Ergonomics and human error in the USAir 1493 and SkyWest 5569 collision

Improper Ergonomics caused USAir 1493 and SkyWest 5569 Accident

Accident Investigation: Improper Ergonomics was the Cause

Ergonomics was derived from two Greek words: ergon which means work, nomoi, on the hand means natural laws, in creating a word with the meaning, the science of work and an individual's relationship to that work. Another related definition according to International Ergonomics Association describe Ergonomics as the scientific discipline that deals with the understanding of interactions among humans and other elements of a system, as well as the profession that applies principles, theory, methods and data in designing as an attempt to optimize human well-being and overall system performance. Improper Ergonomics in the airport always cause a number of accident and fatalities that otherwise would have been avoided if the handling was done procedural considering the rules in addition to up-to-date facilities.

Introduction

On the day of the flight accident Friday, February 1, 1991 USAir Flight 1493 (United States domestic passenger flight) was schedule to fly from Syracuse Hancock International Airport in New York to San Francisco International Airport in California. It was to pass via Washington, D.C., Columbus, Ohio, and then Los Angeles in California. The features of LAX airline as its destination included four parallel runways, and associated taxiways north of the terminal known as North Complex. Any aircraft that would land on the outer runway-24R- had to cross the inboard runway-24L- for it to reach the terminal. Investigation pointed out several irregularities that happened on this day of the accident and commonly narrowed down to human handling or improper ergonomics. Even though facilities at the LAX airline were somehow not to the required standards, its correct use and up-to-date maintenance that was ignored even after it was pointed out, could have not warrantee such a big loss of lives that was realized in this incident.

One of the flight involved SkyWest Airlines flight 5569, which is a twin-engine Fairchild Metroliner meant to fly to Palmdale California having 10 passengers and two members of crew on board. It was cleared to taxi to Runway 24L by Air Traffic Controller in the LAX tower. It was to move from gate 32 towards the runway passing through taxiways Kilo, 48, Tango, and 45, (Carroll, James., 1991). However, the plane was not clearly visible from the tower on taxiway 48 between Tango and Kilo within the area referred to as "no man's land." The flight was logged about 8,800 hours of total flight time as well as accruing about 8,000 hours of total flight time from Prentice.

Before the Accident

Just before SkyWest 5569 reached runway 24L, already a Wings West aircraft had landed on 24R as it waited to be granted permission of crossing 24L and taxi towards the terminal. While the local controller tried crossing the Wings West aircraft, the crew had already altered frequencies and failed to answer, thereby distracting the local controller in the event of trying to re-establish communications. Before long past 6 PM local time, USAir 1493 was already making its final approach to LAX, and at the same time SkyWest 5569 had been cleared by the local controller to taxi where it was to takeoff on 24L at the point of taxiway 45 intersections, which is 2,200 feet (670m) up away from the runway threshold. There were four attempts by the local controller before the Wings West aircraft controller responded to the tower followed by an apology of switching frequencies; which has already caused some distraction, (Stu Beitler, 2011). Afterwards US1493 was cleared to land on 24L by the local controller, at the same time SkyWest 5569 was on hold on the runway ready for take off.

As these activities were going on, a Metroliner Wings West aircraft same as SkyWest 5569 communicated to the tower informing that they were ready for takeoff. This same local controller queried the aircraft regarding their position, and she was told that they were on hold on a taxiway short of 24L. Another distraction is experienced again because the flight progress strip for this flight was not yet given by clearance delivery controller to the local controller while the local controller had mistakenly confused this taxiway Metroliner with SkyWest 5569 assuming the runway to be clear of aircraft. USAir 1493 first officer could recall this conversation, but in the conversation there was no aircraft cleared to hold on the runway.

