It’s not uncommon for heads to roll after a safety scandal, so the resignation of Hank Krakowski, the FAA chief operating officer for air traffic, on Thursday morning came as no surprise.

Krakowski stepped down after several highly publicized instances of air traffic controllers sleeping on the job.

In the latest incident on Wednesday, a controller snoozed while a medical flight carrying a critically ill passenger tried to land at Reno-Tahoe International Airport.

David Grizzle, the FAA’s chief counsel, will be taking over for Krakowki in the interim.

According to Transportation Secretary Ray LaHood, there are currently five ongoing FAA investigations looking into reports of sleeping controllers.

According to a FAA report released this year, mistakes made by air traffic controllers have doubled from 2009 to 2010.

By Adriana Padilla for PeterGreenberg.com.

Related Links: Dallas Morning News

Related Links on PeterGreenberg.com:

• Washington’s Reagan National Airport Air Traffic Controller Allegedly Falls Asleep, Putting Planes At Risk
• Air Traffic Controller Mistakes Double As Serious Safety Incidents Reported
• Near-Miss At SFO: Airline Safety At Major Hubs
• What Does It Take To Be An Air Traffic Controller?
• Air Travel News: Airlines & Airports section