A DC8 experienced 2 TCAS RA's on final to bfi. The first RA was climbing; the second descending. ATC...

Attributes
ACN	700535
Time
Date	200606
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : bfi.tower
State Reference	WA
Altitude	msl single value : 2200
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : bfi.tower
Operator	common carrier : air carrier
Make Model Name	DC-8 70
Operating Under FAR Part	Part 121
Navigation In Use	ils localizer & glide slope : 13r other
Flight Phase	descent : approach
Route In Use	approach : instrument precision
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : cfi pilot : multi engine pilot : commercial pilot : instrument
Experience	flight time last 90 days : 75 flight time total : 10000 flight time type : 5000
ASRS Report	700535
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	aircraft equipment problem : critical altitude deviation : excursion from assigned altitude
Independent Detector	aircraft equipment : tcas other flight crewa
Resolutory Action	aircraft : equipment problem dissipated
Consequence	faa : reviewed incident with flight crew other
Supplementary
Problem Areas	Maintenance Human Performance Aircraft
Primary Problem	Aircraft

Narrative:

On flight from ZZZ to bfi; we encountered a TCAS RA. The flight was at 2200 ft MSL over nolla on the ILS runway 13R. The hard RA commanded an immediate maximum ivsi climb due to traffic at our altitude. We complied with the hard RA per company procedures. The RA maximum climb command continued until 5000 ft. The traffic showed level to 100 ft low; throughout the entire RA incident. Then we got a maximum ivsi RA descent command until reaching 4200 ft. Upon reaching 4200 ft; the system showed no threat of traffic any longer. The rest of the flight was uneventful. I placed a call to the tower at bfi and talked with the controller; who worked our airplane during the RA. The controller stated there was no traffic close enough to set our TCAS off.callback conversation with reporter revealed the following information: reporter stated that maintenance was unable to find a problem with the TCAS. Maintenance sensed that the TCAS was commanding him to escape from himself. This same aircraft had a similar problem the following day at FL280.

Original NASA ASRS Text

Title: A DC8 EXPERIENCED 2 TCAS RA'S ON FINAL TO BFI. THE FIRST RA WAS CLBING; THE SECOND DSNDING. ATC RPTED NO TFC.

Narrative: ON FLT FROM ZZZ TO BFI; WE ENCOUNTERED A TCAS RA. THE FLT WAS AT 2200 FT MSL OVER NOLLA ON THE ILS RWY 13R. THE HARD RA COMMANDED AN IMMEDIATE MAX IVSI CLB DUE TO TFC AT OUR ALT. WE COMPLIED WITH THE HARD RA PER COMPANY PROCS. THE RA MAX CLB COMMAND CONTINUED UNTIL 5000 FT. THE TFC SHOWED LEVEL TO 100 FT LOW; THROUGHOUT THE ENTIRE RA INCIDENT. THEN WE GOT A MAX IVSI RA DSCNT COMMAND UNTIL REACHING 4200 FT. UPON REACHING 4200 FT; THE SYSTEM SHOWED NO THREAT OF TFC ANY LONGER. THE REST OF THE FLT WAS UNEVENTFUL. I PLACED A CALL TO THE TWR AT BFI AND TALKED WITH THE CTLR; WHO WORKED OUR AIRPLANE DURING THE RA. THE CTLR STATED THERE WAS NO TFC CLOSE ENOUGH TO SET OUR TCAS OFF.CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THAT MAINT WAS UNABLE TO FIND A PROB WITH THE TCAS. MAINT SENSED THAT THE TCAS WAS COMMANDING HIM TO ESCAPE FROM HIMSELF. THIS SAME ACFT HAD A SIMILAR PROB THE FOLLOWING DAY AT FL280.

Data retrieved from NASA's ASRS site as of January 2009 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.

A DC8 experienced 2 TCAS RA's on final to bfi. The first RA was climbing; the second descending. ATC reported no traffic.