A B747-400 experienced an apparently phantom TCAS RA shortly after takeoff from sfo.

Attributes
ACN	900281
Time
Date	201007
Local Time Of Day	0601-1200
Place
Locale Reference	SFO.Airport
State Reference	CA
Aircraft 1
Make Model Name	B747-400
Operating Under FAR Part	Part 121
Flight Plan	IFR
Component
Aircraft Component	TCAS Equipment
Person 1
Function	Pilot Flying Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 100 Flight Crew Total 22000 Flight Crew Type 7500
Person 2
Function	Pilot Not Flying First Officer
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 230 Flight Crew Total 18000 Flight Crew Type 2200
Events
Anomaly	Aircraft Equipment Problem Critical Deviation - Procedural Published Material / Policy

Narrative:

At 1;700 we received a climb RA from TCAS. TCAS displayed the target aircraft at our exact position and altitude. We notified sfo tower and they informed us that there was no traffic in our vicinity. The ra strengthened from a "maintain vertical speed" to an "increase climb" command. The displayed target remained co-located with our aircraft and its displayed altitude remained identical to ours through 2;400 feet. After 2;400 feet the aircraft symbol went away and the ra was terminated. The PNF first officer had experienced a similar TCAS event previously. It was on a takeoff from 28R. Only his TCAS event commanded a descent. It was also with a co-located target which was displayed at his same altitude. I believe both tcas events were false warnings. ATC had nothing on radar in either instance. Both targets were displayed at the same position and altitude as the aircraft involved. Much discussion among all the crew members raised the question of whether these events could be the result of some radio interference either accidental or purposeful in nature. It would also be interesting to know if it was the same aircraft that was involved. It should also be noted that the pitch commands provided by tcas were slightly different between the captain and first officer pfd. The difference was minimal.

Original NASA ASRS Text

Title: A B747-400 experienced an apparently phantom TCAS RA shortly after takeoff from SFO.

Narrative: At 1;700 we received a climb RA from TCAS. TCAS displayed the target aircraft at our exact position AND altitude. We notified SFO tower and they informed us that there was no traffic in our vicinity. The ra strengthened from a "maintain vertical speed" to an "increase climb" command. The displayed target remained co-located with our aircraft and its displayed altitude remained identical to ours through 2;400 feet. After 2;400 feet the aircraft symbol went away and the ra was terminated. The PNF First Officer had experienced a similar TCAS event previously. It was on a takeoff from 28R. Only his TCAS event commanded a descent. It was also with a co-located target which was displayed at his same altitude. I believe both tcas events were false warnings. ATC had nothing on radar in either instance. Both targets were displayed at the same position and altitude as the aircraft involved. Much discussion among all the crew members raised the question of whether these events could be the result of some radio interference either accidental or purposeful in nature. It would also be interesting to know if it was the same aircraft that was involved. It should also be noted that the pitch commands provided by tcas were slightly different between the Captain and First Officer PFD. The difference was minimal.

Data retrieved from NASA's ASRS site as of April 2012 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.