The head of the Federal Aviation Administration's Air Traffic Organization resigned Thursday, the day after another air traffic controller was caught napping while planes were trying to land.
"Hank Krakowski has submitted his resignation and I have accepted," FAA Administrator Randy Babbitt said in a statement. "Hank is a dedicated aviation professional and I thank him for his service."
Krakowski had held the position since 2007 and prior to joining the FAA had worked for United Air Lines for nearly 30 years, says his FAA bio.
Krakowski's resignation comes as the FAA investigates five incidents in recent weeks of air controllers possibly sleeping on the job.
Following the most recent incident on Wednesday in Reno, Nev., the Federal Aviation Administration and the Department of Transportation announced that additional air traffic controllers would be immediately added on the midnight shift at 27 control towers that currently have only one person working overnights.
President Barack Obama said Thursday that air traffic controllers falling sleep in unacceptable. "The fact is, when you're responsible for the lives and safety of people up in the air, you better do your job."
Obama told ABC News' George Stephanopoulos in an exclusive interview that the answer begins with personal responsibility, but the FAA and the Transportation Department are conducting a "full review."
"I'll be grabbing the agency by the ears," Transportation Secretary Ray LaHood said in a separate interview with Stephanopoulos on Wednesday. "We've done some grabbing today with the outrage that we have expressed and the suspension of this controller and the investigations. And there'll be more to come, George. I guarantee the flying public we will not sleep until we can guarantee that there's good safety in the control towers when these planes are coming in and out of airports."
Feb. 19 - A controller in Knoxville, Tenn., went to sleep on the job during a midnight shift. Sources told ABC News that the controller made a bed on the floor of the control tower with couch pillows.
March 23 - A controller on his fourth consecutive overnight shift at Washington, D.C.'s Reagan National Airport left the radio tower silent after apparently falling asleep. Two commercial airliners were forced to land on their own.
March 29 - Two controllers at Preston Smith International Airport in Lubbock, Texas, did not hand off control of a departing aircraft to another control center and it took repeated attempts for them to reached.
April 11 - A controller at Boeing Field/King County International Airport in Seattle fell asleep on the job. Boeing Field does not handle any commercial air travel.
April 13 - A controller at the Reno-Tahoe International Airport in Nevada was sleeping as a plane carrying a crticially ill patient was trying to land.
ABC News' Andrew Springer contributed to this report