nose. We took evasive action. Command 'CLIMB CLIMB' and target of '00' stayed with us until about 8;000 feet. Advised ATC we had an RA and inquired about traffic. ATC confirmed no traffic existed.ACARS'ed Maintenance Control. Although the RA had discontinued; they had us cycle the transponders. The incident happened using the R transponder. We cycled them and selected L transponder. By the time we reached cruise; the system was operating fine and Maintenance and Dispatch cleared us to continue. No TCAS abnormalities occurred for the remainder of flight.Maintenance reported some history of this problem and that cycling the transponders resolved the issue. It seems to be a situation in which the aircraft is picking up its own shadow and reading it as a conflict. In the past; Maintenance cleared this as an intermediate problem that cleared itself. It appears that it is more serious. I wrote it up under FRM codes 34.45.05 and 34.45.07. After landing; I called in to Maintenance to make certain this item was given proper attention. They agreed that the system needed in-depth testing and informed me they intended to remove the unit and give it a full bench test.

Data retrieved from NASA's ASRS site 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.

Attributes
ACN	1190560
Time
Date	201407
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	B757-200
Operating Under FAR Part	Part 121
Flight Phase	Climb Initial Climb
Flight Plan	IFR
Component
Aircraft Component	Traffic Collision Avoidance System (TCAS)
Person 1
Function	Captain Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Procedural Maintenance

A B757 TCAS issued 'climb; climb' commands accompanied by a target indicating 00 on the nose. ATC advised no traffic in the area and the alert ceased at about 8;000 feet. Maintenance reported that aircraft's previous null bus fault record.