Abstract
The Delta Airlines flight 191 clash is one of the most significant incidences in aviation history. It led to massive changes in how the airlines and the government addresses aviation safety. The concept of microbursts was novel at the time of the clash and the increased research efforts revealed how it affects aircraft and how it can be avoided. DFW and other airports learned critical lessons and used these lessons to implement improved detection system both on the ground and the planes.
Introduction
The aviation industry can be considered to be one of the riskiest industries in the world. There have been multiple accidents since the aircraft was first invented. Commercial flights today are the major concern when discussing the safety of air travel. This is because the incidents that have happened in the history of these businesses have resulted in massive losses of human life. Accidents such as the Delta Airlines flight 191, which occurred on August 2, 1985, killed over 137 people.
At the time it happened, it was the third accident in the United States since 1975 to involve a then-novel concept of microburst and to kill over 100 people. Such an extent also means heavy losses for the airlines illustrating the fact that aviation safety is of utmost interest to all the stakeholders. The Delta Airlines flight 191 clash is argued to have been one of the most significant incidences in the history of aviation safety as it led to a change in how airlines and governments approach aviation safety.
Background
The Delta Airlines flight 191 is one of those accidents to have been caused by a phenomenon known as a microburst. This is a weather condition involving an intense thunderstorm downdraft. The National Weather Service defines a microburst as a small downburst that has an outflow of below two and a half (2.5) miles or 4 kilometers for a horizontal diameter (“Thunderstorm hazards – Damaging wind,” n.d.). Additionally, it tends to last for between two and five minutes. Microbursts may be small in size but they can produce destructive winds reaching up to 168 miles per hour or equivalent to 270 kilometers per hour. They present dangerous conditions for pilots and have been responsible for multiple aviation accidents, including the Delta Airlines flight 191 crash.
The mechanisms and the effects of a microburst have been explained by the National Weather Service, including the sequence of events leading to an incident. Pilots descending into an airport follow an imagery line to the runway called a glide slope. When they enter a microburst the aircraft encounters a condition known as headwind which is an increase in the speed of the wind over an aircraft. The strength of the wind tends to create additional lift which causes the aircraft to rise above the imagery line. Pilots, in an attempt to return the aeroplane to the right position, lower the throttle to reduce the speed of the plane thus causing it to descend.
When the pilot successfully flies through to the other end of the microburst, the direction of the wind changes and becomes a tailwind because it is now behind the plane. The wind over the wind reduces causing the aircraft to sink below the glide slope. It is important to notice that applying full throttle fails to work because the tailwinds stay stronger and the result is crashing on the runway. These events are what happened at the side of the Delta Airlines flight 191. The weather changes from the Stephenville radar shows there must have been strong winds barreled through the north side of the DFW airport (Delta Flight 191 Incident at DFW Airport, n.d.). This was an indication of a microburst and the primary cause of the crash.
In addition to the microburst, it is important to appreciate other aspects of the crash. The history of the aircraft involved in the crash, a Lockheed L-1011 TriStar, was labelled a plane too good to be true. The DC-10 was a tri-jet engine similar to the DC-8 but equipped with cost-saving features. The engineering features of the plane and what made it unique have been explained by Beresnevicius (2018), and some of them may have contributed to the crash. However, most attention has been turned to the role of the weather and maintenance mistakes.
Events
Timeline
The timeline for the Delta Airlines flight 191 crash has been documented through the Stephenville radar imagery. As mentioned earlier on, the microburst was the main reason for the accident meaning the radar imagery documents the weather changes up to the time of the incident. Around 5:00 PM, some convections were observed near the DFW airport which was considered to be remnants of dying thunderstorms in the area. However, the CDT echoes began to intensify and some newer echoes indicated that air was likely being rapidly forced upward along outflow boundaries (“Delta Flight 191 Incident at DFW Airport,” n.d.).
The Delta Airlines flight 191, at this time, continued its flight towards the airport way of the Blue Ridge VOR which was just east of Melissa, TX. By 5:48 PM, the secondary echoes intensified north of the runway 17-left. A black speck or hole in the southern-most cell indicated that the intensity had increased to the “Strong” or the VIP 3 category. The convective activity was visually observable by the Delta Airlines flight 191 crew.
At 6:00, just moments before the crash, the radar imagery indicated that there were two distinct cells adjacent to each other with each recording “strong” intensity. These cells were located between 2 and 7 miles north of the 17l runway which was Delta Airlines flight 191’s intended target. The crash occurred at 6:05: as the aircraft landed just short of the runway and striking a vehicle on Texas State Highway 14 (“Delta Flight 191 Incident at DFW Airport,” n.d.). The plane was emerging from precipitation heavy enough to enshroud it. The eye witness accounts state that the plane struck the vehicle and rebounded and slammed into the ground. A large fireball consumed much of the aircraft with 137 passengers dying as a result.
