On August 16, 2007, at 1257 Pacific Daylight time, a runway incursion occurred involving West Jet (WJA) flight 900 and Northwest Airlines (NWA) flight 180 at Los Angeles International Airport, Los Angeles, California during daytime visual flight rules conditions. WJA900 landed runway 24R and exited on reverse taxiway Y. While exiting, the flight crew of WJA 900 switched to the north ground control (GC2) frequency without instruction and advised they were on the reverse taxiway, Y, for gate 35. The GC2 controller thought that the WJA aircraft was south of runway 24L and instructed the flight to taxi via taxiway E to the gate. When WJA900 was approaching runway 24L on the reverse taxiway, the pilot saw NWA180 begin its take-off roll and questioned whether or not they had clearance to cross the runway. The GC2 controller, realizing WJA 900 had not received a crossing clearance, stopped WJA900 from crossing the runway. The Airport Movement Area Safety System (AMASS) alerted and separation was lost. According to the AMASS data, NWA180 passed within 37 feet of the WJA 900. The FAA classified this incident as a controller operational error, a pilot deviation, and a runway incursion.

According to the North Local Controller (LC2), he stated that he took the LC2 position when WJA900 was on a 2 mile final for runway 24R. He then instructed NWA180 to taxi onto runway 24L, conducted some coordination, and then cleared NWA180 for takeoff. As he was looking at the tower radar display to determine the next arrival aircraft, he heard the AMASS alert: Warning, runway occupied. He looked at the aircraft involved (WJA900 and NWA180) and saw WJA900 stopped on taxiway Y short of runway 24L but across the hold bars. NWA180 appeared to be past V1 speed so he allowed the aircraft to continue on departure roll. He stated that he did not recall receiving any verbal coordination from GC2 about crossing runway 24L.

According to the North Ground Controller (GC2), he stated that when WJA900 made initial contact on the GC2 frequency, he looked at the airplane. The pilot advised they were on taxiway Y and were going to gate 35. The GC2 controller stated that he looked from the airplane to the gate and verified the gate available then scanned back to the airplane to determine the appropriate taxi route. Seeing no traffic between WJA900 and the gate, he told him to taxi to the gate. Immediately after issuing the taxi instructions to WJA900, he scanned west for conflicting traffic on the taxiway and noted there was an America West jet and issued a sequence to those crews. The GC2 stated that he did not look to the approach end of runway 24L and did not coordinate with LC2, as he did not recognize that WJA900 was north of runway 24L, needing to cross the active runway.

The GC2 controller stated that the training he received for that type of situation was to ask the LC2 to confirm that the flight had been cleared to cross the runway. In this incident, he stated he did not do that because he did not recognize that WJA900 was north of runway 24L. He added that it was not a willful breaking of the rules. He did not believe he was crossing the aircraft.


The Los Angeles Air Traffic Control Tower is a Level 12 ATC facility. The tower is centrally located on the airport between the north and south complexes. The tower can accommodate up to 13 positions; 2 local control (LC1/LC2), 2 local assist (LA1/LA2), 3 ground control (GC1/GC2/GC3), 2 clearance delivery (CD1/CD2), 1 helicopter position (HC), 1 traffic management coordinator (TM), and 2 supervisors (AS1/AS2).

On the day of the incursion, LAX was in a west configuration, and the inboard runways, 24L and 25R, were in use for arriving and departing aircraft. The north complex was landing and departing runway 24R/24L and the south complex was landing and departing runway 25R/25L.


AMASS is a computer software enhancement to the airport surface detection equipment (ASDE). The system provides logic predicting the path of aircraft landing and/or departing, and aircraft and/or vehicle movements on runways. Visual and auditory alerts are activated when logic projects a potential collision. AMASS alerts controllers to a potential collision when an aircraft or vehicle is occupying a runway and when arriving or departing aircraft cross a certain threshold or attain a certain speed. The system works by processing surveillance data from ground radar, and then predicting possible conflicts based on the position, velocity, and acceleration of arriving and departing aircraft and vehicles.

Use your browsers 'back' function to return to synopsis
Return to Query Page