To provide a modicum of all-weather capability to the Skyhawk, Douglas added a small radar to the nose of the A4D-2N. This was to provide terrain clearance during a descent in instrument conditions to 1,000 feet above ground level, where the pilot was hopefully in visual flight conditions. (A simple autopilot was also added to reduce pilot workload when he was on instruments.) The attack still had to made visually as the radar provided no means for targeting. According to the service acceptance trials report, "It must be recognized that the capability is marginal and requires highly trained pilots thoroughly qualified in radar navigation techniques."
Note the anti-flash hood behind the pilots head that he would pull over the cockpit during the bugout after delivery of a nuclear weapon to reduce the risk of injury and damage from the thermal effects of the nuke's detonation.