In recent months, airline passengers have expressed much more dissatisfaction with airline service than ever before. Complaints include flight delays, lost baggage, long runway delays with little or no onboard service, overbooked flights, cramped space due to fuller flights, canceled flights, and grumpy airline employees. A majority of dissatisfied fliers merely grin and bear it. In fact, in the mid-1990s, the average number of complaints per 100,000 passengers boarded was only 0.66. For several years, the average number of complaints increased to 0.74, 0.86, 1.08, and 1.21. More recently, the figure has leveled off at 1.19 in the year 2010. In 2010, according to the Department of Transportation, Mesa Airlines had the fewest average number of complaints per 100,000 with 0.12, followed by Alaska Airlines with 0.23, and Southwest Airlines with 0.26. Within the top 10 largest U.S. airlines by number of enplanements, Delta Airlines (includes merging with Northwest Airlines) had the highest number of complaints logged against it 1.94 complaints per 100,000 passengers. Because these average numbers are relatively small, it appears that the actual number of complaints per 100,000 is rare and may follow a Poisson distribution. In this case, represents the average number of complaints and the interval is 100,000 passengers. For example, using = 1.19 complaints (average for all air complaint to the Department of Transportation could be computed as

That is, if 100,000 boarded passengers were contacted over and over, 8.54% of the time exactly three would have logged complaints with the Department of Transportation.

Things to Ponder

1.Based on the figures given in this feature, can you reach any conclusions about the rate of passenger complaints in general?

2.Passenger complaints appear to be rare occurrences. Can you suggest some reasons why this is the case?