Date: 201401
Local time of day: 1801-2400
Location: TUS.Airport, AZ
Flight conditions: VMC
Light: Night
Aircraft: Baron 58/58TC
Operator: Personal
Operating under: Part 91
Flight plan: VFR
Mission: Training
Flight phase: Descent
Airspace: Class C TUS
ATC / advisory: TRACON TUS
Reporter organization: Personal
Reporter function: Single Pilot; Pilot Flying
Reporter qualification: Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Flight Instructor; Flight Crew Flight Engineer; Flight Crew Air Transport Pilot (ATP)
Anomaly: ATC Issue All Types; Inflight Event / Encounter CFTT / CFIT
Detector: Automation Aircraft Other Automation; Person Flight Crew
When detected: In-flight
Result: Flight Crew Became Reoriented; Flight Crew Took Evasive Action
Contributing factors: Procedure; Human Factors
Primary problem: Human Factors

Narrative: Was flying a BE58P to TUS and I am not familiar with this area; but was aware of mountainous terrain surrounding TUS. It was approximately 1 hour after sunset and completely dark with no moon and clear skies. We were at 8;500 FT MSL and contacted Tucson approximately 30 NM southeast of TUS. Tucson Approach told us to proceed to 'right downwind for Runway 11R; maintain at or above 4;000 FT.' I was hesitant to start my descent so soon because I believed that terrain could still be a factor because all we could see was blackness. In fact; I intentionally went to Foreflight on my iPad and selected 'Hazard Advisor' to depict any threatening terrain. During the descent to 4;000 FT; while briefing the visual approach and at approximately 6;300 FT MSL; the pop-up terrain feature on my Garmin G600 activated and the audio 'terrain' annunciated. I immediately applied takeoff thrust and raised the nose to achieve best angle of climb airspeed until I had assured myself of terrain separation. It is significant to note that I had only recently upgraded my avionics to include terrain warning. In hindsight; I recognize my errors. I was the sole person responsible for the safety of my aircraft. I was the pilot in command and flying VFR in VMC conditions. I was invited by ATC to descend to 4;000 FT MSL. I was aware that terrain could have been a factor. Normally; I would not have descended so soon; but since ATC had invited me down to 4;000 FT; I felt that it gave me some type of assurance for terrain clearance. Why else would ATC give me an altitude limit above the traffic pattern if it wasn't for terrain? After reviewing the ground track (after landing) it seems that there was a 6;189 FT peak (Mt. Fagan) that I was descending into and I was only about 120 FT from impact when my terrain alert activated. There were no warning transmissions from Tucson Approach. The lesson I learned was how easily it is to be lulled into a false sense of security from a seemingly legitimate source. ATC invited me down to 4;000 FT and I took the bait when I shouldn't have. I should have maintained my own standards and techniques despite the 'assurances' of ATC.




Synopsis: BE58 pilot 30 NM southeast of TUS at 8;500 FT is told by Approach to maintain at or above 4;000 FT and join the right downwind for Runway 11R. Believing this to be a clearance to 4;000 FT a descent is initiated until a terrain warning is annunciated in the aircraft at 6;300 FT and a climb commenced.