Response
The emergency services responded to the crash after it took place. The details of the response are described in the 1986 Aircraft Accident Report by the National Transportation Safety Board (1986). All airport emergency and fire units were alerted within the first minute of the accident and, after 45 seconds, three fire trucks from station no. 3 arrived at the incident scene and started fighting the fire. More units were dispatched from stations No. 3 and No. 1 within the following five minutes. The firefighters managed to contain the fire within 10 minutes after the sounding of the alert despite experiencing heavy rains and wind gusts.
The other emergency response teams to be engaged were the medical units from the DPS department who arrived within five minutes of the alert. The emergency medical technicians (EMT) comprised of 16 responders while the paramedics invo0lved were 2. This is in addition to the DPS mobile intensive care unit and medical patrol vehicles. They immediately established triage stations and helped save lives that could have been lost. It was reported that without their efforts over half of those who survived could have succumbed to the accident. The majority of those who survived were those located in the rear smoking section which had broken free from the fuselage before the plane crashed onto the water tanks. These survivors were taken to Parkland Memorial Hospital for further treatment.
Also in response to the crash was the notification of the hospitals near the airport regarding the accident. At 6:25 PM, the operator of the DPS notified John Peter Smith Hospital in Fort Worth. Controversially, there were other hospitals closer to the airport, including North East Community and Hurst-Euless-Bedford hospitals. However, they still received patients injured in the crash even though none of them was notified on the status of the victims or even their intended destinations.
This can be seen as a major problem because the hospitals could have used the information to increase their preparedness. Other failures in crisis response included that the Grapevine, Hurst, and Irvin community centers did not receive specific ambulance requests. Despite this, the ambulance company in Hurst heard the DFW radio crash alert and made a quick response after confirming the incident by telephone with the airport.it was only after the Grapevine fire chief met with fire chief at the airport that ambulances from Grapevine were requested and arrived at the scene at 6:40 PM.
With these response issues emerging, the accident report indicated that the DFW airport emergency plan comprised procedures for ambulance requests. However, the off-airport agencies could not clearly understand the nature of assistance being sought. The accident report also explains that the result of these communication problems included confusions such as fire trucks and units being dispatched when ambulances were expected. The report concludes that even though the response has issues, the airport emergency plan at DFW met the requirements of 14 CFR 139.55. Additionally, the DFW had an FAA certification inspection of the airport and the emergency plan on November 14 to 15 in 1984. The last emergency response drill was also conducted by the DFW in May 1979.
Aftermath
Emergency Response Protocol
Much of the aftermath details are concerned with how the DFW and other airports implemented shear detection systems to detect and avoid microbursts such as the one that caused the crash. Delta Airlines and all other commercial airlines, following the orders from the Federal Aviation Administration, implemented installed on-board wind shear detection systems (Delta Flight 191 Incident at DFW Airport, n.d.). Additionally, many airports across the US installed ground-based wind shear detection and since then the number of incidents caused by microbursts has greatly reduced. There are scant details, however, of how the emergency response protocols changed after the crash. However, the available information indicates that DFW airport made several improvements in rescue efforts.
First, fire suits have been dramatically advanced to allow firefighters into burning structures safely. Second, the updated fire trucks had specialized tools, which could shoot lance-like probes into a burning aircraft. The probe is often called a Snoozle and it is attached to a hose to inject fire retardants into a fuselage. This has the effect of cooling the fuselage to allow rescue workers to save lives inside. Additionally, these trucks have infrared sensors, which are used to detect the hottest parts in a crash. Lastly, the crash notification systems at DFW were improved to include an automatic voice notification system. This new response mechanism helps to significantly reduce the notification times. Improved response times and other developments have been gradual and some have taken place after other major accidents such as the Delta Airlines Flight 1441.
ARFF Crews
There are also scant details regarding how the training if ARFF crew changes. However, there were efforts to increase the number of personnel in this department not just at the DFW but also across the world. The DFW may be considered as one of the busiest airports across the United States and, therefore, increasing the number of trained firefighting personnel is crucial. One of the available accounts of how the training was tweaked is given by fire chief brain McKinney who started training at DFW in 1986. After becoming fire chief in 2003, he changes to the ARFF training. His experiences with the DFW’s fire response units may have helped him envision better response training. However, the details of immediate changes after the Delta Airlines flight 191 have not been included in his account.
One of the better indications of immediate changes is given in an interview with Christopher Gay who worked at the airport as a firefighter for about two decades. In his narration, the Delta Airlines flight 191 was soon followed by the Delta Airlines flight 1441 and these two incidences forced all senior management to become change drivers (Coarsey, 2020). Firstly, the training focused on improving the mental and physical capabilities of the firefighters. Muscle memory was enhanced through the use of visual and audio cues to help the trainees identify risks and rewards and to improve their capability to predict rapidly changing conditions.
