Date: 201704
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Flight conditions: VMC
Weather elements / visibility: 10
Light: Daylight
Aircraft: PC-12
Operator: Air Taxi
Operating under: Part 135
Flight plan: IFR
Mission: Passenger
Flight phase: Taxi
ATC / advisory: Ground ZZZ
Second aircraft: PC-12
Reporter organization: Air Taxi
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Flight Instructor; Flight Crew Instrument
Human factors: Situational Awareness
Second reporter function: Pilot Not Flying; First Officer
Anomaly: Ground Event / Encounter Aircraft
Detector: Person Flight Crew
When detected: Taxi
Result: Aircraft Aircraft Damaged; General Flight Cancelled / Delayed; General Maintenance Action
Contributing factors: Airport; Human Factors
Primary problem: Human Factors

Narrative: While taxiing out of the ramp area; I was taxiing the aircraft on the yellow ramp center line; we were approaching another aircraft on the right and the captain of that aircraft was standing by his airplane so he could make sure we had enough wingtip clearance. As we approached my First Officer informed me that I was clear and the captain of the other aircraft gave us a thumbs up which I took to mean we were all clear. I continued to taxi forward and did not change the direction of taxi at all. The right wingtip/radar dome of our airplane hit the spinner cone of the other airplane and we came to a stop. I set the parking break and we ran the engine shutdown checklist. I informed our passengers that we would be vacating the airplane and to please follow my first officer back inside. The ramp space that we operate out of is very tight and often congested to begin with. The painted T's that we use for reference to park the airplane should be moved back. I shouldn't trust the centerline because it doesn't always mean we are clear. Also even if there is a wing walker I should always rely on myself to make sure we are clear.


Second narrative: On taxi out from the ramp to the runway the right wingtip fiberglass radar dome cover impacted the nose cone of the parked aircraft. Damage: minimal. Replacement of fiberglass radar dome cover and then replacement of chrome spinner cone. The problem arose because of poor crew coordination. As the first officer I was completely focused on the other captain that was on the ramp giving a thumbs up signal that we had proper clearance to taxi by his aircraft. This individual misjudged the clearance limit and I was so focused on him that I was not observing the actual wing tip to spinner cone distance or clearance. The main contributing factor here is poor ramp design for the intended purposes. This is a high volume ramp area that was originally designed to be used by small single engine piston powered aircraft. High usage by larger turbine aircraft combined with anyone parking another such aircraft just forward of their intended position combined with the outbound aircraft being just four to five inches off centerline you have then lost any cushion or clearance. Another contributing factor is there was no marshal person for our outbound movement.


Synopsis: PC-12 flight crew reported wingtip damage during taxi after receiving a thumbs up from a Captain on the ground regarding clearance with the aircraft he was preflighting.