Case Study Flight 1248 1
Case Study Flight 1248
Cale Schueler
AVIA340_D04_202340
Case Study Flight 1248 2
The Case Study of Flight 1248
On December 8th, 2005 a 737-7H4 Southwest Airlines flight 1248 landing at Chicago
Midway International Airport overran the departure end of runway 31 center. The flight landed in
a snowstorm which was one of the main reasons why the aircraft was not able to stop. There was
one fatality in a car that the aircraft struck but no one else was killed which was very fortunate
considering the incident could have been much more deadly.
The Southwest 1248 flight had departed from Baltimore with a plan to stop at Chicago
Midway and Salt Lake City before reaching its final destination of Las Vegas McCarran Airport.
The aircraft was a brand new 737 piloted by Captain Bruce Sutherland and First Officer Steven
Oliver. Captain Sutherland had over 15,000 flight hours and the First Officer Steven Oliver had
8,500 total flight hours, 4,000 of them for SouthWest in the Boeing 737. So both pilots were
seasoned, experienced pilots with lots of training and hours. Neither had been in an incident
before the incident at Chicago Midway.
Southwest Flight 1248 was intended to leave Baltimore at 14:55 or 2:55 p.m. but due to
weather was not able to depart until 16:50 or 4:50 p.m. The weather as they approached Chicago
was also not good, with low visibility, and precipitation, in this case, snow and ice. Another issue
that contributed to the incident was the introduction of new technology on the aircraft. Auto
brakes had been added to the Boeing 737-700 and pilots at the time had received very little
training on how to use them effectively. While the pilots tried to use the new autobrakes properly
they forgot to initiate the reverse thrusters in time and by the time they realized it and activated
the reverse thrusters it was too late and the aircraft. Both pilots tried to apply manual brakes but
it was not enough and the 737 went off the runway, through perimeter fences, crashing into
several cars.
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To understand more about what happened on December 8th, 2005 there are many
more details that need to be covered to understand what exactly went wrong and why. A synopsis
of this incident should help bring to light all of the mistakes that led to the accident in Chicago
Midway. An analogy often used in the aviation world regarding incidents, accidents, or anything
in between is most commonly known as the Swiss cheese model. This is defined as “The Swiss
Cheese Model provides a practical framework for visualizing how multiple threats can combine
to create a dangerous situation. By being proactive and vigilant, pilots can reduce the likelihood
of accidents and ensure safe flying for themselves and their passengers'' (Mead, 2023, para. 8).
We will be looking at multiple threats that created the dangerous situations for Southwest Flight
1248 and how they combined to create a serious incident.
The crew of the Boeing 737-700 of flight 1248 had been holding in the air for a while
waiting to land as the airport was clearing off the runway environment so that planes could land.
The only runway availabe was the 31C runway; an issue with the runway is that there was a
tailwind. Another threat to the flight that had remained was the poor visibility at Chicago
Midway. But as the airport finished clearing snow off the runways, flight 1248 was vectored for
an approach to land at 1900 hours. The plane touched down and went off the runway before
continuing off the runway crashing through fences and automobiles. During the incident, there
were Instrument Meteorological conditions that were an additional complication and threat to the
flight. After the aircraft had come to a stop it was severely damaged. The NTSB provides some
key flight recordings that help understand what exactly happened on touchdown all the way
through to the crash. The first interesting flight recording is that when the plane landed it had a
ground speed of 131 knots, 6 seconds after touchdown the auto brakes reached peak pressure
commanded by the auto brakes only slowing the aircraft down to 113 knots and the auto brakes
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were not switched off for another 6 seconds. We also see how long it took to activate the thrust
reversers according to the NTSB flight recordings, “The first indication of thrust reverse activity
occurred 15-seconds after main gear touchdown. The thrust reversers were fully deployed 18-
seconds after touchdown, and N1 reached 80% 9-seconds later or 27-seconds after touchdown as
ground speed decreased to 62 knots”(Grossi, 2006, p.2). Thirty-three seconds after main gear
touchdown the Boeing 737 departed the paved surface. Eight seconds after exiting the runway
surface the aircraft came to a stop.
