An Alaska volcano that has been active for nearly six months erupted again Sunday, Bloomberg reported.

The Alaska Volcano Observatory said Bogoslof Volcano in the Aleutian Islands erupted at 2:16 p.m. Sunday and sent a cloud of ash at least 35,000 feet high. The eruption lasted 55 minutes, Bloomberg reported.

After the eruption, the Aviation Color Code was raised to red, the highest level.

Ash from southwest Alaska volcanos can be a threat for airlines operating between North America and Asia when a cloud rises above 20,000 feet, according to The Associated Press.