Date: 201405
Local time of day: 1201-1800
Location: SKBO.Airport, FO
Flight conditions: VMC
Light: Daylight
Aircraft: Widebody; Low Wing; 2 Turbojet Eng
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Flight phase: Initial Approach
ATC / advisory: TRACON SKBO
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Situational Awareness; Communication Breakdown; Confusion; Distraction
Anomaly: Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT
Detector: Automation Aircraft Terrain Warning; Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued Advisory / Alert; Flight Crew Became Reoriented; Flight Crew Took Evasive Action; Flight Crew FLC complied w / Automation / Advisory
Contributing factors: Airport; Environment - Non Weather Related; Human Factors; Procedure
Primary problem: Ambiguous

Narrative: We held at VULAM and then were cleared to intercept the 300 radial BOG inbound to SKBO. There were several other aircraft holding and one aircraft a few miles ahead of us starting their approach. The Controller gave us decreasing speeds to fly until she assigned us 170 KTS at least 15 miles out. She gave us a heading to intercept the LOC [at] and descended us to 12;000 FT and cleared us for the approach. She did not tell us to maintain an altitude until on the LOC. When she cleared us for the approach the pilot not flying cleaned up the approach which deleted visual representation of the BOG VOR. The intercept heading was not getting us to the LOC so we turned 10 degrees more toward the LOC course. At some point we discussed staying at 12;000 FT or descending. We mistakenly decided to start a descent lower. I believe the high airport elevation and the fact that we were at 12;000 FT contributed to a lack of realization that we needed to stay at 12;000 FT until we were closer in on the LOC. We had thoroughly briefed staying at 12;000 FT until over the BOG VOR but since we were not flying to the VOR and we had cleaned up the approach we lost some situational awareness (SA) as to our location relative to the BOG VOR. As we decided to start down toward 10;000 FT we were VMC the entire time and I used VS to start a slow (less than 1;000 FPM) rate of descent. I had the surrounding terrain in sight and I was also watching the aircraft ahead of us on TCAS because we were close in altitude. I had visual of the surrounding terrain at all times and did not think we were descending too rapidly. At approximately 11;000 FT I decided to slow the rate of descent (ROD) more. About this same time the Controller asked us if we were VMC and said she had wanted us to maintain 12;000 FT until we were on the approach. About this same time we received a GPWS terrain warning and I started a slow climb and added a little power due to the fact we had all terrain in sight. We leveled off and intercepted the glide path with no further incidence. We called the ATC facility when we blocked in and they discussed what happened with the Captain. They said there would be no further reports or action taken.This event was caused by a combination of factors which include[flight] crew error and communication problems with ATC. We should have stayed at 12;000 FT until we were past the BOG VOR. I take full responsibility in this mistake and should have kept better situational awareness of my location on the approach. I think it would also be helpful if there was a solid black line under the 12;000 FT description on the approach chart at the BOG VOR. This should be a hard altitude and usually a hard altitude on an approach is underlined in black. We briefed the altitudes on the approach but in hind sight we should have also talked more about what DME to start out of 12;000 FT so that if we weren't over the BOG VOR we would still know where to start our descent.




Synopsis: An air carrier on a vector to intercept the SKBO Runway 31 LOC descended toward 10;000 FT before the BOG VOR but climbed after recieving an EGPWS terrain warning concurrent with an ATC request for current flight conditions.