Air traffic controllers are back at work at McCarran International Airport in Las Vegas, a week after a co-worker tested positive for the new coronavirus. The Federal Aviation Administration posted an update Wednesday saying that staffing should increase throughout the day. Airport service slowed due to airline cancellations and delays were reported after the control tower closure on March 18. McCarran ranks as one of the busiest passenger airports in the nation. But arriving flights were reduced Monday to about 12 an hour. Federal officials reported Tuesday that a security screener at McCarran also tested positive for COVID-19.