Large Transport
Flight Crew Air Transport Pilot (ATP)
Confusion; Situational Awareness
Deviation - Altitude Overshoot; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter CFTT / CFIT
Flight Crew Returned To Clearance
Human Factors
Enroute to MMSD; I elected to input the expected approach below discontinuity to be ready to activate the expected approach. I briefed the airway minimums leading to the enroute transition from MARUX fix on V-41. We verified the approach: VOR DME-2 Runway 16 MMSD chart. Upon arrival we were given descent clearance to 8;000 feet then 6;000 feet after MARUX; cleared the VOR DME-2 Runway 16 approach. Once I heard 'cleared for approach' I activated the approach and noted approach navigation and final for the Managed Approach.I set the next segment altitude 3;600 feet and the Approach captured and showed on profile. Upon reaching 3;600 feet; ATC yelled that we were below MVA and we were supposed to be on the Approach at 6;000 feet. We both queried the approach chart; but could not see any other altitude on the approach at our location other than 3;600 feet. We continued on the profile in VFR conditions with the airport in sight. ATC again queried us on the approach and gave a heading to intercept without any altitude clearance. We stated the airport in sight and were given the visual approach. I continued on the Managed Approach to verify crossing altitudes and ground track.Upon landing we both discussed the incident and reviewed the VOR DME-2 Runway 16 chart. First Officer found a notation in the upper left inset that stated 6;000 feet for the small segment that we had descended to 3;600 feet. We both missed this notation in the briefing and review of the approach procedure. Once cleared for the Approach the Managed Approach showed on profile and Final and Navigation had captured. There was no reason to suspect an altitude deviation while on the approach.Both pilots should verify Approach Chart and fixes along with MVA altitudes and minimum segment altitudes. Crossing restrictions and DME fixes need to both be verified and briefed. If there is a way to overlay the MVA minimum altitudes over the approach chart; that would enhance altitude awareness as well as terrain along the approach path.
Pilot reported being notified by ATC that the aircraft was below minimum vectoring altitude for the VOR DME approach being flown. Pilot missed the notation on the approach plate of the altitude requirement for the approach segment in question.