The cause of this incident was determined by the NTSB to be a failure by the pilots to
perform the correct procedures. “The National Transportation Safety Board determines that the
probable cause of this accident was the pilot’s failure to use available reverse thrust in a timely
manner to safely slow or stop the airplane after landing, which resulted in a runway overrun.
This failure occurred because the pilots’ first experience and lack of familiarity with the
airplane’s auto brake system distracted them from thrust reverser usage during the challenging
landing”(Aircraft Accident Report, 2007). But the NTSB also referred to the fact that pilots
failed to divert to alternate due to the safety conditions from both the weather paired with the
new braking system. Since a large portion of this accident was affected by weather it is important
to look at the development of the conditions during this flight and learn to recognize similar
weather for other pilots to be aware of upon approaches. The meteorology portion of the NTSB
report states that the snowstorm that Southwest Flight 1248 encountered began in the early
afternoon. There were 3-6 inches of snow that extended up from Midway International into
northern Will County and over 11 inches of snow was recorded. The most alarming part of the
weather report is that the most intense snowfall was from 5-6 pm just an hour before flight 1248
would begin its vectored approach. This intense precipitation was the leading weather-related
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cause of the incident, it made for difficult IMC conditions and a contaminated runway upon
touchdown. The combination of intense precipitation in the form of snow and an unfamiliar new
braking system is what led to the aircraft sliding off the runway and into several automobiles.
NTSB's final weather meteorological conclusion is that “The case of December 8, 2005, was
notable in that the enhanced banding occurred over a major airport and was a contributing factor
in a fatal aircraft incident by Southwest Airlines. Intense snowfall of up to 3 inches per hour in a
period of about 1 hour prior to the incident may have impacted the ability of the airport to
maintain runway composure”(Meteorology 5, 2006).
The decision of the pilots of Southwest Flight 1248 was not to divert or continue to hold
but to try an approach to land on runway 31C. Looking at the results of this incident it is clear
that the pilots of Flight 1248 made an unsafe and unwise decision regarding the safety of the
flight and its passengers. These pilots were very experienced and well trained but they put
themselves and the passengers in danger by risking landing in unsafe conditions. Another
important thing to take away from the course and apply to this incident is knowing when to go to
plan B. For airlines, they are very capable of making it to many other airports if the weather does
not look safe. When there is heavy snow, a tailwind for the only available runway, and low
ceiling Instrument meteorological conditions, they should have opted to divert to their plan B.
The result of their decision did end up taking the life of a child and they were fortunate that no
other passengers were harmed when the aircraft departed from the runway environment. Many
more lives could have been lost which is why the FAA made changes to help prevent any more
unsafe runway accidents/incidents. The determined causation was that the pilots failed to activate
reverse thrusters in time because they were distracted by the new auto brakes that were added to
the Boeing 737-700. But this also fell on Southwest Airlines for not properly training their new
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pilots on the new auto brakes that were implemented while there was also no margin of safety to
use the new auto brakes. Lastly, as mentioned before, the failure to divert is one of the most
important takeaways that has been taught from this course. If conditions are unsafe while you are
uncomfortable with a new system within your aircraft, divert where it is safer.
