Medium Transport; High Wing; 2 Turboprop Eng
Situational Awareness
No Specific Anomaly Occurred All Types
Flight Crew Took Evasive Action; Flight Crew Became Reoriented
Chart Or Publication; Human Factors; Aircraft; Airport
We were commencing the Roaring Fork Visual into ASE via Ruedi Reservoir to Runway 15 and circling to Runway 33. I had set and selected 11;500 (published recommended altitude just north of Ruedi Reservoir). As we were coming up over Ruedi Reservoir we were descending through approximately 12;500 +/- when ATC stated they were receiving a low altitude alert and to verify terrain in sight. We had the terrain in sight and as we replied to ATC we simultaneously received a GPWS warning at which point I had disconnected the autopilot and stopped the descent showing approximately a 200 FPM climb initially; which cancelled the GPWS warning. NOTE: As we were descending towards 11;500; the vertical airspeed was approximately 2;000 - 2;500 FPM. That may have contributed to the GPWS warning (our vertical speed was too excessive at that point on the chart even though we were above the recommended altitude). If conducting the Roaring Fork Visual via Ruedi Reservoir again; I would only commence it if high rates of descent were not needed to in order to get to recommended altitudes to set up for the final descent into ASE. The other course of action would be to approach ASE from the north via a more direct course via the localizer course so as to not fly below published altitudes if commencing a visual approach.
We were cleared for the visual approach; circle to land Runway 33; into Aspen by approach. We began our descent into Aspen East of Red Table VOR (DBL) and turned south for the runway; relatively close to the WOKUV Intersection. When we made the turn; we had a clear visual reference to the runway the entire time. We began about a 2;000-2;500 FPM descent with 11;500 FT ALT SEL selected; referencing the Roaring Fork Visual; just north of Ruedi Reservoir. We could see all of the terrain in front of us; as well as the runway; when we established our descent. As we crossed the last ridge just north of the reservoir; we received a terrain warning; quickly followed up by a 'Terrain; Pull Up' call. At the same time; we received a call from the Tower; advising us of a low altitude warning. We knew we would clear the ridge with no problems; but the Captain properly complied with the GPWS call; disconnected the autopilot; pulled up; added power. We leveled off; even climbed for a bit; while we passed the ridge and the GPWS was cleared. We then continued our descent into the airport. We think the GPWS was triggered because we had an aggressive descent while flying over ridges that the GPWS sensors cannot see past. I was rather surprised that the GPWS was triggered; simply due to the fact that both the Captain and I were focused on our descent planning into the circle to land and could see the airport during the entire descent. It is no surprise that we have to maneuver aggressively from time to time to get into Aspen. That includes our initial descents when we're visual. I feel that this could have been prevented by either leveling out a little higher north of Ruedi Reservoir and/or managing descent rate a little more conservatively at the top of the descent. Also; the recommended altitude at that point on the Roaring Fork Visual plate says 11;500 FT; which we had as ALT SEL. If descending to 11;500 FT at this point is going to trigger a GPWS and a low altitude warning from the Tower; then this plate should be revised.
Flight crew reports ATC terrain warning and GPWS warning while descending visually into ASE from over Ruedi Reservoir using the Roaring Fork Visual for guidance. The high descent rate was thought to have caused the GPWS warning.