Immediately USAir 1493 touched down a short distance from the runway threshold, the first officer realized that SkyWest 5569 was on the runway and in panic decided to apply maximum braking. Within no minutes USAir 1493 had slammed into SkyWest 5569 both skidding down the runway resulting to Metroliner crushing beneath the 737's fuselage. This aircraft veered off to the left of the runway settling on the far side of the taxiway catching fire around a closed fire station building, (Steve Springer, 1991). Various huge remains from the Metrolinear such as the right engine, wings, and tail among others could be seen at the runway and within abandoned fire station. Among those who witnessed the accident were individuals from a plane having on board Vancouver Canucks as they arrived for a NHL hockey game against the Los Angeles Kings. The charter aircraft's captain had to power up the engines to move away from the fireball of the accident since they were not sure if the USAir 737 was going to stop without reaching them, (Tailstrike (n.d.)(2010).

Results of the Accident

Among the 34 who perished were 12 people from SkyWest 5569 (10 passengers and 2 crew who were First Officer Frank C. Prentice III and Captain Andrew J. Lucas, while USAir 1493 lost 22 of its 89 members on board (20 passengers and 2 crew members; flight attendant Deanna Bethea-Kearney and Captain Collin Shaw). The death of Captain Shaw was as a result of the aircraft hitting the abandoned station from the nose, crushing cockpit section where the seat of the captain was situated. USAir 1493 had also 11 passengers and 2 crew members who sustained serious injuries, 15 passengers and 2 crew members sustained minor injuries while 37 were not injured, (Eben Harrell, 2009).

Several fatalities from USAir 1493 happened majorly were the passengers who sat in the front of the plane, a place where the post crash fire from forward cargo hold, facilitated by a mixture of fuel from the crushed SkyWest 5569 and gaseous oxygen which originated from the 737's damage crew system of oxygen. All the passengers who were seated in row 6 and forward either perished or sustained major injuries, yet all passengers of row 17 escaped though some sustained minor injuries.

One crew member and 2 passengers were the only people who escaped using the forward service (RI) door; the main cabin (L1) door could be operated as it was damaged. The left over-wing exit was used by only 2 passengers just before the intensity of the fire increased. Many of the survivors managed to escape through the right over-wing exit, while the rest of cabin occupants who survived escaped via the rear service (R2) door. Though the rear passenger (L2) door was opened for sometimes it was closed immediately because of the spreading fire towards that side of the aircraft. Among the events that slowed down the evacuation from the right over-wing door were: some of the passengers seated in the exit row were not able to open the door, seat back of the exit window seat was folded forward obstructing partially the exit, and a brief scuffle between two men at the exit.

There were only two bodies found in their seats from USAir, while according to the authorities, 17 managed to unbuckled their seat belts but succumb from smoke inhalation as their tried to reach the exits. James Burnett, the head of National Transportation Safety Board (NTSB) investigation team confirms that he could not think of a current accident where majority of people are up and out of there seat but do not make it out. Death of one person who evacuated USAir 1493 was reported to be as a result of thermal burns some days after the accident. Though never listed as part of USAir 1493 fatality because of language in the Code of Federal Regulations (49CFR830.2), one among the 13 seriously injured passengers unfortunately succumbed to various traumatic injuries 31 days after the crash. According to the regulation fatality takes place within 30 days of the accident there it was not included.

Aircraft Emergency Exits

After the study of Type III exits by FAA and the way size had impacted the evacuation before LAX accident, and considering the USA1493 passengers who died following smoke inhalation as they waited to exit, facilitated the need to change the rules to 14 CFR 25.813. On April 9, 1991 the notice was issued for public rule-making (NPRM) to improve access of Type III exits which was done and by June 1992 the final rule was affected.

