Delta Flight 191: Case Study “Microburst”
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Delta Flight 191: Case Study “Microburst”
Carlos G. Mendez
AVIA 340: Aviation Weather
Delta Flight 191: Case Study “Microburst”
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Abstract
This case study investigates the cause of the accident of Delta flight 191 on August 2nd,
1985. The flight which was scheduled to fly from Fort Lauderdale Florida to Los Angeles
California with a layover in Dallas Texas. The dispatch package notified the pilots of isolated
thunderstorms near the airport location. As they reached Texas, they altered their course twice
for developing weather and lined up for an ILS approach into runway 17L. Due to lack of
training and procedure as well as knowledge of microbursts, the flight crew decided to continue
to descend into a cumulonimbus cloud that had shown visible lightning. The flight then
experienced the effects of a microburst leading to the impact of a car, light poles, and water
tanks, this accident took the lives of one hundred and thirty-five people. The NTSB concluded
that the accident was due to pilot error for continuing their approach in a thunderstorm that had
shown visible lightning. They recommended better training and procedures for low-level
windshear training, development of radars that could detect any type of LLWS to be equipped in
airports as well as a version of it to be installed on aircrafts. This accident changed the course of
the aviation industry by sparking the advancement of equipment, policies, and training. This
advancement has made the aviation industry safer by near extinction of aircraft accident due to
microbursts. As recorded the last accident recorded due to a microburst being in 1997 by US Air
Flight 1016.
Keywords: Delta Flight 191, Low-level windshear, Microburst,
Delta Flight 191: Case Study “Microburst”
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Delta Flight 191: Case Study “Microburst”
Introduction
On August 2, 1985, near the Dallas/Fort Worth International Airport at around 6:05 PM
central time, the weather was less than ideal, and Delta Air Lines Flight 191 unfortunately
succumbed to the weather. The flight was a normal scheduled flight from Fort Lauderdale,
Florida to Los Angeles, California with its en route stop as Dallas Texas where the accident
unfolds. The weather brief the pilots had mentioned that isolated thunderstorms were expected in
the area. Due to deteriorating weather they chose to divert their route to a more northern route.
As they began their Instrument Landing System (ILS) approach the co-pilot who was the pilot
flying noticed lightning coming from the cell ahead of them. As they reached approximately
1,000 feet above the Decision Altitude (DA) they encountered a severe low-level windshear
(LLWS) associated with thunderstorms that are known as microbursts. As The New York Times
explains it, “On the final approach, the storm suddenly intensified. As the crew fought against a
phenomenon they never knew existed, the Lockheed L-1011 bounced through the air and
slammed down far short of the runway. It hit a car on a highway, bounced across a field and
rammed into an airport storage tank.” (Phillips, 2005) Even though this was not the first accident
caused by a microburst, as seen with Pan American flight 759 on July 9th, 1982, During this time
pilots did not really know what a microburst was or how to counteract it. This accident took the
lives of 134 people in the plane and the driver of the car that was struck by the plane as it
uncontrollably descended. As we continue to dive into this case study report we will address the
cause of the loss of controlled in more details, the result of the NTSB report, an analysis of the
information gathered, and a conclusion amongst other, in hopes that we could learn more about
this phenomenon and prevent them from taking any more lives as it already has.
Delta Flight 191: Case Study “Microburst”
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Synopsis of Incident
"Later that evening, some of the other employees and I went to the crash site to
volunteer," he wrote. "I was only 19 at the time, and I remember thinking that hell had ripped
open and was right in front of me." (WFAA Staff, 2022) This is but one person that saw the
accident of Delta Flight 191 on August 2, 1985. The accident involving a Lockheed L-1011
Tristar remains to be one of the most devastating accidents in American soil. The flight was
scheduled to fly a normally planned route from Fort Lauderdale-Hollywood International Airport
enroute to Dallas/Fort Worth International airport. According to the dispatch package it
mentioned that, “an area of isolated thunderstorm is expected over Oklahoma and northern and
northeastern Texas.” (NTSB, 1986) The flight for the first half of the flight was calm and
uneventful, until they reached the state line of Louisiana and Texas.
As they began to fly into Texas, they elected to change their route since they wanted to
avoid developing weather on their original route. As the flight crew were being radar vectored by
Fort Worth Air Route Traffic Control Center (ARTCC) the captain noticed a weather cell and
requested to go around it which the controller approved. As They continued down the Standard
Terminal Arrival or STAR, they received a message notifying them of a rain shower they
described as little just north of the airport.
