On 8th March 2014 Malaysian Airlines flight MH370 to Beijing disappeared within less than an hour after taking off from Kuala Lumpur in the “dead space” between Malaysian and Vietnamese Air Traffic Control (ATC). Just before the last radio message, ACARS, the on-board system that sends performance information, had stopped functioning and the transponder which communicates a plane’s position had been switched off. Without these mechanisms to communicate with the outside world the aircraft appeared to have disappeared.
It was discovered that there was one data source that could give insight into the path that MH370 had taken that night. There were automatic ‘pings’ that were sent between the Inmarsat satellite and the plane and the Inmarsat satellite and the ground station. The ‘ping’ is sent once an hour to record whether a plane is still logged on but it does not contain any location information. This data confirmed that the plane had continued flying between six and seven hours after the last communication.
A large amount of data analysis and new way of modelling was involved in trying to figure out the path that the plane took after the communication ceased. The analysis used the time between the sending and receiving of the ‘ping’ signal to calculate two arcs of possible locations of the aircraft, a northern and a southern corridor. It used the velocity of the aircraft relative to the satellite and the change in signal frequency known as the Doppler Effect (the reason why police or ambulance sirens sound different when coming towards you compared to going away from you) and compared the data with six other Boeing 777 flights flying in different directions on the same day. The analysis had good match with the southern corridor. Knowing the direction the plane was flying and the time before it went down it was concluded that the aircraft likely went down in the South Indian Ocean, somewhere west of Australia.
This terrifying, mysterious and extremely sad incident has evoked the question about how safe it is to fly. I am particularly interested in this as in a couple of weeks’ time I am due to fly to the Indian Ocean. Should I cancel the holiday and stay home instead?
Over the past 20 years the probability of being killed in a flight accident when flying with one of the 78 major world airlines has been 1 in 4.7 million. Fly with one of the top-39 airlines and the probability goes down to 1 in 19.8 million. Flying with the safest airlines further reduces the probability of accidents dramatically. For example, British Airways has had no fatal accidents over the past 37 years and they have over 40 million passengers annually.
Most of the accidents are caused by a combination of events, as reported for example in National Research Council’s book Improving the Continued Airworthiness of Civil Aircraft, which alone would not cause the accident but together lead to a crash. According to research on accidents, often it is a combination of bad weather, minor technical issues, the flight being behind schedule so it is hurrying, pilot being tired and unable to think sharply and the pilots not being comfortable with each other.
A typical accident involves on average seven consecutive human errors. The errors that cause planes to crash are invariably errors of teamwork and communication. In his book Outliers Malcolm Gladwell highlights the role of the cultural background of the pilots and the significance of having a low ‘power distance’ between the pilot and the co-pilot. Historically, crashes have been far less likely to happen when the co-pilot, not the pilot, is flying. This is because then the second pilot (in these cases the more senior pilot) is not afraid to speak up. In accident investigations, psychologists play an important role analysing the recordings from the cockpit.
Understanding of the causes of accidents has led to more efficient training and consequently the safety of flying has increased significantly. The past five years of passenger flight accident data show that the probability of being killed in a flight accident has been 1 in almost 7 million. Choose one of the safest airlines and you are more likely to be killed by a vending machine than in a plane crash.
A closer look at the accident data over the past five years would suggest that, statistically, flying on a Friday might minimise the probability of an accident (data not normalised).
Data source: www.planecrashinfo.com
Also, this data suggests that an intercontinental flight may be safer than flying within a continent. Actually, a third of all passenger flight accidents happened on flights within Asia.
Data source: www.planecrashinfo.com
This analysis has given me reassurance that the risk of something very bad happening on my flight to the Indian Ocean (Saturday, Europe to Africa, British Airways) is very small and I am ready to take it. The risk of getting killed in London traffic is probably higher.
Follow Maija Antila @maija_antila