单项选择题

The Monday edition of USA Today said sixty people have died in 84 crashes since 2000. This is more than double the number of crashes during the previous five years. Its study found that more than 10 percent of the U. S. air ambulance helicopters (救护直升机) crashed during that time and about two-thirds of the fatal crashes occurred in poor visibility.
After reviewing hundreds of pages of documents and interviewing dozens of pilots, federal officials and executives with the companies that operate the flights, USA Today concluded that air ambulance companies have failed to apply safety requirements that might have saved lives. It also found that helicopters were used "excessively" for patients who weren’t severely injured.
But the newspaper also noted that there are studies which show that thousands of lives are saved each year by speedy flights to hospitals. It pointed out, as well, that pilots operate in challenging situations, such as having to land on hospital roofs and being sent on life-and-death tasks to rural accident scenes despite darkness or bad weather. "I don’t know anybody in this industry who isn’t devoted to safety and devoted to what we do," Ron Fergie, president 6f the National EMS Pilots Association, told USA Today.

We can learn from the last paragraph that ambulance-helicopter pilots often（）

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