The head of air traffic control in the United States has resigned following a series of recent incidents in which traffic controllers were found sleeping on the job at night.
In the latest such incident on April 13, a medical plane carrying a critically ill patient had to land without guidance at an airport in Nevada after the air traffic controller fell asleep.
Last month, two planes carrying a total of 165 people were forced to land without assistance at Washington's Reagan National Airport because the sole controller on the night shift had dozed off.
The Federation Aviation Administration chief accepted the resignation of Hank Krakowski on April 14 and launched a review of how some 15,000 controllers do their job.
compiled from agency reports