Light Transport
Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Communication Breakdown; Confusion; Distraction; Situational Awareness
Conflict Airborne Conflict; Conflict Ground Conflict; Critical; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued New Clearance; Air Traffic Control Separated Traffic; Flight Crew Took Evasive Action; Flight Crew Executed Go Around / Missed Approach
Human Factors
On a Visual Approach Tower instructed another aircraft to 'line up and wait' on an intersecting runway.  On very short final I heard [callsign] 'stop' repeatedly from the Controller. I scanned the airport environment and saw what I believe was a small aircraft moving from my right down the intersecting runway toward the intersection to our runway.  While in the landing flare I called for a go-around immediately before the Controller said '... go-around'. Immediately after I heard the Controller; I said 'go-around' 3 times in rapid succession as the pilot flying was simultaneously executing the go-around. Once climbing I responded to that controller that we were going around.  From my perspective we would climb over the other aircraft.  Once we began to climb; I lost sight of the aircraft as it was moving to my left. We coordinated with the tower to make right traffic and remain with him. We made an uneventful visual pattern and landed.There was nothing we could have done to prevent as we were non-offending aircraft. The FAA has repeatedly made incursions a priority for safety information. I don't know how else to ensure people remain vigilant when receiving this type of ATC instruction.
As we were beginning to flare for landing after being cleared to land; we heard the Tower Controller yell repeatedly on the frequency for another aircraft to stop. It was then that we saw a high wing single engine aircraft rolling for takeoff on the intersecting runway and rapidly approaching the intersection. I began pitching up and adding power at the same time the First Officer called for a go-around and simultaneously we heard the Tower Controller calling '...Go-Around.'  As we climbed out; we crossed above and over the high wing aircraft who appeared to be beginning his rotation for takeoff. We then proceeded with a normal go-around and told the Tower we could enter a visual traffic pattern for a return to landing.Prevention would have been out of the control of our crew or ATC. Prevention would rest with the crew of the offending aircraft by being more alert and assuring a proper takeoff clearance prior to departing.
Flight crew on landing flare reported an aircraft took off from an intersecting departure towards their path so they initiated a go-around the same time MMU ATC told them to go-around. The reporters said the other traffic had been instructed to taxi into position and hold.