They continued their descent and approach behind American Airline Flight 351 and a
Learjet Model 25 For the ILS runway 17 left. The first officer, who is also the pilot flying,
mentioned he saw lightning coming out of the cell ahead of them. They decided to continue
probably since the smaller Learjet was able to make it made them believe they could do it as
well. The captain called out the altitude at 1,000 feet, at this moment is when they experienced
the microburst which caused the loss of control, The Captain who seemed to have had some
Delta Flight 191: Case Study “Microburst”
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experience dealing with this type of low-level windshear, lets the first officer know to watch his
airspeed. Immediately after he warned the first officer that he was gone to lose it (Airspeed) all
of a sudden to what he then told the first officer to push it (Throttle) up. The Ground Proximity
Warning System (GPWS) alerted the crew to which the captain commanded to press the TOGA
(Take off/ Go Around); however, this was not enough as it was at this moment when the tragedy
happened.
As the first officer lost control of the aircraft, one of the plane’s engine struck a car
killing the driver. It continued to hit a light pole, the ground with the left wing, rotated
counterclockwise, struck a water tank with the cockpit area, caused a large explosion, and the
empennage and fuselage separated themselves. One hundred and thirty-four people aboard the
airplane lost their lives that day. Fortunately, 27 passengers were only injured, and 2 very lucky
passengers were able to walk out of the accident unharmed.
Causation
Unfortunately, during this time not much was known about microbursts. According to the
New York Time the Federal Aviation Administration or FAA had some blame into the lack of
understanding of this short lived but dangerous weather phenomena, “McCarthy, then a
meteorologist with the National Center for Atmospheric Research in Boulder, Colorado, had
struggled for years to persuade the U.S. Federal Aviation Administration and others that the
phenomenon existed and was a severe threat to aviation, but he met with only marginal success.
In fact, several years before the crash of Delta Flight 191, a senior Federal Aviation Agency
official declared McCarthy's theory unbelievable and walked out of his presentation.” (Phillips,
2005) The primary reason for the accident was the lack of understanding of the storm by the
pilots and air traffic control (ATC). If microburst would have been well known and both the
Delta Flight 191: Case Study “Microburst”
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flight crew as well as ATC would have understood the severity of it, they would have most likely
diverted to their alternate airport in San Antonio Texas. This is known to be true as now we have
a very well understanding of this phenomenon and it is shown by the last American microburst
accident being USAir Flight 1016 in 1997. Following a lengthy investigation into the crash, the
National Transportation Safety Board (NTSB) determined that pilot error was to blame” (Finlay,
2022) They blamed it on pilot error because the pilots observed, more specifically the first
officer, the cumulonimbus cloud having visible lightning and decided to continue with the
attempt to land. This with the lack of training and procedures on how to escape or avoid low-
level wind shear resulted in Delta Flight 191 encountering the strong wind shear that microburst
produces so close to the ground.
Decision Criteria
One of the most difficult tasks of the NTSB when conducting an investigation and
writing the report is to write the conclusion which gives the probable cause for the accidents.
There were many findings throughout this investigation, some of these findings were:
In 8 minutes, the cell “D” went from a VIP level 1 to a VIP level 4.
The thunderstorm produced a microburst just north of the DFW airport.
Flight 191 entered the microburst from the south side.
Several flight crews saw lightning and did not report it to ATC.
The flight crew had enough information to include the observed lightning to make
the determination of there being a thunderstorm ahead.
The company lacked guidance and parameter of execution of a missed approach
during low-level windshear.
Delta Flight 191: Case Study “Microburst”
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These findings led to the conclusion of pilot error was the reason for the accident. “The
flight crew's decision to initiate and continue the approach into a cumulonimbus cloud which
they observed to contain visible lightning; the lack of specific guidelines, procedures, and
training for avoiding and escaping from low-level wind shear; and the lack of definitive, real-
time wind shear hazard information. This resulted in the aircraft's encounter at low altitude with
a microburst-induced, severe wind shear from a rapidly developing thunderstorm located on the
final approach course." (NTSB, 1986) There were 4 accidents from 1973 to 1985 that were
caused by this type of low-level windshear, to which the NTSB gave recommendations to the
FAA that they did not implement fully until after this accident. Therefore, this accident could
have been prevented if the FAA would have made mandatory the low-level windshear training to
all pilots and would have invested time and studied the dangers of a microburst fully.
.
Analysis
Delta Flight 191 is one of the most tragic events in aviation history, a journey that ended
with the lives of 137 people. The first cause is due to human factors such as decision-making
skills under pressure, and cognitive biases. The flight crew may have had a desire known in the
aviation world as “get-there-itis,” which according to AOPA is, “The determination to reach a
destination, combined with hazardous weather, claims the lives of dozens of pilots and their
passengers yearly.” (AOPA, 2003) This type of thinking may have led them to underestimate the
weather ahead after all the smaller Learjet was able to successfully.
