NEW YORK (MainStreet) -- Measuring airline safety is tricky business. After all, accidents happen and planes don't fly unless they meet clearly established company and national safety guidelines, so it's hard to pinpoint what makes one carrier "safer" than another. Do you measure based on the number of incident reports authorities investigate? Or based on an ability to efficiently manage flights and planes while serving passengers?

The variety of metrics is what led research group the Air Transport Rating Agency to devise its own "holistic" ranking that takes into account 15 criteria that consider direct and indirect factors affecting airline safey. It did so for the world's 100 most important airlines from 2009 and found comprehensive data for 44 of them.

The resulting ranking, the group hopes, will encourage air carriers to look at safety in a bigger way to ensure a more nuanced commitment to operating at the highest level possible.
There are many ways to measure airline safety, but one research group thinks it's got the formula to put its ranking on solid ground.

"ATRA wanted to provide the aviation sector with rigorous and transparent information, liable to encourage airlines to track, interpret and discuss any criteria in the organization contributing to flight safety," the organization writes on its website.

There are two factors that set ATRA's ranking apart from other rankings of airline safety: It considers organizational features of different air carriers and does so using a mathematical analysis that gives different weights to different measures.

"After analyzing the causes of a number of incidents and accidents, ATRA has selected 15 organizational criteria, which directly or indirectly contribute to general safety," the organization notes. "Illegal activities have not been taken into account, as it has been assumed that security check persons and luggage is under the responsibility of airport services."

Here are the 15 criteria ATRA used to come up with the world's 10 safest airlines:
  • Net financial result
  • Total number of passengers
  • Total number of employees
  • Total number of cabin crew employees
  • Total number of aircrafts
  • Average fleet age in service
  • Percentage of aircrafts on order
  • Fleet homogeneity
  • Number of aircrafts no longer in production
  • Number of aircrafts considered at risk
  • Total aircrafts-km flown
  • In house maintenance capability
  • Number of accidents during the past 10 years
  • Dedicated flight academy pilot-training facilities
  • Dedicated full flight simulators

With these 15 factors in mind, here are the world's safest airlines according to ATRA:
  • Safest airline 1: Air France/KLM
  • Safest airline 2: American Airlines/American Eagle
  • Safest airline 3: British Airways
  • Safest airline 4: Continental Airlines
  • Safest airline 5: Delta Airlines
  • Safest airline 6: Japan Airlines
  • Safest airline 7: Lufthansa
  • Safest airline 8: Southwest Airlines
  • Safest airline 9: United Airlines
  • Safest airline 10: U.S. Airways

>To submit a news tip, email:

Follow on Twitter and become a fan on Facebook.