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Firdu Bati Video Presentation on Aviation Safety Introduction • Aviation safety is very important to the viability of the industry in general • Frequent Fatal accidents can have high negative effect in the perception of the flying public and damages the industry’s reputation • Fortunately, aviation accidents are very rare, and only a fraction of those accidents result in fatalities • The likelihood of being killed in aviation accident is extremely small, in the order of millionth Death Risk • An objective measure of aviation safety is the death risk of flying • How likely it is a passenger wouldn't survive any randomly chosen flight • To determine the death risk, we rely on statistics of various kind. • We need to be careful about the type of statistics to consider for death risk analysis • Static of “fatal accidents per hours flown” may not be a good measure. - The variable “fatal accident” may represent an accident with a single fatality or entire passengers of the flight with the same weight. - Similarly, “hours flown” ignores some important facts such as most accidents happen in certain phase of flights regardless of number of hours flown Death Risk • “Hull loss” statistic is more useful to aircraft manufactures than assessing death risk - An accident with heavy damage to the aircraft might involve no deaths at all • “Passengers killed” to “passengers carried” statistic is a good measure of proportions, but still don’t truly measure death risk - The risk is not proportional by the number of passenger in a given accident, i.e. accident with higher number of fatalities is not proportionally riskier than with small number of fatalities • In general, it is better to avoid directly involving the number of deaths in the numerator of death risk statistics Death Risk Using Q-statistic • The Q-statistic answers the probability of death given a random flight of N flights with xi fraction of fatalities - Let there be N flights to choose from - A flight i is picked with 1/N probability - xi is the fraction of deaths in flight i - The conditional probability of death in flight i is xi /N - Full Loss Equivalent-FLE is the sum of the fraction, ∑xi - Overall probability, which is the death rate over all N flights is given by: Q = ∑i=1-N xi /N = FLE/N Advantages of Using Q-statistic • Q-statistic allows to treat accidents with higher survival rate differently than with lower survival rate • It doesn’t give different weights to Distance flown and duration of flight • The conditional probability calculation involved in Q-statistic is very easy • Q-statistic calculated using recent data can be used to estimate death of on other flights Calculated Q-values • Using data of scheduled passenger jet flights in First World countries – In year 1990 to 1999, 70 million flights performed with only 10 of them involved in fatal accidents – Average fraction of the 10 flights is 56% – Q= 10*0.56/70,000,000 = .00000008 which equates to approximately 1 fatality in 13 million flights, a very, very small fraction – With such a small rate, a person can fly everyday for 36,000 years before killed in a flight accident Calculated Q-values • Recent statistics show even impressive results - From 2000 to 2008, there were only 2 accidents, one in Kentucky in 2006 with 100% fatality and another one in Madrid in 2008 with 90% fatality of 80,000,000 flights total - Average fraction of the 2 fatal flights is 95% – Q= 2*.95/80,000,000 = .000000024 which equates to approximately 1 fatality in 42 million flights – With such tiny rate, a person can fly everyday for more than 116 thousand years before killed in a flight accident Note: Not considering survivability, the death risk tends to be higher Statistic Across the World • First World Domestic - 1960-1969 1 in a million - 1980 – 1989 1 in four million - 2000 – 2007 1 in 80 million • First World International - 1960-1969 1 in 200 thousand - 1980 – 1989 1 in four million - 2000 – 2007 1 in 9 million • Between First and Developing World - 1960 – 1969 1 in 200 thousand - 1980 – 1989 1 in 600 thousand - 2000 – 2007 1 in 1.5 million • Within Developing World - 1960 – 1969 - 1980 – 1989 - 2000 – 2007 1 in 100 thousand 1 in 400 thousand 1 in 2 million Comparing Safety Among Operators • With such a small overall death rate in the First World, it would be difficult to make detailed comparison among individual airlines • One approach would be to compare the rate of precursors to accidents • Using Incidents and non-fatal accidents to compare death rate among airlines however might not reflect the true picture. • Typically, airlines learn from incidents and take corrective actions to minimize the occurrence of accidents from same operational errors • Even when a First World airline is compared with Third World airline in the same environment/route, the rate is surprisingly similar. • Hence, there is no statistically significant data to claim that one airline is better than another in terms of safety Future Aviation Safety Assessment • The fact that aviation accidents rate have reduced to such level in recent decades is a testament to the safety record of the industry • However, how do we improve safety further in the presence of almost non existent accidents from which operators and regulators learn and take actions to prevent such happenings • Because of that, since the early 1970 the industry and regulators started compiling data about incidents which are precursors to accidents • There are over 70 safety action programs run by airlines, NASA and the FAA to collect data that lead to incidents which have the potential to lead to accidents • As a result there are enormous amount of data to analyze and assess the future of aviation safety, and the likelihood of catastrophic accidents • Linear and Quadratic models can be used to assess runway and mid air collision risks of future operations Conclusion • The statistics undeniably tells the whole picture, safety of aviation has been improving at an impressive rate in spite of increasing service • However, the system is not completely free of accidents, when aviation accidents do happen, they leave large dents in the industry and erode public confidence • We have to continue to improve the system as challenging as that maybe • With the expected increase of aviation services and the introduction of new procedures and application of latest technologies, the challenges will be even greater • No matter how challenging the task is the safety of aviation should not be comprised and needs to continue to improve to sustain the viability of this vital industry References Chapter 11, Aviation Safety from Global Airlines Industry by Belobaba, Odoni, and Barnhart Aviation Safety Lecture Notes by Dr. Lance Sherry