B737 flight crew experienced a GPS outage during the VOR DME runway 05L/right approach at MMMX. An o...

Narrative:

We were cleared for the VOR-DME 5L into MMMX. WX was clear. We briefed the approach to use VNAV and vorloc. First of all; the approach depicts a turn prior to plaza to arrive on the final approach course at plaza. The FMC builds and flies an overshooting path over plaza. Additionally; we received a GPS-left invalid in the FMC scratchpad just prior to plaza. While on the path; the VNAV and FD guidance disconnected at approximately 1200-1400 ft AGL. We were visual at this time with the runway in sight and landing clearance. We continued the approach to a normal landing. We had a vertical path the entire time; but were unable to reengage the VNAV. I have been told that the GPS-left invalid and GPS-right invalid messages are a normal occurrence in MMMX. I do not see how this anomaly should have affected this flight especially since first officer was flying and the FD master was on the right side. I believe this approach is loaded wrong into the FMC causing a big overshoot since we were below the 160 kt prior to the turn.

Original NASA ASRS Text

Title: B737 flight crew experienced a GPS outage during the VOR DME RWY 05L/R approach at MMMX. An overshoot at PLAZA resulted but the crew was able to land visually.

Narrative: We were cleared for the VOR-DME 5L into MMMX. WX was clear. We briefed the approach to use VNAV and VORLOC. First of all; the approach depicts a turn prior to PLAZA to arrive on the final approach course at PLAZA. The FMC builds and flies an overshooting path over PLAZA. Additionally; we received a GPS-L invalid in the FMC scratchpad just prior to PLAZA. While on the path; the VNAV and FD guidance disconnected at approximately 1200-1400 ft AGL. We were visual at this time with the runway in sight and landing clearance. We continued the approach to a normal landing. We had a vertical path the entire time; but were unable to reengage the VNAV. I have been told that the GPS-L invalid and GPS-R invalid messages are a normal occurrence in MMMX. I do not see how this anomaly should have affected this flight especially since FO was flying and the FD master was on the right side. I believe this approach is loaded wrong into the FMC causing a big overshoot since we were below the 160 kt prior to the turn.

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	1441858
Time
Date	201704
Local Time Of Day	1201-1800
Place
Locale Reference	MMMX.Airport
State Reference	FO
Aircraft 1
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Final Approach
Flight Plan	IFR
Component
Aircraft Component	GPS & Other Satellite Navigation
Person 1
Function	Pilot Not Flying Captain
Experience	Flight Crew Last 90 Days 256 Flight Crew Total 13970 Flight Crew Type 4304
Person 2
Function	Pilot Flying First Officer
Experience	Flight Crew Type 994
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Track / Heading All Types

B737 flight crew experienced a GPS outage during the VOR DME runway 05L/right approach at MMMX. An overshoot at plaza resulted but the crew was able to land visually.