air marshals were arrested 148 times from November 2002 through February 2012. There were another 58 instances of criminal conduct.
In addition, air marshals engaged in more than 5,000 less serious incidents of misconduct, ranging from 1,200 cases of lost equipment to missing 950 flights they were supposed to protect.
250 air marshals have been terminated for misconduct; another 400 resigned or retired while facing investigation.
Air marshals have been suspended more than 900 times, resulting in more than 4,600 days lost to misconduct.
The Washington field office had the most incidents with 530 cases, followed by New York with 471, Chicago and Dallas with 373 each and Los Angeles with 363. There were 85 cases at air marshal headquarters, highlighting that in some cases, misconduct has extended to the top brass.
So since they arrest about 4.2 people per year since 2001 that means more Air Marshalls have been arrested than cases of Air Marshalls arresting people.
I feel so much safer with them on duty and forgetting loaded firearms in airport bathrooms and doing other fun things like these:
In 2003, a New York air marshal pulled his gun in a dispute over a parking space. Another failed to turn over his ammunition on an international trip, as required by diplomatic agreements, and was detained by Israeli airport security in 2004. That same year, a Las Vegas air marshal "discharged" his gun in a hotel room, penetrating a wall and shattering a mirror. In April, a Phoenix air marshal fired his during a fight outside a bar.
Still another left his handgun in the plane's lavatory in 2001, according to court papers. He realized it was missing only after a teenager found it.
More fine benchmarks for the TSA
http://usatoday30.usatoday.com/news/washington/2008-11-12-air-marshals_N.htm
https://www.propublica.org/article/tsa-releases-data-on-air-marshal-misconduct-7-years-after-we-asked