Another reason that led to the unfortunate event on August 2nd,1985, was the lack of
training, guidelines, and policy from the company to the pilots. “One key finding reported in the
NTSB’s Aviation Accident Report is that the pilots’ wind shear training seemed to prioritize
Delta Flight 191: Case Study “Microburst”
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returning to the glide slope rather than escaping the wind shear completely, thus leading them to
take actions that were “not optimal for ensuring the survival of the airplane.” (Rodgers, 2024)
this is seen in this accident as they incredibly were able to maintain glideslope until the very end.
If when they felt the initial head wind, they would have initiated a climb and added full thrust, as
well canceled that approach immediately, they may have had a higher chance of surviving the
effects of the microburst.
The reason all of the above is even a subject is due to the true cause of the accident the
microburst. They are associated with the mature stage of the thunderstorm. According to an
article on simpleflying.com they state that, “During this stage, the water droplets in the cloud
combine until their weight can no longer be supported and drops in the form of precipitation. The
precipitation can be either rain or hail. The falling of precipitation creates very strong
downdrafts, causing cold air to come down with the rain. Although it starts off as warm air, the
evaporation of some rain and absorption of the latent heat cools the air and makes it denser,
forcing it to fall at a faster rate. As this dense cold air falls at rates of about 1,000 to sometimes
6,000 ft/min it meets the ground and spreads. When it is spread over a small area of about 4-5
km, a microburst is formed.” (Maaz, 2022) A microburst is shaped in the form of a cone;
however, from a pilot’s perspective it is composed of three sides. The initial side which is
characterized by strong headwinds increasing aircraft performance. The middle section, which is
characterized by severe downdrafts, is possibly the worst part of the microburst as it can push an
aircraft down at speeds of 6,000 ft per minute. And lastly, the back end which has strong
tailwind. This is now known thanks to the research done after this incident.
Delta Flight 191: Case Study “Microburst”
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Implications
Many of the reasons that the Delta Flight 191 accident occurred were due to lack of
knowledge. As mentioned, many times above pilots at the time did not know of the existence or
the danger of microbursts. This lack of knowledge led to multiple flights within a 10-year period
before 1985 to crash due to the low-level wind shear induced by thunderstorms, otherwise
known as microbursts. The lack of investigation and study into the weather led companies to not
establish proper procedures, and training in the avoidance and counteraction of microbursts.
Instead, as mentioned above they prioritized the landing and wanted flight crews to maintain
glideslope (vertical navigation guidance). It also maintained a form of complacency in the
evolution of technological advancement, as not much advancement had been made to the radars
to detect these LLWS.
Another issue found in this accident that affects the future of aviation is the improper
crew resource management. The copilot saw a lightning strike from the cell that produced the
microburst before they even entered it. He did the correct thing in communicating it to the
captain but neither did the captain the copilot nor the engineer made a determination on to avoid
the cell, cancel the approach, and either go to a hold and re attempt or divert to their alternate
airport. Instead, there was just an awkward silence between the flight crew after the comment
and the flight continued as if the lightning strikes never happened. This complete disregard for
safety led to them encountering the microburst that ended with their lives as well as that of a
hundred and thirty-three other people. If further investigation that led to a series of
recommendations would not have been conducted there would have been more than 1 accident
due to microburst after this one in American soil. Fortunately, this is not the case and the last
microburst accident following this one in American soil was in 1997 by US Air Flight 1016.
Delta Flight 191: Case Study “Microburst”
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Recommendations
The NTSB had been recommending improvements on the training given to pilots on low
level windshear, safety protocols surrounding these weather hazards, as well as windshear
detection radar utilized by airports to help prevent these accidents. However, the FAA and others
had brushed these to the side and paid little to no attention to them until this accident. Some of
the recommendations given by the NTSB were:
Better wind shear forecasting, that can define the conditions that might be
conducive to microburst.
Improve communication between all mediums so that pilots can receive the most
up to date and accurate information on weather.
Expedite the development of the microwave Doppler radar to be used at airports.
Pilot training on the avoidance of wind shear.
These are only but some of the recommendations from the NTSB that the FAA began to
implement. Another very important recommendation was the development of airborne detection
radar that allows pilot to get real live information or close to it on the aircraft without the need
for ATC. This allows pilots to have the information needed in their disposal at any time without
the need to wait for a opening to be able to ask ATC on locations or times where ATC may be
highly overloaded with work. “Unlike the crew of Delta flight 191, flight crew today are
provided with weather radar systems that can detect possible wind shear zones. This technology
uses the Doppler shift principle, whereby it detects the movement of air mass. If the droplets in
the air mass are moving towards the aircraft, the reflected waves are compressed which increases
the frequency of the return. Higher frequency returns mean there is an increase in the speed of air
mass movement and this is detected as wind shear. As microbursts are associated with strong
Delta Flight 191: Case Study “Microburst”
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wind shear, this system can be used to avoid one.” These implementations have led to the
safeness of the aviation industry today.
