Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Flight Crew Last 90 Days 433; Flight Crew Type 5000
Distraction; Troubleshooting; Situational Awareness
Conflict Ground Conflict; Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Other / Unknown
Flight Crew Took Evasive Action
Airport; Chart Or Publication
I recently did 2 MMUN turns out of ZZZ. The standard arrival procedure is to land on Runway 12L; taxi D; C; E3 to the gate. The standard departure procedure is to push off the gate; take E1 and C to Runway 12R. Upon joining E3 while taxiing to our gate during the first turn; I commented that the spacing between E1; E2; and E3 seemed tight. It was not a problem that day as there were no other aircraft movements. On the second day; we pushed off Gate XX and were disconnected on E1 (per ATC instruction). We noticed another carrier B737 with scimitars taxiing on E3 taxiing towards Gate XY. 'His' scimitar winglet appeared to be directly over the E2 lane. His nose gear was centered on the E3 lane. This is not one of those situations where my assessment of where his winglet was was off by a few feet. We had an excellent vantage point; and maybe I was off by a few inches (at most). As a side note; as one joins E3; there is a sign painted on the pavement stating that the maximum wing span is 36 METERS. That translates into 118.11 FEET; not 118 feet and 11 inches. The Boeing 737-800 with scimitars has a wing span of 117'-10'. Our B737 has a wing span of 117'-X'. If the other carrier was exactly centered on E3; and we were exactly centered on E1; our winglets would be about 12 inches apart. That works great on paper; but not in real life. We taxi around all the time in close quarters (e.g. ZZZ1); but never have I been in an airplane where the margin of error on the ground is measured in inches! The story ends with both us and the other carrier deviating off the yellow line to give ourselves a few more inches of clearance. There is no mention of wingspan limitation or caution on our airport information page; none on the 10-9 (there is a note for aircraft on E2) and nothing in the MMUN route brief. Someone needs to go out to the ramp and actually measure the spacing of E1; E2; E3. Also; there should be notes added to our pages (at the very least) urging extreme caution while taxiing on the ramp.
B737 First Officer reported the taxi lanes are very tight at MMUN.