HY! this is Mateen. In this presentation you known about top 10 major disaster in which involve computer directly or indirectly .Explain how a little bit mistake in software can turn a major blunder. This presentation is inspiration for computer science student to know about their professional responsibility's in workplace.

1. Major Blunder by
Computer software Bugs
Unreliable software's
M.Mateen & Zainab Tariq
BSCS(evening)-B
5024,5040
University of Okara
Professional Practices

2. Unfortunately, millions of users
around the world have come to
realize the latter over recent
years due to unwelcomed,
failures.
Technology, you can’t live
with it, you can’t live without
it.

3. 3
The Truth
 Hundreds of thousands
of software projects fail
everyday
 Software companies, not
eager to share disaster
stories
 Reducing the number of
software failures is one of
the most challenging
problems of software
production.

4. You now have a system
that’s very efficient at
burning money
In history Computer also involve
in directly or indirectly human
casualties

5. Historical Major Software Bugs to
Extreme consequences
UNDETECTED HOLE IN THE
OZONE LAYER
Based on the analysis of long-term
datasets of ozone from two ground-
based stations in Antarctica, British
Antarctic Survey scientists first
discovered the ozone depletion and
reported their observations in May 1985
in the journal Nature.
 People were wondering why there was
no corroborating evidence from NASA
satellites
5

6. NASA Fail to detect
ozone layer due to
software
 The hole in the ozone layer over
Antarctica remained undetected for a
long period of time because the data
analysis software used by NASA in its
project to map the ozone layer had been
designed to ignore values that deviated
greatly from expected measurements.
 The project had been launched in 1978,
but it wasn’t until 1985 that the hole was
discovered, and not by NASA. NASA
didn’t find the error until they reviewed
their data, which indeed showed that
there was a big hole in the ozone layer.

7. 7
DEADLY RADIATION THERAPY
• The Therac-25 medical radiation therapy
device was involved in several cases where
massive overdoses of radiation were
administered to patients in 1985-87, a side
effect of the buggy software powering the
device. A number of patients received up to
100 times the intended dose, and at least three
of them died as a direct result of the radiation
overdose.
• Another radiation dosage error happened in
Panama City in 2000, where 21 who died in
the following years did so as a result of their
cancer or ill effects from the radiation treatment

8. • It was involved in at least six accidents
between 1985 and 1987, in which
patients were given massive . Because
of concurrent programming errors (also
known as race conditions. These
accidents highlighted the dangers of
software control of safety-critical
systems, and they have become a
standard case study in health
informatics and software engineering
Deadly software

9.  In the last century, software developers had never
thought that their code and creations would
survive into the new millennium. For this reason,
many assumed that writing “19” before the
variable “year” was an unnecessary waste of
memory. Most decided to omit these two digits.
 All good until the turn of the century: the closer
we got December 31st, 1999, the more we
started worrying about the fact that computer
systems in New Year’s Eve would update their
clock to January 1st, 1900 instead of 2000 and,
because of this, major disasters would be
unleashed and it would be the end of mankind
The Y2K Bug
Mostly computers fail to update
there calendars

10. Y2k
consequences
The Y2K bug was real,
nevertheless. Billions of dollars
were spent in order to upgrade
computer systems worldwide.
Also, some small incidents were
reported: In Spain, some
parking meters failed. The
French meteorological institute
published on its website the
weather for January 1st 19100
and in Australia, some bus-
ticket validation machines
crashed.

11. THE DHAHRAN SCUD
MISSILE
11
• In February 1991 (First Gulf War), an Iraqi
missile hit the US base of Dhahran in Saudi
Arabia, killing 28 American soldiers.
• Following an investigation, it was determined
that the base’s antiballistic system failed to
launch because of a computer bug: the Patriot
missile battery, whose role is to detect and
intercept enemy missiles by “crashing” against
them in mid-air, had been running for 100
hours straight.
• After every hour, the internal clock drifted by
milliseconds and that had a huge impact on
the system (a delay of ⅓ of a second after 100
hours).

