Date: 201811
Local time of day: 1201-1800
Location: SPF.Airport, SD
Weather elements / visibility: 10
Aircraft: Small Transport
Operator: Personal
Operating under: Part 91
Flight plan: DVFR
Mission: Personal
Flight phase: Climb
Airspace: Class E RCA
ATC / advisory: TRACON RCA
Aircraft component: Air/Ground Communication
Reporter organization: Personal
Reporter function: Pilot Flying; Single Pilot
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Human factors: Confusion; Time Pressure; Communication Breakdown
Anomaly: ATC Issue All Types; Aircraft Equipment Problem Less Severe; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter CFTT / CFIT; Inflight Event / Encounter VFR In IMC
Detector: Automation Aircraft Terrain Warning; Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Aircraft Equipment Problem Dissipated; Flight Crew Overcame Equipment Problem; Flight Crew Took Evasive Action
Contributing factors: Procedure; Aircraft; Human Factors
Primary problem: Ambiguous

Narrative: I was cleared (via radio phone patch) to LAR as filed (direct) climb; maintain 6;000; expect FL260 10 min after departure. On departure [frequency]. The cloud bases were around 7;000 feet MSL in our direction of flight. I did not file; nor was I assigned the graphical RNAV-ODP. I departed Runway 31 and climbed to 500 AGL; started a left turn to the south-west and completed the normal acceleration schedule while putting the wing into cruise-climb mode in steps. After announcing away and clear on UNICOM; I switched to 119.5 and contacted Ellsworth Departure at around 4;500 in the climb. I got a very clear and loud 'meow' in response and then silence. I tried them again a couple seconds later and got the same cat-like response. I asked the pilot sitting next to me if heard the same thing and he was looking quite confused and said he did (it sounded like a person imitating a cat). Later my 3 passengers (with headsets) said they heard the cat-like sound also. I leveled off at 6;000 and pulled the power back to keep under 250 KTS IAS (my Vmo); switched to COM Number 2 and tried again...no controller; just a 'meow.' We saw the 6;900 foot mountains approaching; there were certainly a few places I could sneak between the peaks while staying at 6;000; but I would have had to change heading substantially. I was unsure what to do as my clearance was 6;000 and 10 minutes (the lost com climb instruction) had not passed. At that time; my TAWS system alarmed. I added power; turned on the anti-icing equipment and climbed into the clouds. While climbing I switched to 121.5 and called in the blind on Guard asking for an alternate frequency. To my surprise; Ellsworth answered and advised me to switch to 119.5. I explained why I was above my 6;000 foot assigned altitude and that I had been unable to raise them on 119.5. He had me try again (now at about 10;000 feet) and it worked fine. The pilot sitting next to me and I both had cross-checked our frequencies and they were not in error. I also was just using the 'flip-flop' feature on the GNS430W so I can't explain why it didn't work earlier but then worked at 10;000 unless a repeater was broken resulting in poor reception; or something was wrong with both of my radios that then fixed itself. I have no explanation for the cat sounds on the radio...it was not radio interference/static; it sounded like a person having some fun with me. I do not know what I should have done. I could have turned back to the field; orbited and tried the phone patch again; I could have stayed VMC; turned around and returned to land. I could have stayed at 6;000 and started scud-running through the mountains while trying to raise Departure Control but I wasn't sure I'd ever get in touch with Ellsworth and it looked pretty dicey ahead of me at 6;000. I elected to climb before 10 minutes had passed in response to my TAWS alert. Should I have done the ODP? Since it only gets me to 4;500; would it have helped? Any idea on the cat sound? I wonder if I incorrectly wrote down my initial climb altitude limit (could it have been 16;000?) but I believe I read back 6;000 and the guy sitting next to me heard the same (I was on a phone patch and my radio recorder didn't go back that far to check). But in thinking about it; if I'm cleared direct to the south-east at 6;000 MSL traveling 250 KTS IAS; 10 minutes before allowable lost-com climb would put me into the terrain shortly after takeoff; so I really don't understand the whole situation. Obviously if I had made contact with Ellsworth right after taking off; they would have cleared me higher and it would have been a non-issue. I know these reports are not supposed to be for intentional deviations and I made the decision to climb early; but as I stated; I don't know what the right answer was in this situation.




Synopsis: Turboprop pilot reported a communication breakdown with ATC led to an altitude deviation due to approaching terrain.