case study- loss of situational awareness

RUNNING HEADER: Loss of Situational Awareness 1

Loss of Situational Awareness

Runway Collision of USAir Flight 1493 and SkyWest Flight 5569

NTSB/AAR-91/08

Joshua Hjemvick

Florida Institute of Technology

AHF5402 – Deaton


ABSTRACT

The following case study reviews the National Transportation Safety Board’s

Aviation Accident Report of the collusion of a USAir 737 and a SkyWest Metroliner that

occurred at Los Angeles International Airport, Los Angles, California on February 1, 2991.

The fatal accident generated a lengthy review of air traffic control management procedures

due to the overall loss of situational awareness that contributed to the collusion of the

landing USAir 737 on the same runway which the SkyWest Metroliner was lined up and

waiting for its takeoff clearance. Safety issues reviewed include coordination procedures,

radio monitoring, runway and aircraft lighting, air traffic procedures including controller

workload, and surface monitoring.

RUNNING HEADER: Lapse of Situational Awareness and Runway Incursions 3

The evening of February 1, 1991 likely began as any other for the air traffic

controllers working the evening shift at Los Angeles International Air Traffic Control

Tower, or LAX ATCT. Two other sets of individuals also expected a different outcome of

their evening plans – the crew and passengers of a USAir Flight 1493, a Boeing 737 and the

crew and passengers aboard SkyWest Flight 5569, a Metroliner turboprop. On this

unfortunate evening the SkyWest Metroliner was preparing for an intersection departure

from LAX’s runway 24L and was lined up on the runway centerline awaiting its takeoff

clearance when the USAir 737 collided with it following it’s landing touchdown on the same

runway. This accident caused a total loss of life of thirty-four individuals, including the

Captain and First Officer operating the SkyWest Metroliner and the Captain and one flight

attendant of the USAir 737.

Beyond the two aircraft involved in the accident, LAX ATCT and LAX Terminal Radar

Approach Control, or TRACON, contributed to the generation of casual elements that played

a direct, and indirect, role in the ultimate runway incursion that occurred which developed

into the accident event. While the USAir aircraft was on its initial approach into LAX, the

LAX TRACON Approach Radar 1, AR1, controller instructed USAir Flight 1493 to intercept

the runway 24 right, or RWY24R, instrument landing system (ILS) localizer. Soon after the

cockpit crew made visual contact with LAX, roughly still on a twenty-mile final to RWY24R,

the AR1 controlled re-cleared USAir Flight 1493 for the visual approach to the parallel

runway, runway 24 left, or RWY24L (p. 3). This changed occurred at 1759 local time, 11

minutes following the end of civil twilight for the accident date (p. 13). The flight crew of

USAir Flight 1493, indicating a mild sense of confusion following the visual approach

clearance, queried the AR1 controller seeking confirmation that they had indeed been


cleared for the visual approach to RWY24L – to which the AR1 controller confirmed that

they had indeed been cleared for the visual approach to RWY24L, not RWY24R the initial

runway they had been instructed to fly an ILS approach to. As the aircraft continued its

approach, the AR1 controlled instructed USAir Flight 1493 to contact LAX Tower – this

occurred at 1803:05 local.

Coinciding with the previously referenced approach events for USAir Flight 1493,

SkyWest Flight 5569 was conducting its taxi on the surface of LAX, taxing out for departure.

SkyWest Flight 5569 received initial taxi instructions that would have put the aircraft

departing at the original departure end of RWY24L. However, during its taxi, the crew

solicited from LAX ATCT an intersection departure from a taxiway/runway intersection at

taxiway 45 and RWY24L. Following the request, the local two, or LC2, controller who is

responsible for the north runway complex that includes RWY24L and RWY24R, approved

the request and instructed SkyWest Flight 5569 to taxi into position and hold at RWY24L

intersection 4-5. This occurred at 1803:40 local, incidentally thirty-five seconds after the

USAir 737 was instructed by AR1 to contact LAX Tower. USAir Flight 1493 made its initial

contact with LAX ATCT AT 1805:29, specifically LC2 whose area of responsibility included

runways 24L and 24R, indicating they were “…for the left side, two four left” (p. 5). The

LC2 controller responded back to USAir 1493 at 1805:53, stating “USAir 1493, cleared to

land RWY24L,” which the Captain of USAir 1493 promptly read back confirming the

landing clearance at 1805:55. The First Officer of USAir 1493, the lone surviving flightdeck

crewmember, recalled during post accident interviews to remember the LC2 controller

conducting side conversations with other aircraft under the control of LC2. However, no

other additional instructions were made to either USAir 1943 or SkyWest 5569.


