Date: 201510
Local time of day: 0001-0600
Location: LAS.Airport, NV
Light: Night
Aircraft: Large Transport; Low Wing; 2 Turbojet Eng
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Landing
ATC / advisory: Tower LAS
Second aircraft: Medium Large Transport; Low Wing; 2 Turbojet Eng
Reporter organization: Government
Reporter function: Local
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Communication Breakdown; Distraction; Situational Awareness; Time Pressure; Workload
Anomaly: ATC Issue All Types; Conflict Ground Conflict; Less Severe; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Air Traffic Control
When detected: Taxi
Result: Air Traffic Control Provided Assistance
Contributing factors: Airport; Procedure; Staffing
Primary problem: Procedure

Narrative: ADW (procedure for reduced arrival/departure spacing) in use. I need to land Runway 19R. Local Control 1 needs to land Runway 25L. Reduced separation approved for Runway 25R departures. Aircraft X inbound to Runway 19R and cleared to land. Several traffic calls made to Aircraft X for helicopter tour flights in close proximity to the Runway 19R finals. When Aircraft X was about 1 1/2 mile final I checked the ASDE-X to see if Local Control 1 had any traffic waiting to depart but they did not (I was going to remind them that Aircraft X was a type aircraft requiring and additional spacing). I watched Aircraft X rollout and issued exiting and crossing instructions. About this time the ground controller approached and said they thought Local Control 1 may have just landed Runway 25R simultaneous to my Runway 19R operation. I looked at the ASDE-X and saw Aircraft Y tagged as an arrival about to exit Runway 25R at a taxiway. Aircraft X had already exited Runway 19R and the conflict had passed. The ASDE-X did not alarm. LC1 is allowed to land Runway 25R but when they do 7110.65 rules apply and ADW is suspended for that operation. I had no idea that Local Control 1 had changed Aircraft Y from landing Runway 25L to Runway 25R. There was no coordination done. It is not my purview to watch the Local Control 1 finals. The onus is on the Local Control 1 controller to coordinate. In this instance; I was watching my traffic; and the helicopters and was unaware of local Control 1's actions. I think that if the Local assist position had been staffed this would have been caught. That being said; every night we get an arrival rush and Approach Control jams the finals to Runway 25L with minimal spacing; over-takes etc. while the off-load Runway 19R sits unused. The Local Control 1 is busy massaging the Runway 25L finals to save go-arounds including as in this case occasionally side-stepping an arrival from Runway 25L to Runway 25R. If Approach Control would give more spacing to Runway 25L and use the off-load runway with better efficiency would reduce the complexity.




Synopsis: Local Controller at LAS reported of aircraft landing on Runway 19R at the same time as another aircraft landed on Runway 25R. These runways intersect at the departure end. The Local Controller working Runways 25L and 25R failed to advise the Local Controller working Runways 19L and 19R of their traffic which is a required advisement.