It's unlikely the safety of the planes was at risk since the pilots would have used a radio frequency for the airport tower to advise nearby aircraft of their intention to land and to make sure that no other planes also intended to land at that time, aviation safety experts said. At that time of night, air traffic would have been light, they said.

 

Also, controllers at the regional facility, using radar, would have been able to advise the pilots of other nearby planes, experts said.

 

The primary risk would have been if there was equipment on the runway when the planes landed, they said.

 

But the incident raises serious questions about controller fatigue, a longstanding safety concern, said John Goglia, a former NTSB board member.