Airport Surface Detection

Apart from changes in regulation and policy, technology at LAX has also improved the radar systems used in controlling air traffic ground operations. During the accident the Airport Surface Detection Equipment (ASDE) radar system in use was meant to monitor ground traffic activity, particularly at night. When air traffic personnel monitor airplane takeoffs and landing visually adds additional protection in reducing the risks of runway incursion. For example, when an aircraft taxi into position to hold within the runway intersections and the tower controller is not able to see them poses a threat to the safe airport operations (Malnic, Eric & Connell, Rich., 1991). At the moment of accident the local controller cleared an aircraft to depart from the middle of runway in the night but she did not have direct visual monitoring capability,

Due to this, FAA Air Traffic Services came up with a procedural changes just after the accident via a general notice (GENOT), indicating that controllers were not allowed to authorize aircraft to taxi into position and hold at an intersection between sunset and sunrise. Aircrafts were also burred from taxi into position and hold at an intersection whenever the tower was not able to see them. Later these procedures were incorporated into FAA Order 7110.65.

When emergency briefings are conducted for passengers seated within the exit rows, it improves the ability to effectively evacuate passengers in case of an accident. Taking this into consideration, FAA came up with new operational rules requiring operators to screen and brief passengers seated within the exit rows. Operators are required by this rule to develop and implement plans for this screening and briefing. Even though USAir had already developed and implement their plan; they have made more improvement to the plan to facilitate more evacuation capability.

After the investigation for the accident found that, except for seat covering and carpeting, the entire cabin furnishing burned. The consideration was that if the cabin furnishings had not allowed fire to spread on it fast with much smoke throughout the cabin might have given passengers more time for evacuation increasing number of survivors. Therefore, it was important to enhance cabin materials flammability standards. The aircrafts had to effect theses changes in the interiors of transport category airplanes using the latest flammability standards and retrofit program for the in-service fleet.

Some of the changes that needed to be undertaken were operating procedures within control towers which provide redundancy to lapse in human performance like always having flight progress strips when coordinating aircraft movement between controller positions. Usually human senses such as hearing and sight together with the memory tend to be the main means by which traffic is controlled and managed by air traffic control tower personnel. They are supported by processes like the use of flight progress strips but when there is only one way to be used, usual distraction might bring a lapse resulting to poor judgment. For example, LAX facility for ground control operations did not require flight progress strip; therefore when the local controller identified that a strip was missing for a specific aircraft, this distraction was never accounted for by a redundant system. The implemented safety system in turn allow for occasional human lapses.

In most occasion supervisors carry out over-shoulder evaluations of controllers in making sure that the needed levels of controller as well as facility performance are maintained. Once any deficiency has been identified then corrective action need to be identified and implemented so that adequate level of safety is maintained. When supervisor carried out evaluation of the LC2 controller, six weeks before the accident discovering five performance deficiencies but no action was taken; and the investigation in LAX on the this accident showed that performance of the controller was related to the existing facility procedures which failed to allow for lapses in judgment as well as decision making; did away with human performance redundancies, (Chris Kilroy, 2013). As a corrective measure LAX went ahead and modified the local and ATC-wide procedures to make sure that redundancies for human performance were in place.

Due to these improper ergonomics Baum Hedlund firm sued the airline and the FAA for negligence arguing that air traffic controller cleared the USAir jet to land and at the same time SkyWest flight had been cleared to taxi on the same runway. In addition the firm charged the FAA with negligence following failure to provide adequate policy direction and supervision to its air traffic control facility manager.

Conclusion

Indeed improper ergonomics was the major cause of the accident, in addition to the inadequate facilities that were in LAX. The captains from the USAir Flight 1493 and SkyWest had little they could do when the accident was taking place because they followed the required instructions from the ground controllers and they followed as were instructed. A little distraction interferes with the level of concentration on the part of the controllers and hence commonly causes accidents that could be avoided. Therefore with the help of new technology even when controllers are distracted there is likelihood for recovery since there are support facilities which assist them to identify if the instruction they are giving is the correct one at a given point. With the recommendations from NTSB and the lesson learnt from the accident that almost occurred later involving Boeing after USAir flight 1493 with the SkyWest collision, LAX has improved their facilities as per the required standards reducing chances of improper ergonomics as the cause of further accidents.