Date: 201601
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: VMC
Weather elements / visibility: 30
Light: Daylight
Aircraft: Light Transport; High Wing; 2 Turboprop Eng
Operator: Military
Operating under: Part 91
Flight plan: None
Mission: Skydiving
Flight phase: Takeoff / Launch
ATC / advisory: CTAF ZZZ
Second aircraft: RV-6
Aircraft component: Air/Ground Communication
Component problem: Improperly Operated
Reporter organization: Military
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Flight Instructor; Flight Crew Flight Engineer; Flight Crew Air Transport Pilot (ATP)
Human factors: Communication Breakdown; Situational Awareness
Anomaly: Conflict Ground Conflict; Critical; Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Other / Unknown
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Took Evasive Action
Contributing factors: Airport; Human Factors; Procedure
Primary problem: Ambiguous

Narrative: During parachute operations for military parachute training flight; we landed for fuel and a military jumper delay. CTAF was in radio #1; with the military ground station on the #2 radio. Due to some difficulty in hearing [military ground station]; radio #1 volume was turned down.We picked up jumpers and taxied to Runway 02. We monitored CTAF and made a call taxiing to 02; then departing 02. On the taxiway 90 degrees to the runway at the arrival end; I called 'clear left' for traffic; and the pilot in the right seat called 'clear right. I checked left and right; advanced the propellers to high RPM; and placed the left engine in flight idle as I completed the turn onto the runway.At [this airport]; jump traffic departs 02 and lands 20; opposite direction. Traffic on final is generally expected high; as the base leg to final is often 5;000 feet or higher; as arriving traffic arrives on a steep descent from the jump run. I checked opposite-direction final and placed the right power lever in flight idle; then advanced both engines to 50 PSI and began the takeoff roll.At approximately 60 knots; I noticed something on the runway; though it was hard to see. The right seat pilot noted it too; and shortly thereafter we were able to see a small airplane moving opposite direction; on the surface. We were unable to determine if it was landing; taking off; or taxiing. It was grey; without lights; and a checkerboard paint scheme that made it hard to see and broke up the outline. It was low to the ground with short conventional landing gear. When we both recognized the traffic; the right seat pilot called out 'abort; abort; abort.' I was unable to determine distance to the other aircraft or to know whether we could stop in time; given decreasing distance; and an accelerate-stop distance that would have taken us well down the runway. I declined to reject the takeoff; and instead angled the aircraft left. At that point we were at rotation speed. The right seat pilot pulled back on the control wheel as we approached the runway edge; and we became airborne. The other airplane turned off the runway at the runway midfield access intersection. We climbed out normally.The right seat pilot commented that it was the closest call he had experienced in [many] years; and was clearly shaken. He called on the radio; but received no response. He checked the volume; and found that he had lowered it when we taxied to the ramp on the previous flight. When the right seat pilot called out 'why didn't you make any position reports?' the pilot of the aircraft radioed back that he had made numerous calls. This was confirmed by company aircraft on the company frequency. None of that information had been relayed to us; and we did not hear the pilot's call; due to the decreased radio volume. We did not see the RV pilot; either due to looking for traffic at the usual higher approach angle for [this airport]; or because he was already on the ground. Unlighted and with a paint scheme that made identification difficult (and no lighting); we did not see that aircraft.The RV pilot apparently made no effort to take evasive action or to go around. I elected to deviate to the left during the takeoff roll; rather than right for two reasons: the runway access taxiway exited to our right and it appeared that the aircraft was attempting to vacate there. The other reason I elected to deviate to the left on Runway 02 was that it presented no immediate obstacles; a flat dirt area outside the runway in the event we left the pavement on the ground; and no obstacles beyond; for the climb. A deviation to our right would have turned us toward waiting jumpers; the exiting aircraft; aircraft on the ramp; and the maintenance hangar and trees.I intend to modify my departure procedures during jump operations at [this airport] to include a radio squelch check to determine volume during taxi; use of landing lights during the takeoff roll; and a more thorough scan of opposing final approach traffic (high; low and on the ground); to ensure this does not happen again. It has been brought to the attention of management personnel at [the airport]; including the Chief Pilot.




Synopsis: The pilot of a sky diving aircraft reported a ground conflict during takeoff due to improper CTAF operations. The flight crew did not realize that the communication radio in use had the volume set very low.