Flight Crew Air Transport Pilot (ATP)
Communication Breakdown
Conflict Ground Conflict; Critical
General Flight Cancelled / Delayed
Airport
Preparing to taxi to Runway 01 at SGU; an uncontrolled airport; I as pilot monitoring began monitoring the CTAF frequency. Hearing nothing upon completing our final taxi check; I made a radio call on the correct frequency indicating our position and type of aircraft and that we would be taxing for takeoff on Runway 01 via A. The wind was reported as calm. Hearing no one else on the CTAF; we began our taxi as briefed and broadcast. I placed the CTAF frequency as active in the number 2 radio and selected the Captain to hear and respond to that frequency. Meanwhile; I selected ARTCC as the active in number 1 radio; selected 2 in standby so I could also hear CTAF; and then picked up the clearance.Since we heard no one else on frequency; I advised ATC that we were ready for departure on Runway 01. We were released for departure. Upon coming back to frequency; I switched radio number 1 back to CTAF and ensured both pilots were listening and tuned for that frequency. After completing the final checklist; I made another CTAF announcement that we were; 'taking Runway 01 for departure; climbing to 13;000 via the SID.' Hearing nothing in response; we proceeded onto the runway; and as we aligned with centerline; the Captain stated that he saw an aircraft rotating on the same pavement; opposite direction on Runway 19. I made no less than four immediate queries to the Cessna aircraft as he flew overhead. I asked if he was on CTAF; if his radio was broken; and also to identify himself via callsign. There was no reply until he was out of sight. Having turned crosswind; he made a position announcement. I then queried him again as before but he simply replied that there was another aircraft waiting to takeoff on Runway 19 and that he was exiting the pattern to the east.  Immediately; the other aircraft spoke on CTAF and said that he was holding short of the runway still and that it was clear. We then departed without further incident.The cause of this event is the lack of communication from general aviation pilots at a non-towered uncontrolled airport.  I made several checks that our CTAF frequency was in fact correct and that the volumes were turned up. Runway 01/19 at SGU is 9300 feet long and due to the crown and general slope of the pavement; small light colored aircraft are extremely difficult to see at that distance. In fact; the Cessna did not even become visible until rotation whereby his undercarriage contrasted sufficiently with the runway in order to be seen. SGU is known to be hazardous due to the volume of general aviation traffic mixed with turbojet aircraft. The lack of situational awareness and cavalier radio attitude shown in this instance is at best alarming and at worst recklessly negligent. A contributing factor may have been that since we heard no other traffic on frequency; we made the assumption that we were in fact alone at the airport and did not adequately clear the far end; however as aforementioned; small aircraft are near impossible to see against the mountainous horizon at that distance.SGU is well-known by part 121 pilots who frequent it; as an extremely hazardous airport due to the lack of any ATC controlling presence including radar. The airport has significant traffic volume that it is not atypical to have as many as four or five aircraft in the traffic pattern at one time. This is busy for any general aviation airport but the introduction of turbojet traffic makes for increasing hazards. As a personal note; I have never without exaggeration spoken to a fellow 121 pilot about SGU who hasn't agreed that the field should be towered and controlled at least on a limited basis. I also think that despite terrain surrounding the field; the FAA would be wise in designating a specific runway as the 'preferred' calm wind runway. I have reviewed our company notes on the field and found no such designation.  My suggestion would be to designate Runway 19 for this purpose.
Air carrier First Officer reported proceeding on to the runway at a SGU non-towered airport and observing an aircraft that had not been transmitting on CTAF departing the opposite direction runway.