Sadly it was only moments following the final instructions to USAir 1493 that the

737 collided with the stationary SkyWest Metroliner near the middle section of RWY24L.

This accident reflects a number of situational awareness lapses that occurred amongst the

three primary parties – the flightcrews of USAir 1493 and SkyWest 5569 and the air traffic

controller working the LC2 position in the LAX ATCT.

Challenges exist in any operational environment, especially highly dynamic

environments with multiple commands from air traffic control with numerous aircraft in

one’s vicinity. Pilots are well trained to monitor aircraft systems, performance data, and

external cues that help them build a mental picture of the outside environment in which

their aircraft is operating. Consider the fact that the pilots of USAir 1493 were planning and

initially flew an instrument approach to RWY24R, the parallel runway to RWY24L. The

flight crew was also not on tower frequency when the LC2 position instructed SkyWest

5569 into position and hold at intersection 45 on RWY24L. This is only one instance of a

lack of external information regarding the reality that existed on RWY24L during the final

stages of USAir 1493’s final approach. Additionally, the SkyWest crew should have also

been actively listening to ATC conversation and instructions directed at other aircraft in an

effort to build a greater mental picture of the outside environment, especially the

environment that is occurring behind one’s aircraft and even more especially considering

that one is operating on an active runway. A great deal of information can be garnered from

the external vocal cues directed to other aircraft that pilots can use to develop awareness

of what other aircraft are doing or instructed to do around their aircraft.

Beyond the pilot perspective, the air traffic controller working at the LC2 position

experienced a sever lapse of situational awareness. The controller’s responsibility in this


position includes maintaining separation of departing and arriving aircraft on either the

RWY24L or RWY24R runways. Accordingly, the controller is responsible for all traffic

movement on these two runways including takeoff and landing clearances. During the

NTSB’s investigation it was found that the LC2 controller developed a loss of situational

awareness following the instruction of SkyWest 5569 to position and hold at RWY24L at

intersection 45 as she began to search for flight progress strips for two aircraft that would

be planning a departure from the full-length RW24L (p. 51). This drew the LC2 controller’s

attention away from the more pressing task of insuring aircraft separation between the

inbound USAir 737 and the SkyWest Metroliner that was remaining stationary nearly

midway down the length of RWY24L. Additionally the LAX ATCT was equipped with

surface radar technology that should have increased the controller’s awareness of aircraft

position on the airport surface (p. 18). Following the accident the NTSB reviewed the

controller’s training records and found that just six weeks prior to the accident that the

controller received an over-the-shoulder evaluation from a supervisor. Conclusions of the

supervisor’s evaluation included:

1. A loss of awareness of aircraft separation

2. Misidentification of an aircraft by use of an incorrect call sign

3. Failure to complete two required coordination with other controllers

4. Failure to issue a required advisory to an aircraft. (p. 58)

Of the four findings during the review of the controller’s recent evaluation, the most glaring

lapse is the loss of awareness of aircraft separation. Without question the runway incursion

that occurred is a loss of separation.


Ultimately the NTSB’s findings regarding this accident were very firming placed on

the controller’s lapse of situational awareness, including the following conclusions:

Operating procedures at the LAX ATCT did not provide redundancy comparable to

the FAA’s National Operating Position Standards, which required the processing of

flight strips to be processed by the ground control position.

The local controller forgot that she had placed SkyWest Flight 5569 into position for

takeoff at RWY24L intersection 45 because of her preoccupation with another

airplane.

The local controller’s incorrect perception of the traffic situation that went

undetected because she had an apparent match between her view of the traffic

situation on the airport and the flight progress strip at her operation position.

Misplaced flight progress strips, leading to the development of a false perception of

current aircraft position.

Lack of utilizing the available Airport Surface Detection Equipment radar by the

local controller; however it probably would not have prevented the accident.

These conclusions firmly emphasize the lapse of situational awareness that overcame the

local controller’s mental perception. Workload management played a very key part,

especially in reference to the lack of proper flight strip management within the LAX ATCT.

While the flight crews certainly needed to have maintained a better level of awareness in

regards to their independent place in the operational environment, the final protective

measure against a runway incursion was the local controller who should have maintained a

better mental perception of the environment thereby protecting all traffic involved.


References

AAR-91/08. (1991). Runway collision of USAir Flight 1493 and SkyWest Flight 5569. Aviation

Accident Report-91/08. National Transportation Safety Board. Washington, D.C.

case study- loss of situational awareness

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