For the second time since 2009 a Norwegian F-16, practicing strafing over an uninhabited island, mistakenly hit the one of the few structures they were not supposed to hit. In this case the sturdy tower hit contained the officers who supervise the training. In the 2016 incident none of the 20mm rounds penetrated the tower and no one was hurt. During the 2009 incident one 20mm round did penetrate the tower but no one inside was injured. Avoiding incidents like this is why such training is conducted. Pilots who have such accidents are usually grounded and then given more, carefully monitored, training.
Such training accidents are not unusual but some take place in training areas that, while remote, are not that far from people not protected by sturdy tower walls. For example in April 2008, at Dugway Proving Ground in Utah, two soldiers were driving a rented SUV about five kilometers from the part of Dugway used for live firing by F-16s. It was at night, and an F-16 that thought it was firing at something in the live fire area, lit up the SUV instead. The two soldiers in the vehicle survived, as did the SUV (sort of, it was hit six times).
The SUV was hit because the pilot, during a night training exercise, was momentarily distracted while closing in on a target about 2.5 kilometers from where the SUV was moving down a road. Only 70 20mm rounds were fired. Fortunately, the two people in the SUV were only injured. Both driver and passenger were cut by flying glass and the passenger got a dislocated shoulder as he rapidly exited the vehicle after it turned off the road and stopped.
The pilot, a veteran of over 800 flight hours in F-16s, was immediately grounded. The pilot was using night vision goggles, which are notoriously tricky to use ("like looking through a straw" is the most typical user description). The pilots wingman was using a Sniper Advanced Targeting Pod, which is preferred, but costs a lot more (as in about a million dollars) than the night-vision goggles. So pilots train with both, but prefer the targeting pod. The wingman had illuminated the correct target with the pods laser designator. But flying low enough to strafe at night requires that the pilot pay close attention to altitude and the ground. One F-16 was lost in Iraq when it came in low at night to use the 20mm cannon, and hit the ground. The pilot died. As a result, the air force has encouraged pilots to train more for this sort of thing.
The 20mm fire is appreciated by ground troops because it can be very accurate, especially in an urban environment, with lots of innocent civilians close by. The terrorists in Iraq and Afghanistan like to hide out among civilians, and often the only solution for that (if you can't send in some troops) is to put a few dozen 20mm shells into the room where the bad guys are.
"Training errors" are normally not something a pilot gets punished for. That's what training is all about. Making mistakes and learning from that. But the shot up SUV and two shaken soldiers brings back memories, especially among infantry and marines, of the many friendly fire incidents there have been over the last 70 years. Not so much anymore, thanks to smart bombs and GPS. But the memories fade slowly.
The grounded pilot was training for deployment, with his squadron, to Iraq for a four month tour. Over the next few years pilots got better night vision gear and improved Targeting Pods which largely eliminated the problems related to night vision goggles. The most recent versions of flight helmets have visors that can display what night vision sensors on the aircraft (or a targeting pods) can see and, in effect, replace night vision goggles.