The ARRF crew was training was intended to allow the members to operate in the worst possible conditions. Additionally, all response gaps were identified and integrated into the ARFF crew training. Further capabilities were developed, including sending teams being the airport fences. Training methods and techniques were also revolutionized to include tabletop drills, functional exercises, skill-based training, full-scale exercises, skill development, and lectures among others.
ATC Protocol
The disaster preparedness, as detailed in the accident report, was described by the Safety Board as experiencing communication and coordination problems during any large emergency response that involved multiple jurisdictions. At the time of the flight 191 crash, it was 6 years since the last full-scale exercise. These are some of the issues that highlighted the need to revolutionize the ATC Protocols at the DFW airport and in the region as a whole. ATC comprises tasks related to the assessment of weather impacts and managing air traffic sequences among other tasks. Regarding the weather assessment, the DFW increased the efforts to study the implications of microbursts. Before the accident, DFW was part of a Joint Airport Weather Studies (JAWS) that was studying microbursts.
The study had just concluded, but the downside was that it focused only on dry microbursts and not the wet microbursts that ultimately caused the crash. In 1986, a new study named MIcroburst and Severe Thunderstorm (MIST) was initiated to fill this gap in the previous study (Delta Flight 191 Incident at DFW Airport, n.d.). The research from both MIST and JAWS revealed the true dynamics of microbursts which helped explain both the occurrence of the accidents and means of mitigating the disasters through improved detection. The new ATC protocols include the installation of the Terminal Doppler Weather Radars (TDWR) which are a type of radar system strategically placed at high-risk areas. While this may not be the airport’s jurisdiction, the regional ATC and other relevant bodies such as the NWS and DoD are responsible for their maintenance.
Additionally, the Integrated Terminal Weather System (ITWS) have been installed to offer meteorological support to airports and planes. The ITWS functions by combining the data from surface weather observation stations, TDWR, and other equipment both on the ground and on the aircraft.
Bad Weather’s Influence on Crashed
The Delta Airlines flight 191 and similar crashes have helped to illustrate the influence of bad weather on aviation. According to Gultepe et al. (2019), multiple research explorations have revealed that weather can have severe impacts on both defense and commercial aviation operations. This knowledge has existed since the 1900s when it emerged that aviators would increasingly need the meteorologists to predict the fog and wind and to direct routes with fewer clouds.
The elements of weather that have been known to cause major accidents include carburetor icing, wind, high-density altitude, thunderstorms, thermal lift, shear, extreme temperature, downdrafts and updrafts, turbulence, visibility or veiling, precipitation, and storms. The Delta Airline flight 191 crash is the perfect example, in this case, to show how bad weather affects aircraft. Microburst at the time of the accident may have been a novel concept but its study has helped provide a great understanding of the basic weather patterns in both wet and dry conditions that are likely to affect airline operations.
In addition to causing accidents, weather can have also been responsible for several types of damages for both the aircraft and other airline equipment and facilities. In the Delta Airlines flight 191 crash, the damage of the incident extended to water tanks and the vehicle onto which the plane crashed. In strong winds, the aircraft may finally land without causing accidents but such conditions have been known to damage landing gears and other parts of a plane. There are also huge financial losses for aviation from accidents resulting from bad weather. For example, three-day freezing in the UK caused losses worth over USD 50 million for businesses (Gultepe, Sharman, Williams, & Zhou, 2019). Weather causes flight delays which in turn reduce the operational efficiency of businesses including those remotely related to aviation.
Conclusion
This paper supports the thesis that the Delta Airlines flight 191 clash it led to a change in how airlines and governments approach aviation safety. The incident killed over 137 people and was caused by a phenomenon called a microburst. This condition has been studied by the DFW jointly with other airports and has helped implement new ATC protocols and equipment intended to improve detection.
The timeline and response for the crash have been outlined alongside an account of the aftermath. In these sections, it has been established that the DFW may have adhered to aviation safety but some gaps needed to be addressed immediately. An account of how the training of the ARFF crew evolved ads to the observation that the Delta Airlines flight 191 crash is among those that significantly influenced how aviators approach aviation safety.
References
Beresnevicius, R. (2018). Lockheed L-1011. The plane that was too good to be true. Aerotime. Web.
Coarsey, C. (2020). Healing a memory. Family Assistance Foundation. Web.
Delta Flight 191 Incident at DFW Airport. (n.d.). Web.
Gultepe, I., Sharman, R., Williams, P., & Zhou, B. (2019). A review of high impact weather for aviation meteorology. Pure and Applied Geophysics, 176(5), 1869-1921. Web.
National Transportation Safety Board. (1986). Aircraft Accident Report, Delta Air Lines, Inc., Lockheed L-1011-385-1, N726DA, Dallas/Fort Worth International Airport, Texas, August 2, 1985. Washington, DC.: National Transportation Safety Board.
Thunderstorm hazards – Damaging wind. (n.d.). Web.