After determining the decisions that were made during this flight it is important to
analyze them. Analyze the causes, any observations, and any findings that would contribute to
how this routine flight from Baltimore to Chicago became such an important milestone in
aviation safety. One observation worth looking into was with the thrust reversers, it is known that
the pilots were late to activate them but how late and how badly they were needed. With
contaminated runways, it seems it is very important for pilots to implement thrust reversers very
quickly. “Once main gear touchdown has occurred, full lift spoiler deployment should be
ensured, de-rotation should start and thrust reverser deployment should occur. These actions will
increase wheel loading, which will ensure the achievement and/or continuation of wheel
rotational speeds sufficient to allow effective brake activation”(Landing on Contaminated
Runways, para.4). It is quite clear that the failure by the pilots to activate the thrust reversers was
costly even if it was a matter of seconds, a couple of seconds is a lot of time for aircraft on
runways, especially for a 737. The NTSB issued its own analysis and findings on the incident
after two years of research. Much of the focus was on the topic of the system of runway surface
conditions between pilots and air traffic controllers. The first finding states, “Finding 18:
‘Guidance on braking action and contaminant type and depth reports would assist pilots, air
traffic control, operator dispatch, and airport operations personnel in minimising the subjectivity
and standardisation shortcomings of such reports.’”(Parsons,2023, para. 6). And the second quote
from NTSB states that “Finding 22: ‘Establishment of a means of correlating the airplane's
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braking ability with the runway surface condition would provide a more accurate assessment of
the airplane's basic landing performance capability’”(Parsons, 2023, para.6). These findings help
identify threats to pilots and their flights by realizing that what the ATC controller sees from his
position and what the aircrafts performance will be when it lands can be very different. After
incidents like this one in Chicago at Midway international, it is easy to see why it is so important
for ATC to have a good understanding of what the braking conditions are like on the runway
during precipitation of any kind. Snow and ice should warrant additional caution and cause larger
safety margins when deciding to land in IMC conditions. Personal minimus, doing the right
things, and being aware of surroundings are all things these pilots should have given a little more
thought before deciding to vector to finals to land.
Although this incident did cause a life to be lost it was a valuable lesson learned in the
aviation world. There were several areas that were improved upon after this incident in 2005 that
helped make flights safer so that there would not be another plane sliding off the runways. The
first big implication from this is that aviation companies would have continued to not properly
train their pilots on new technology and equipment added to their fleet of aircraft. Southwest
disregarded training their pilots adequately on how to use the new auto braking system and it led
to an incident that cost a human life. Southwest was fortunate that it was only one casualty, there
could have easily been many more lives lost which would have been a nightmare for Southwest.
But because of this incident Southwest and many others made sure that if they added new
technology it needed to be taught to the pilots so that they knew how to use it so that it would
lighten the workload, not increase it and cause complications. Another rather important
implication was adding safety margins to the landing distances of aircraft. Procedures were made
by all airline operators to make sure they could calculate arrival distances to prevent any more
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runway incidents. “In August 2006, the U.S. Federal Aviation Administration (FAA) issued a
safety alert for operators, SAFO 06012, ‘urgently recommending’ that all jet airplane operators
develop procedures for arrival calculations. The alert further recommended that ‘once the actual
landing distance is determined, an additional safety margin of at least 15 percent should be added
to that distance’”(Lacagnina, 2008, pg.6). The implications that come from what happened
December 8, 2005, has most likely prevented aviation accidents/incidents and saved lives. It is
important that when an accident or incident occurs the aviation community such as the FAA,
NTSB, and ICAO, learn from it to make air travel safer than it already is.
After going over the causes, decision criteria, analysis, and implications of Southwest
Flight 1248 it is important to view recommendations and input some personal ones as well on
how mistakes seen from this flight can be prevented. At this point, it has been discussed that
there were multiple causes or threats from the Swiss cheese model that all built up to this
incident. So the recommendations should be addressed to each threat because there was no one
singular event that triggered this incident. The first cause that should be addressed is the failure
of Southwest to provide clear guidance and consistent training so the pilots were proficient in
their aircraft with the new technology. So some clear and obvious recommendations here are that
Southwest should and thankfully did change their training methods soon after the events on
December 8th at Chicago Midway International Airport. If Southwest properly trained their
pilots with new procedures that included the auto brakes properly the flight would not have
rolled off the runway. “Post-accident calculations showed that, if the pilots had promptly initiated
and maintained maximum reverse thrust throughout the landing roll, the airplane would not have
run off the end of the runway. Therefore, the Safety Board concludes that the pilots would have
been able to stop the airplane on the runway if they had commanded maximum reverse thrust
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promptly after touchdown and maintained maximum reverse thrust to a full stop”(Albright, 2019,
pg.3). It just goes to show how important it is and what a huge mistake Southwest made here, if
they had provided proper training they could’ve prevented the incident at Midway international.
