Light Transport; Low Wing; 2 Turbojet Eng
Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Flight Crew Last 90 Days 50; Flight Crew Total 5000; Flight Crew Type 40
Situational Awareness; Confusion; Communication Breakdown
ATC Issue All Types; Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT
Air Traffic Control Issued New Clearance; Flight Crew Took Evasive Action; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Became Reoriented
Environment - Non Weather Related; Human Factors; Procedure
During the initial descent we were given a crossing restriction of 'cross 50 NM northwest of APA at 15;000.' I read back the clearance and continued the descent. As we were completing the descent nearing Denver Approach's airspace we realized that we were descending to 15;000 and Longs Peak was straight ahead of us approximately 20 NM. Our local knowledge of the mountains we knew this mountain to be over 14;000 FT tall. The Captain leveled off our descent at 16;000 FT MSL. The Captain asked me to confirm our altitude with ATC. We made an attempt to confirm but due to frequency congestion we received no response. A few transmissions later by ATC we were told to climb and maintain 17;000. We complied and had already started a slow climb. During this entire event we had terrain in sight and no immediate action was required to avoid the terrain. Upon landing the Captain called Denver Center and spoke with the Center and he advised us that the Controller cleared the aircraft to 'cross 50 NM northwest of APA at 17;000.' I read back the 'cross 50 northwest at 15;000.' However the Controller did not catch our incorrect read back of the altitude assignment.It would seem the Captain's attention to local flight patterns caught the problem before ATC notified us. Secondly; if we were able to confirm our altitude clearance as we had tried before the deviation we could have leveled off at the correct altitude. The frequency congestion delayed our ability to clarify the clearance with ATC.
A pilot read back a clearance to cross 50 northwest of APA at 15;000 FT but the the crew leveled at 16;000 FT because of high terrain knowledge and was then notified by ATC that the descent clearance was to 17;000 FT.