Narrative:

During our descent into mexico city we were cleared for the 'datul 4 a' arrival with the smo (mateo) IAF transition for the ILS 5R. The FMC database does not provide a transition from smo; but rather a fix named mavik; which is on the 'RNAV (GPS) or ILS runway 5R' 11-1 approach plate. Smo and mavik are within .1 NM of each other. During our descent the weather deteriorated to below landing minimums. We were cleared direct to smo to hold as published. Although we could have held at mavik; which has an identical hold to smo (see the 11-1 plate); we followed the clearance direct to smo and built the hold as published on the datul arrival. We could hear another carrier being cleared to hold also; but they were being sent to 'mavik' not 'smo'. After holding for approximately 1 hour; the weather improved to minimums and we were cleared to depart the hold via the transition for the ILS 5R. Upon reaching minimums we had to perform a missed approach. The missed approach holding fix is 'mixex' on the 'RNAV (GPS) or ILS 5R' plate 11-1. 'Mixex' is coincidental with the missed approach-holding fix 'slm (santa lucia)' on the 'ILS dem 5R' 11-2 approach plate. While flying the published missed to 'mixex' ATC cleared us direct to 'slm'. We entered direct to slm and executed the change. This deleted 'mixex' and subsequently the missed approach hold. ATC then cleared us to hold at 'slm' as published (the same hold we just deleted). This holding instruction was given to us very late. We only had seconds to enter and execute the holding pattern. The pilot monitoring did an excellent job despite his low time in the aircraft. A less experienced pilot may not have made these changes as quickly or accurately. Finally; we were cleared again direct to smo for the transition to the ILS 5R. Understanding the approach plate differences we were able to mitigate these threats and comply with ATC instructions. Due to the high workload and weather at minimums; I opted to make an auto land on the second approach.1. Air crews need to be made aware of the possible threats associated with this arrival and whether or not mavik can be substituted for smo as a transition to the ILS 5R.2. If mavik cannot be substituted for smo; then the transition can be selected and mavik deleted and replaced with smo.3. When selecting the ILS 5R from the database. The missed approach matches the 11-1 plate not the 11-2; however; the missed approach fixes appear to be collocated and have identical holding patterns.4. Mexico ATC needs to [be] made aware of these threats and that our database does not contain the smo transition. Also; our missed approach is based on the RNAV GPS or ILS 5R approach plate.

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Original NASA ASRS Text

Title: A B747 Captain described the confusion and increased work load that was caused by the differences in the IAF and missed approach holding fixes on the ILS Runway 5R and the ILS DME Runway 5R at MMMX.

Narrative: During our descent into Mexico City we were cleared for the 'DATUL 4 A' arrival with the SMO (MATEO) IAF transition for the ILS 5R. The FMC database does not provide a transition from SMO; but rather a fix named MAVIK; which is on the 'RNAV (GPS) or ILS RWY 5R' 11-1 approach plate. SMO and MAVIK are within .1 NM of each other. During our descent the weather deteriorated to below landing minimums. We were cleared direct to SMO to hold as published. Although we could have held at MAVIK; which has an identical hold to SMO (see the 11-1 plate); we followed the clearance direct to SMO and built the hold as published on the DATUL arrival. We could hear another carrier being cleared to hold also; but they were being sent to 'MAVIK' not 'SMO'. After holding for approximately 1 hour; the weather improved to minimums and we were cleared to depart the hold via the transition for the ILS 5R. Upon reaching minimums we had to perform a missed approach. The missed approach holding fix is 'MIXEX' on the 'RNAV (GPS) or ILS 5R' plate 11-1. 'MIXEX' is coincidental with the missed approach-holding fix 'SLM (SANTA LUCIA)' on the 'ILS DEM 5R' 11-2 approach plate. While flying the published missed to 'MIXEX' ATC cleared us direct to 'SLM'. We entered direct to SLM and executed the change. This deleted 'MIXEX' and subsequently the missed approach hold. ATC then cleared us to hold at 'SLM' as published (the same hold we just deleted). This holding instruction was given to us very late. We only had seconds to enter and execute the holding pattern. The pilot monitoring did an excellent job despite his low time in the aircraft. A less experienced pilot may not have made these changes as quickly or accurately. Finally; we were cleared again direct to SMO for the transition to the ILS 5R. Understanding the approach plate differences we were able to mitigate these threats and comply with ATC instructions. Due to the high workload and weather at minimums; I opted to make an auto land on the second approach.1. Air crews need to be made aware of the possible threats associated with this arrival and whether or not MAVIK can be substituted for SMO as a transition to the ILS 5R.2. If MAVIK cannot be substituted for SMO; then the transition can be selected and MAVIK deleted and replaced with SMO.3. When selecting the ILS 5R from the database. The missed approach matches the 11-1 plate not the 11-2; however; the missed approach fixes appear to be collocated and have identical holding patterns.4. MEXICO ATC needs to [be] made aware of these threats and that our database does not contain the SMO transition. Also; our missed approach is based on the RNAV GPS or ILS 5R Approach plate.

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.