According to #1442:
at 0210, a 3443 event, a TCAS problem (34 is navigation; 3443 is the Doppler system. The Doppler system here is used to measure relative motion of another body, in this case another aircraft, for TCAS)
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However, if as Graybeard states (#3708) no other aircraft were in transponder range, an out of spec TCAS derived parameter could not have been the reason for the message.
From the FAA booklet, 'Introduction to TCAS ii, Version 7'
Page 7:
TCAS is designed to work autonomously of the aircraft navigation equipment
and
Page 33:
The performance monitor validates many of the inputs received from other aircraft systems and validates the performance of the TCAS processor. These include the own aircraft pressure altitude input and the connection of TCAS to the aircraft suppression bus.
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This possibly suggests pressure alt as being the most likely cause, but (back to my original point) the existence of this message still questions the 'blocked pitot theory'.