Police harbor officers are using sonar-equipped boats and working with a sonar expert from the National Oceanographic and Atmospheric Administration as they search the area where the plane came down Thursday, near the Intrepid Sea, Air & Space Museum. The NYPD is also monitoring the river from the air because sensitive equipment could be damaged by ice and must be removed if the river gets too icy.
Factory-installed Police Perimeter Aler uses sensors to monitor an approximately 270-degree area around the vehicle. It detects nearby movement to alert officers of any suspicious activity. When such motion is detected, the system automatically turns on the rear camera, sounds a chime, rolls up the windows, and locks the doors.