Medium Large Transport
Flight Crew Air Transport Pilot (ATP)
Situational Awareness
Aircraft Equipment Problem Less Severe
Aircraft Equipment Problem Dissipated; Flight Crew Became Reoriented
Environment - Non Weather Related; Aircraft
Approaching Mateo (SMO) on the AVASAR 2A approach to RW 5R; 'DR' (dead reckoning) appeared in the PFD. We had discussed and briefed that this could happen based on conversations with other pilots that had recently flown to MMMX. At this point; the Terrain Display disappeared. Aircraft speed was 160 knots and on profile. We used RMI and Raw Data to verify situational awareness.   Fully configured aircraft for landing prior to MEX 253 lead-in radial. Picked up course prior to PLAZA and double checked position of aircraft. (On glideslope and course). At about 600 feet AGL; we received a 'Terrain Terrain Pull Up' warning. Immediate visual reference to surrounding terrain was available in the form of: PAPI; localizer; glideslope; visual cues and Approach Plate Orientation.  The aircraft appeared to re-orient itself shortly after the warning; as the 'DR' light extinguished; Terrain re-appeared and I chose to continue the approach. No further anomalies were noted and we landed without incident. We suspect there is something causing a navigation anomaly on certain approaches into MMMX.
[Report narrative contained no additional information]
Air carrier Captain experiences a loss of GPS signal approaching SMO during arrival to MMMX. This had been expected due to other crews having experienced the same anomaly. A terrain warning is issued and ignored on short final as the GPS returns to normal.