Date: 201701
Local time of day: 1801-2400
Location: SNA.Tower, CA
Aircraft: Beechcraft Twin Piston Undifferentiated or Other Model
Operator: Personal
Operating under: Part 91
Flight phase: Final Approach
Airspace: Class C SNA
ATC / advisory: Tower SNA
Second aircraft: B737 Undifferentiated or Other Model
Reporter organization: Government
Reporter function: Local
Reporter qualification: Air Traffic Control Fully Certified
Second reporter function: First Officer; Pilot Not Flying
Anomaly: ATC Issue All Types; Conflict Ground Conflict; Less Severe; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural FAR
Detector: Person Flight Crew
When detected: Taxi
Result: Air Traffic Control Provided Assistance; Flight Crew Requested ATC Assistance / Clarification
Contributing factors: Airport; Human Factors; Procedure
Primary problem: Human Factors

Narrative: I was working LC2 when my first aircraft on final a [twin engine Beechcraft]; requested to land Runway 20R. I coordinated with LC1 for this request; he approved it; so I then changed the [twin] to land on the parallel runway. There was a B737 holding between the runways at the time; and it appeared to the B737 pilots that the Baron had overflown the B737. I would recommend that the [twin] pilot had not waited so long to change his flight path. He was given clearance to change runways at about 1 mile final; but was a little slow on the turn; which then made the B737 pilot think that he had been overflown.


Second narrative: We pushed back from the gate and started engines normally; and then were informed that we would have about a 15 minute ATC delay before takeoff. Within a few minutes; we were given taxi instructions by Ground and told to contact Tower. Tower instructed us to taxi across 20L and hold short of 20R. We complied with the instructions and set our parking brake. At that point; I (and shortly later the Captain) noticed a small twin engine aircraft behind us at the 4 o'clock position and we both thought it was landing behind us on 20L. About 10-15 seconds later; we both saw the aircraft land on 20R; and believed the aircraft must have passed over our cockpit to make the landing on 20R. We did not hear any communication from the aircraft because 20L has a different Tower frequency than 20R. The Captain asked Tower if the aircraft passed over the top of us and they replied something like he could not tell from the Tower; but he did not think so. Tower then said that the other aircraft said they would not overfly us (on the sidestep maneuver; I assume). The Captain then told the Tower he was not happy and would be filing a report and wanted the tail number of the other aircraft.I see nothing we could have done to prevent this from occurring. It appears that the other aircraft was given a late side-step maneuver which caused the incident. Obviously; a late runway change like that cannot be allowed to occur.


Synopsis: A Tower Controller and B737 flight crew reported that a twin engine Beechcraft pilot overflew the air carrier aircraft at very low altitude while side-stepping to the parallel runway.