The United States transportation authority (TSA) has extended until January 18 a requirement that people on airline flights and public transportation wear face masks to limit the spread of COVID-19. The mask rule also applies to employees on planes and public transportation.

The mask mandate has led to many encounters between anti-masker passengers and flight attendants asked to enforce the rule. The Federal Aviation Administration said Tuesday that airlines have reported 3,889 incidents involving unruly passengers this year, and 2,867—or 74%—involved refusing to wear a mask. A recent surge in COVID-19 cases linked to the delta variant. The seven-day average of new cases has topped 140,000, an increase of 64% from two weeks ago and the highest level in more than six months.

The US Travel Association said the extension “has the travel industry’s full support.” The largest union of flight attendants said the move will help keep passengers and aviation workers safe.