Date: 201502
Local time of day: 1201-1800
Location: MMGL.Airport, FO
Flight conditions: VMC
Light: Daylight
Aircraft: A320
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Final Approach
ATC / advisory: TRACON MMGL
Reporter organization: Air Carrier
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Confusion; Distraction; Workload; Situational Awareness
Second reporter function: Pilot Not Flying; First Officer
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Automation Aircraft Terrain Warning; Person Flight Crew
When detected: In-flight
Result: Flight Crew Took Evasive Action; Flight Crew FLC complied w / Automation / Advisory
Contributing factors: Environment - Non Weather Related; Procedure
Primary problem: Environment - Non Weather Related

Narrative: After GDL approach control changed our approach 3 times we finally flew the VOR to runway 10 to intercept the ILS to runway 10. This was a very confusing clearance seeing as the controller could have just cleared us to the VOR to start the ILS procedure turn. Our original clearance was vectors to the ILS 10. Also; my iPad did not have a single VOR approach in it. Only the FO's iPad had the VOR approach. We confirmed that the radials and altitudes on the approach were the same; so we continued the approach. After crossing the 12 DME fix outbound on the procedure turn we could descend to 8400 feet until crossing the 12 DME fix inbound on the ILS. During the turn inbound to intercept the ILS at approximately 8500 feet we got a Caution Terrain on the GPWS. We were both somewhat confused about the warning as we could see the top of the hill and per procedure cleared to 8400 feet on the turn inbound. I turned off the autopilot and stopped the descent rate and climbed a few hundred feet. As soon as I stopped the descent the warning went away. We could only assume that it was the descent rate with open descent selected on the mode control panel that caused the warning. In any case; that certainly was a very confusing warning as per procedure you are cleared to 8400 feet on the turn inbound to the ILS. We continued to land without incident and discussed the warning after the parking checklist was finished. We both concluded that we flew the procedure correctly and that the only issue that could have caused the GPWS warning was our descent rate closure to the hills below us.


Second narrative: The weather was clear calm winds. Descending into MMGL the controller instructed us to descend 10;000 for vectors ILS 10 MMGL. While in the descent; the controller informed us we were number 5 for the approach; and reassigned the ILS DME 1 full procedure at MMGL. We asked him if we could still get vectors for ILS 10 and he denied our request. The captain briefed up the approach and the safety warning on the 10-7 page and we both referenced the spot elevation on the arc of 7;840 feet. We were cleared to the VOR and descent to 9;000. We intercepted the outbound 269 radial and set in the next altitude (8.400 feet) for the next segment of the approach. The autopilot and autothrust were both engaged and at 12 DME we started a right turn onto the arc. We had flaps 2 and 180 kts selected and the captain pulled for open descent the aircraft started to descend as we approached 8;400 feet we received a 'CAUTION; TERRAIN; TERRAIN;' the captain immediately disconnected the autopilot and arrested our descent and started a climb leveling at 8;700 feet and the caution ceased. We continued on the approach; intercepted the ILS and landing uneventfully.


Synopsis: As an A320 approached a known 7;840 foot obstacle on the MMGL ILS 10 approach; the EGPWS alerted CAUTION; TERRAIN nearing the 8;400 foot descent constraint.