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MISAWA AIR BASE, Japan(DefenceTalk): Putting steal on target is the aim for warfighters, and making sure F-16 Fighting Falcon guns hit bull's-eye every time is the mission of weapon loaders at Misawa Air Base.
In a process called boresighting, weapons Airmen ensure the path of bullets shot from the 20mm cannon is aligned with pilots' targeting systems in the cockpit's Heads Up Display, or HUD.
If the gun isn't aligned properly, bullets can stray from their target despite the pilot seeing a proper aim in his display.
Different factors can lead to the cannon becoming unaligned, and a boresight must be performed after any weapons maintenance and hard landings. A boresight can't be performed after any other maintenance on the jet until it's been flown first.
“If the jet has been raised on jacks for any reason, a boresight won't be done until the jet has flown at least one time. Failure to comply may result in inaccurate boresight or degrading of weapons delivery,” said Staff Sgt. Eric Reid, a weapons trainer with the 372nd Training Squadron here.
Sergeant Reid trains Airmen to do a proper boresight on real F-16s and mock-ups. On the first day of training he shows them how to install the framework and mounts required on the actual jet. The final process of finding the aircraft boresight reference line, or good alignment of the cannon is matched with the HUD, is done on the mock-up.
“We like to keep off the aircraft as much as possible, allowing the fighter wing to use their aircraft for fighter missions and training. So we like to use our trainers as much as possible,” Sergeant Reid said.
The trainer is equipped with two scopes, one on each end of the training aircraft. The telescope at the back end, the boresight telescope, allows Airmen to look along the path of the cannon to the targeting scope on the other end, or the collimator.
An Airman stands at each, with the person at the rear looking through the boresight telescope. Inside he sees a scale and two crosshairs; one is from the collimeter. This Airman directs the other person at the targeting scope where to move it so that the cross hairs match.
“I tell him to go down and then it'll go down a little bit, but then it'll jump every once in a while and go a lot. And (you) try going back left and it'll move in other directions too,” said Airman 1st Class Jared Clark, a weapons Airman with the 13th Fighter Squadron.
The touchiness of the collimeter makes for a difficult boresight.
“When you make a little adjustment here, it can drive the other one to go up and down accordingly. So it's a touchy-feely type of process and can be a bit tedious at times,” Sergeant Reid said.
A reading is taken from the scale inside the scope, and an average is made. That average must be within a certain boresight tolerance, and if it is then the cannon is firing where the HUD says it is. When it isn't in tolerance, adjustments must be made to the gun system and a stricter boresight is established.
The entire boresight process takes about three hours, but if a full boresight was performed recently then weapons Airmen can instead opt to do a quick check, which takes about 30 minutes.
