In early October something rare and strange happened in eastern Afghanistan; an American F-16 came back to base shot up by bullets fired from the ground. That rarely happens. The air force would not say what the circumstances of this incident were, meaning that the F-16 was probably coming in low to strafe targets that were threatening a commando operation. The enemy may have been so close to a small team of SEALs or Special Forces that it was too risky to use a smart bomb. But with current gunsight technology an F-16 pilot can come in low and hit a small target with the 20mm autocannon. In this case there were a lot of bad guys down there with machine-guns because many of them must have been firing on the F-16s. The pilot was forced to jettison two drop tanks, a missile and two bombs before returning to base. Normally F-16s stay high enough to avoid machine-gun fire but train to come low and strafe, just in case.
As the air force is planning to retire the A-10C ground attacks aircraft more attention is being paid to preparing some F-16 pilots to replace A-10s for low altitude work. The A-10 was designed for low level strafing, using a 30mm cannon, but F-16s, with a new, and more capable gun sight, have proved to be very effective at strafing. However, F-16s moves faster than the A-10, and it is more difficult to control on the deck. That's a necessary trade-off, because the F-16 is a multi-mission aircraft, while the A-10 just does ground support.
There are other dangers for F-16s that come in low. In 2006 an F-16 pilot was killed when, on a low level strafing run in Iraq, when he was momentarily distracted and his aircraft crashed. The U.S. Air Force considers it an acceptable risk to come in that low to use its 20mm cannon on a ground target. Because of safety concerns, pilots are not allowed to perform that kind of maneuver during peacetime training. Since it's now wartime, such training is allowed. That training can be risky in other ways. In 2008 an F-16 was practicing firing at ground targets at night (where much of the action takes place in Iraq), became momentarily distracted, and shot up an SUV on a nearby highway.
While F-16 pilots are willing to come in low and use their cannon, the F-16 was not designed for this sort of thing. The aircraft is too fast. An F-16 coming in low to use cannon on ground targets is going at least 400 kilometers an hour. The A-10 can slow down to 250 kilometers an hour. In addition, the A-10 is designed to more easily maneuver down low and slow, and is armored to better survive ground fire. Not so the F-16. But the air force insists the F-16 can do the job, and pilots die as a result.
What the F-16 can do is carry a dozen or more smart bombs, and in that role it is very useful to the ground troops. The newly upgraded A-10Cs can also carry smart bombs.