12. Impact of 0.33
Second delay
• For a person, 0.33 seconds is an
infinitesimal amount; but for a radar that
tries to track an Al Hussein Scud missile –
that reaches Mach 4.2 (1.5 km per second
/ 0.88 miles per second ), this “micro-
delay” translates into a “600 meter” error.
In the case of the Dhahran incident, the
radar first identified an object in the sky
but didn’t manage to track it due to the
error, and thus, the missile didn’t launch
itself.
• This light mistake 28 died 128 wended in
this incidences

13.  the Hubble Space Telescope's launch in 1990,
operators discovered that the observatory's primary
mirror had an aberration that affected the clarity of the
telescope's early images.
 Hubble's primary mirror was built by what was then
called Perkin-Elmer Corporation, in Danbury,
Connecticut. Once Hubble began returning images that
were less clear than expected, NASA undertook an
investigation to diagnose the problem. Ultimately the
problem was traced to mis calibrated equipment during
the mirror's manufacture. The result was a mirror with an
aberration one-50th the thickness of a human hair, in the
grinding of the mirror.
Hubble telescope
Mirror Error
CNC programming error

14. Hubble Error
correction costly
Replacing the mirror was not practical,
so the best solution was to build
replacement instruments that fixed the
flaw much the same way a pair of
glasses correct the vision of a near-
sighted person. The corrective optics
and new instruments were built and
installed on Hubble by spacewalking
astronauts during a shuttle mission in
1993. The Corrective Optics Space
Telescope Axial Replacement
(COSTAR) instrument, about the size
of a telephone booth, placed into
Hubble five pairs of corrective mirrors
that countered the effects of the flaw.

15.  bvhj
Three Mile Island
Accident
The Three Mile Island
power station is near
Harrisburg, Pennsylvania
in USA. It had two
pressurized water
reactors. TMI-1, a PWR of
800 MWe (775 MWe net)
entered service in 1974,
and remains one of the
best-performing units in
the USA. TMI-2 was of 906
MWe (880 MWe net) and
almost brand new at the
time of the accident.

16. 16
 The accident to unit 2 happened at 4 am on 28 March 1979 when
the reactor was operating at 97% power. It involved a relatively
minor malfunction in the secondary cooling circuit which caused the
temperature in the primary coolant to rise. This in turn caused the
reactor to shut down automatically. Shut down took about one
second. At this point a relief valve failed to close, but instrumentation
did not reveal the fact, and so much of the primary coolant drained
away that the residual decay heat in the reactor core was not
removed. The core suffered severe damage as a result.
 The operators were unable to diagnose or respond properly to the
unplanned automatic shutdown of the reactor. Deficient control room
instrumentation and inadequate emergency response training
proved to be root causes of the accident
Software fail to
action and not
responding

17. Air New Zealand
crash
17
• the crash was Air New
Zealand's alteration of the flight
plan waypoint coordinates in
the ground navigation computer
without advising the crew.
The new flight plan took
the aircraft directly over the
mountain, rather than along its
flank
• The crash killed 227
passengers and 30 crew.
Forty-four people were never
identified during the search
and recovery operations.

18. The pilots had been briefed
with a flight path which was
different from the one put into
the plane's computer. The
team thought their route was
the same as previous flights,
going over ice and water in the
McMurdo Sound, when in fact
the path was going over Ross
Island - and the 3,794m
volcano Mt Erebus.
Plan’s computer was
the crash reason

19.  The Mars Climate Orbiter was launched
in 1998 with the goal of studying climate
on Mars, although it never managed to
fulfill its mission.
 After traveling through space for several
months, the probe was destroyed because
of a navigation error: teams who controlled
the probe from Earth used parameters in
imperial units meanwhile the software
calculations were using the metric system.
These miscalculations had an impact on
the flight path. In the end, the probe was
destroyed because of friction with
the Martian atmosphere (an error of
almost 100 km).
FEET OR METERS?
THE MARS CLIMATE
ORBITER NAV BUG
Software calculate distance in matrices
system while Scientize in English system

20. • On June 4th, 1996 and only 30 seconds after the launch, the Ariane 5 rocket began to
disintegrate slowly until its final explosion. Simulations with a similar flight system and the
same conditions revealed that in the rocket’s software (which came from Ariane 4), a 64-bit
variable with decimals was transformed into a 16-bit variable without decimals.
• These variables, taking different sizes in memory, triggered a series of bugs that affected all
the on-board computers and hardware, paralyzing the entire ship and triggering its self-
destruct sequence.
• The fault was quickly identified as a software bug in the rocket’s Inertial Reference System. The rocket used this
system to determine whether it was pointing up or down, which is formally known as the horizontal bias, or
informally as a BH value. This value was represented by a 64-bit floating variable, which was perfectly adequate
TOO MANY DIGITS
FOR ARIANE 5

21. software-induced flight
crash
• In 1994 in Scotland, a Chinook helicopter
crashed and killed all 29 passengers. While
initially the pilot was blamed for the crash,
that decision was later overturned since
there was evidence that a systems error
had been the actual cause.
• a software-induced flight crash happened
in 1993, when an error in the flight-control
software for the Swedish JAS 39 Gripen
fighter aircraft was behind a crash in
Sweden.

22. THANK
YOU!
Zainub Tariq & Mateen