The second cause is the “programming and design of its on board performance computer, which
did not present inherent assumptions in the program critical to pilot decision-
making;”(Albright,2019, pg.4). The programming and design did not take into account the 737
computed the reverse thrusters into the stopping margins, so when the pilots failed to use the
reverse thrusters upon touchdown they did not realize how dangerous the situation had become.
The recommendation here should be that the 737-700 model computer needs to be clearer
regarding the use of reverse thrusters so that pilots know when or when not to initiate an
approach to land. The next cause would be the failure to implement a familiarization period for
the pilots to learn how to use the auto brakes properly before using them immediately with
passengers on board. The recommended solution for this cause would be for Southwest to
implement training time in the simulators for the pilots. That way when something new like the
auto brakes is introduced pilots will not be distracted determining how and when to use
something that is new on the aircraft. The fourth cause that contributed to the crash would be,
“failure to include a margin of safety in the arrival assessment to account for operational
uncertainties. Also contributing to the accident was the pilot’s failure to divert to another airport
given reports that included poor braking actions and a tailwind component greater than 5
knots”(Albright,2019, pg.4). A recommendation here that could be again applied from this course
is to maintain situational awareness of the weather surroundings and do the right thing. The
pilot's decision to try and land at Chicago was not the right decision, the conditions were poor
and endangered the safety of the flight. The last and final contributing cause was the absence of
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any sort of engineering material of an arresting system, also known as EMAS, to help the aircraft
come to a stop before it exited the runway. This leads to the last recommendation that has been
applied in many airport runways today, its very purpose is to help aircraft like flight 1248 that
ran out of runway to slow down if their brakes and thrust reversers were not enough to bring
them to a stop. EMAS has helped save many aircraft, “ According to the FAA, as of January 5,
2022, there are 115 EMAS beds installed at 67 airports in the United States. Since the
completion of the EMAS installations, there have been 18 incidents where EMAS has safely
stopped overrunning aircraft, which carried 419 crew and passengers (FAA, 2022)”(Gorman,
White, 2022, pg.11). The incident of Southwest flight 1248 provided valid reasons that airports
should create and implement some sort of arresting material to help stop aircraft from sliding off
of runways due to hazardous conditions or emergencies. Overall, airline operators, pilots, and
government branches related to aviation learned from many of the mistakes of the incident on
December 8, 2005. Because of it, airline travel has become safer than it was after the crash and
that is always the most important goal. Hopefully, all the areas of the aviation industry continue
to learn from prior accidents and incidents to continue making air travel as safe as possible for
everyone involved.
The incident of Southwest Flight 1248 at Chicago Midway International on December 8,
2005, was an unfortunate event in the aviation world. Many mistakes were made by the pilots,
airline operators such as Southwest, and how ATC reported runway conditionts at the time.
Crucial changes have been made following this incident in 2005, airline operators have learned
to properly train their pilots with new technology and equipment added to their fleet of aircraft.
For pilots, it is very important that we know the ins and outs of our aircraft when flying,
proficiency must always be present. Flying an aircraft while being unfamiliar or unsure of how to
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work certain equipment can lead to disaster so it is very important that proficiency is always
present in the cockpit. There are many general aviation accidents that have happened because
pilots were not as proficient as they should have been with autopilot, characteristics of a new
aircraft, flying several people, etc, and it cost them their lives. But pilots should also continue to
learn not to risk attempting any dangerous approaches to land but instead divert to their plan B’s
for the safety of their passengers. No matter how much experience we might have as pilots or the
plane we fly it is very important to never underestimate weather conditions. Experience does
equate to invulnerability when flying, it is a great tool but it should never willingly put the
straining and risk safety of the flight for whatever convenience it may bring. So when potentially
dangerous weather threatens the aircraft it is important to maintain situational awareness and
good judgment when flying so that another aircraft does not end up on the incident/accident
report.
Works Cited
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