Date of Award


Document Type


Degree Name

Master of Science (MS)




Every airline union claims to work for safety and presents anecdotes where greater airline safety has been achieved through union efforts. The effect unionization has on safety outcomes in U.S. commercial airlines, however, wasn’t found to be previously tested. Studies have shown that in industries such as coal mining, retail, and construction, unionization does lead to an increase in safety. This study evaluated the safety rates of 15 major US commercial airlines to compare the difference between unionized and non- unionized airlines. These safety rates were compared based on if and how long each airline’s pilots and flight attendants have been unionized, to determine if unionization had an effect on safety outcomes. The 15 airlines included in the study identified as operating most of the years between 1990 and 2013, with annual departures averaging over 130,000, available through the Bureau of Transportation Statistics. Accident and Incident information was acquired through the National Transportation Safety Board database. The number of accident and incidents divided by the total departures at each airline was used as the safety rate. Union websites provided information on unionization at the airlines. Due to the complex nature of the aviation industry, a number of confounding factors could have affected the tests, including mergers, route structures, and legislation. To help control for these confounding factors, this study was limited to airlines with a stable presence in the industry over time, which limited the number of airlines included. No significant difference was found between unionized and non-unionized airlines in this study, though the mean safety rate of unionized airlines was found be better than non-unionized airlines. This study did not take into account safety improvements that were union-backed and eventually required at all airlines, regardless of unionization. Due to the large sample size of the small population the difference in safety rate means could be indicative of greater safety in unionized airlines.