Personal Narrative
Delta flight 191 was the very first flight accident that I learned from in detail during my
private pilot training. I was quickly made aware of microbursts and the dangers associated with
them. My instructor taught me to respect weather as it is ever changing and never the same
twice. Thunderstorms are a great example of never being the same, there are many hazards
associated with them however, not all thunderstorms give out all the hazards. according to AC
00-24 Thunderstorms published by the FAA some hazards associated with thunderstorms are
tornadoes, turbulence, microburst, icing, hail, low ceiling, visibility, and lightning. However, not
all thunderstorms develop tornadoes or microbursts. In order to mitigate the possibility of this
and other occurrences to happen to me in my journey in live I plan to continue my education on
resource management, problem-solving skills development, knowledge on different as well as
any newly published weather phenomena. This will help me not only learn about the hazards that
mother nature brings, but it will help me avoid them and allow me to have better decision-
making skills under high stress and pressure, like when flying towards deteriorating weather. I
also plan on learning about my current and future aircrafts equipment as I progress through my
journey so that I can be able to interpret the message that the images may be giving me. This is
because the aviation industry may advance technologically and may have state-of-the-art
equipment but if the pilot does not know or understand what the equipment is showing them it is
as if the equipment is not on the aircraft. Delta Flight 191 shows me the importance of respecting
weather, and not falling into the hazardous attitudes like “get-there-itis,” this mentality made the
pilots continue the approach into a known fully developed thunderstorm when the officer saw the
Delta Flight 191: Case Study “Microburst”
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lightning and should had been an indication of a diversion. I will live by the mantra of rather be
safe than sorry.
Conclusion
The unfortunate events of Delta Flight 191 serve as an example of why weather and
recommendations should be taken seriously. During this case study report it was mentioned how
the FAA did not believe in the possibility of a microburst existing, how companies lacked the
procedures and protocols to correctly avoid or counteract low-level windshear. Microbursts,
which are considered the most dangerous wind shear a pilot can face, are short lived and cover a
small area of around 2.3 km. After the accident surrounding Delta Flight 191, the FAA and
airlines company placed much emphasis on developing training, procedure, and technology to
mitigate and prevent accidents like this one from reoccurring. It is unfortunate that they waited
until this accident to really place emphasis on this phenomenon given the recency of other
accidents involving this type of windshear. However, fortunately after the implementation of the
recommendation given by the NTSB according to a report from the National Weather Service
only one other accident has been recorded where microburst was to blame, this is attributed to
US Air Flight 1016 which occurred on July 2nd, 1994, in Charlotte, North Carolina. This shows
that the study of microbursts, implementation of company’s policies and guidelines on the
detection and avoidance of microbursts, the training, and the equipment development have
greatly mitigated the risk of entering a microburst.
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References
AOPA. (2003, September 26). Get-there-itis. AOPA.
https://www.aopa.org/training-and-safety/air-safety-institute/accident-analysis/featured-
accidents/epilot-asf-accident-reports-get-there-itis
FAA. (2013, February 19). AC 00-24C - thunderstorms - federal aviation administration. FAA.
https://www.faa.gov/documentlibrary/media/advisory_circular/ac%2000-24c.pdf
Finlay, M. (2022, August 2). 37 years ago today: The crash of delta air lines flight 191. Simple
Flying. https://simpleflying.com/delta-air-lines-flight-191-anniversary/
Maaz, A. (2022, July 8). Microbursts - the most dangerous wind shear a pilot can face. Simple
Flying. https://simpleflying.com/microburst-pilot-wind-shear/
NTSB. (1986, August 15). Accident report Delta Flight 191. NTSB Report.
https://www.ntsb.gov/investigations/AccidentReports/Reports/AAR8605.pdf
Phillips, D. (2005, August 1). How a “microburst” downed a jetliner and revolutionized flight
safety. The New York Times. https://www.nytimes.com/2005/08/01/world/americas/how-
a-microburst-downed-a-jetliner-and-revolutionized-flight.html
Rodgers, C. (2024, April 24). Deadly microburst: The tragic story of delta air lines flight 191.
Simple Flying. https://simpleflying.com/delta-air-lines-flight-191-history/
US Department of Commerce, N. (2020, October 2). Delta Flight 191 incident at DFW Airport.
Delta Flight 191 Incident at DFW Airport. https://www.weather.gov/fwd/delta191
WFAA. (2022, August 2). Delta 191 plane crash at DFW Airport: When “hell ripped open” |
wfaa.com. WFAA. https://www.wfaa.com/article/news/local/delta-191-plane-crash-at-dfw-
airport-1985-dallas-fort-worth-airline-crashes/287-4649be59-bab7-4d52-b903-
3a7236834c82
