Narrative:

I was pilot flying into mtpp. Weather was day VMC with good visibility. Captain and I had briefed that we would fly the approach to [runway] 10; then circle to land [runway] 28. We discussed circling altitude and the fact that the glide path on the instrument approach to [runway] 28 was steeper than average. Also [we] discussed that the PAPI's were hard to see above 1;000 ft; so the RNAV glidepath would be a back up once we were established on final. We were anticipating the DME arc to 10; and I believe it was over savar that we were told to proceed direct irdas by ATC. The captain did not hear ATC's garbled transmission clearly; and while ATC was phonetically spelling the name of the fix; I typed it in so as to turn in the correct direction. The captain then programmed the remainder of the approach into the FMC. Between irdas and rikot I descended from 4;500 ft to 4;000 ft and we received a GPWS warning. Although I had visual contact with the terrain and saw no threat; I initiated a climb and the warning immediately ceased. Continued the approach and landed uneventfully.I believe that an earlier confirmation of the approach to be flown would have helped us to be better prepared. We did not expect to fly the full RNAV approach to [runway] 28; and that put us behind in preparing to fly the approach. The difficulty of communications created a higher workload; between the controller's heavily accented english and the poor quality of the radio transmissions overall. Being cleared direct irdas left a route discontinuity; since the transition was not selected and the intermediate step down altitudes between irdas and rikot were then not on the FMC. In the future; verify that all altitudes on the electronic chart are represented on the FMC.

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Original NASA ASRS Text

Title: B757 flight crew reports descending early on the RNAV Runway 28 to MTPP. The clearance direct IRDAS is received late and the transition from IRDAS is not selected in the FMC eliminating two step down fixes and results in a terrain warning.

Narrative: I was pilot flying into MTPP. Weather was day VMC with good visibility. Captain and I had briefed that we would fly the approach to [Runway] 10; then circle to land [Runway] 28. We discussed circling altitude and the fact that the glide path on the instrument approach to [Runway] 28 was steeper than average. Also [we] discussed that the PAPI's were hard to see above 1;000 FT; so the RNAV glidepath would be a back up once we were established on final. We were anticipating the DME arc to 10; and I believe it was over SAVAR that we were told to proceed direct IRDAS by ATC. The Captain did not hear ATC's garbled transmission clearly; and while ATC was phonetically spelling the name of the fix; I typed it in so as to turn in the correct direction. The Captain then programmed the remainder of the approach into the FMC. Between IRDAS and RIKOT I descended from 4;500 FT to 4;000 FT and we received a GPWS warning. Although I had visual contact with the terrain and saw no threat; I initiated a climb and the warning immediately ceased. Continued the approach and landed uneventfully.I believe that an earlier confirmation of the approach to be flown would have helped us to be better prepared. We did not expect to fly the full RNAV approach to [Runway] 28; and that put us behind in preparing to fly the approach. The difficulty of communications created a higher workload; between the Controller's heavily accented English and the poor quality of the radio transmissions overall. Being cleared direct IRDAS left a route discontinuity; since the transition was not selected and the intermediate step down altitudes between IRDAS and RIKOT were then not on the FMC. In the future; verify that all altitudes on the electronic chart are represented on the FMC.

Data retrieved from NASA's ASRS site as of July 2013 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.