Date: 201912
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Weather elements / visibility: Snow; 0.4
Aircraft: Beechjet 400
Operator: Air Taxi
Operating under: Part 91
Flight plan: IFR
Mission: Ferry / Re-Positioning
Flight phase: Takeoff / Launch
ATC / advisory: Center ZZZ
Reporter organization: Air Taxi
Reporter function: Captain
Reporter qualification: Flight Crew Glider; Flight Crew Flight Instructor; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Sea; Flight Crew Rotorcraft; Flight Crew Instrument
Human factors: Situational Awareness; Communication Breakdown
Second reporter function: First Officer
Anomaly: Conflict Ground Conflict; Critical; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance; Ground Incursion Runway; Inflight Event / Encounter Weather / Turbulence
Detector: Person Flight Crew
When detected: In-flight
Contributing factors: Procedure; Weather; Airport; Human Factors
Primary problem: Human Factors

Narrative: We flew from ZZZ to San Antonio today; and after landing at San Antonio; we were advised on the phone by ZZZ Center that the ZZZ Airport Authority believed we had improperly taken off using a closed runway.ZZZ Airport is non-towered and had a NOTAM published that Runway XX/XY was closed except with 15 minutes [of] prior permission on [the] CTAF/UNICOM. There was snow removal equipment in use on the airfield. We spoke with the FBO personnel and told them we were going to start; taxi; and takeoff. We immediately walked to the plane; parked about 15 yards away; completed our preflight; started engines; and an FBO employee helped direct surface vehicles out of the way so we could taxi. We were monitoring ZZZ Center on one radio and CTAF on the other. I heard the First Officer transmit on CTAF that we were taxiing for takeoff on Runway XX. While taxiing we heard an airliner communicating with ZZZ Center regarding their status on the deicing pad and discussing when they would be ready to takeoff. We did not need to deice our plane so we taxied directly to the approach end of Runway XX. After completing the taxi checklist; the First Officer contacted ZZZ Center and notified them that we were holding short of the runway for takeoff and asked for our IFR clearance. The radios and interphone were quite busy with aircraft diverting to alternates; communicating their deicing status; unrelated communications on Center frequency from planes not at ZZZ; and with our clearance request. ZZZ Center gave us our clearance; confirmed that we were ready for immediate release; and then released us for departure on Runway XX. I heard the First Officer call on CTAF that we were taking the runway for departure. We then took off without incident. During climbout I heard a plow driver asking the status of the runway; saying he could not see sufficiently to ensure the entire runway was clear.I later learned during my phone call with ZZZ Center that a snowplow had been near the runway and did not know we were taking off. We also learned that the snowplow drivers were monitoring aircraft status at the deicing pad to help de-conflict plow operations with departure operations. I do not think they saw us taxi out to the runway [as] our route did not go past the deice pad. I concluded later that the plow drivers either did not hear our transmissions on CTAF that we were taxiing and later that we were taking off; or they heard the calls and did not transmit to us the runway status. Or; they did transmit this information and we did not hear them; I do not know which [one] was the case. I assumed that based on our calls on CTAF and lack of departure denial on that frequency; and based on our clearance for immediate departure on that runway by ZZZ Center; that the runway was available for use. I have previously seen NOTAMs such as the one in effect this day; and I will likely see them again. I still am not clear who; on the specified frequency; is the authority for runway use at a non-towered field. But I will never again assume that just because I have an approach clearance or a departure release in such a case that the runway is safe to use. This situation could have ended much worse.


Second narrative: I was second-in-command; SIC; during our departure from ZZZ. We were repositioning under Part 91 with no passengers or cargo to SAT. We were requested to call ZZZ Center when we landed to discuss what apparently resulted in confusion and a complaint from the airport operations people at ZZZ.ZZZ is a busy non-towered airport. CTAF/UNICOM frequency is used by aircraft arriving and departing per non-towered operations; the FBO; and the commercial airport terminal that was expecting to turn a [commercial] flight as soon as it could get into ZZZ. The weather during the time prior to and during our departure fluctuated from 2 miles visibility; to less than [a] mile; ceilings from 300 feet to 1000 feet; and precipitation varied from clear; to flurries; to intermittent heavy snow fall. There were other Part 135 operators queuing up for departure from ZZZ and several of those requested deicing from the FBO. The de-ice crew had a dedicated separate frequency to coordinate sequencing ground movement of aircraft requesting de-icing; which could only be accomplished at the designated location at the commercial terminal pad. In short; the radio coms during the 15-40 minute time from our taxi call to our departure clearance on ZZZ Center frequency was congested and confusing.ZZZ departure procedures require radio contact with ZZZ Center while on the ground to coordinate clearance before commencing a takeoff. Also; [the] FBO requires 15 minutes [of] lead time during snow removal operations to ensure snow removal crews are alerted and clear of the runway for departures and arrivals.Our first attempt to takeoff was thwarted by several arrivals trying to fly the ILS Runway XX and worsening weather conditions. We returned to the FBO. As a break in the weather appeared; we spoke with the FBO personnel and told them we were going to start; taxi; and takeoff. We immediately walked to the plane parked next to the FBO Dispatcher's window; completed our preflight; started engines; and I announced our taxi intentions to Runway XX on CTAF. The FBO replied with their local altimeter setting; yet no announcement of runway snow removal operations.An FBO employee re-directed surface vehicles delivering passengers to other aircraft to allow us to taxi. We were monitoring ZZZ Center on one radio since they directed us to call them for our clearance when we were number 1 for takeoff. I announced on CTAF that we were holding our position short of Runway XX; awaiting clearance. There was increased radio traffic concerning de-icing after the [commercial] flight was ready to depart and was given priority for de-ice equipment; causing consternation among the others waiting. I did not hear calls on CTAF regarding snow plows working on the runway; although I did observe snow plows and blowers clearing the taxiways.The radios were busy with arriving aircraft diverting to alternates and describing weather conditions on final; as well as other communications on Center frequency from planes at close by airports. I called ZZZ Center; they gave us our clearance; confirmed that we were ready for immediate release; and then released us for departure on Runway XX. I announced on CTAF that we were taking Runway XX for departure. We did not hear any radio calls on CTAF from FBO or snow removal crews regarding their presence on the runway. We then took off without incident. We learned later during a phone call with ZZZ Center that a snowplow had been near the runway and did not know we were taking off. Snow intensity had increased and snow crews would not likely have seen us in the takeoff position on Runway XX. We surmised after conversation with ZZZ Center that the plow drivers did not hear our transmissions on CTAF that we were taxiing and later that we were taking off; or they heard the calls and did not transmit to us the runway status; or they were not on the CTAF frequency and might have been on a separate radio net. Again; much [of the] radio traffic on different frequencies made overall 'situation awareness' difficult. I assumed that based on our calls on CTAF and lack of departure denial on that frequency; and based on our clearance for immediate departure on that runway by ZZZ Center; that the runway was available for use.


Synopsis: BE-400 flight crew reported taking off from a runway with snow removal equipment and crew nearby.