TMA and Bearing Rate question.

Henson · 08-23-06, 05:48 AM

My recommendation (if you're really serious about using bearing rate) is to get an accurate bearing rate by creating a manual time vs. bearing plot on graph paper.

You are correct. The main thing you get from bearing rate is the overall direction of relative motion, ie is he drawing left or right of the line of sight. The problem you run into is lead vs overlead. That will more than likely require a maneuver to figure out...I will say however that if your bearing rate is low and your crossed bearings on the geoplot are relatively far away that you are more than likely looking at an overlead, while a lag will have more of a classic "fan" shape with crossed bearings significantly closer. An experienced eye will tell you that a lag simply 'looks different' from an overlead, but it's difficult to qualify in writing. The reason it's better to maneuver is because maneuvering from a lag to an overlead or vice versa will give you a minimum range on one leg and a maximum range on the other, which really helps your solution lock in nicely after only two, maybe three legs on a non-maneuvering contact.

The added benefit to a manual Time/Bearing Plot, by the way, is that it can tell you if a non-maneuvering target is opening or closing by showing whether the bearing rate is decreasing or increasing respectively. It will also show you Closest Point of Approach, which is at the point of highest bearing rate.

08-23-06, 05:48 AM	#4
Henson Planesman Join Date: Feb 2006 Posts: 185 Downloads: 13 Uploads: 0	My recommendation (if you're really serious about using bearing rate) is to get an accurate bearing rate by creating a manual time vs. bearing plot on graph paper. You are correct. The main thing you get from bearing rate is the overall direction of relative motion, ie is he drawing left or right of the line of sight. The problem you run into is lead vs overlead. That will more than likely require a maneuver to figure out...I will say however that if your bearing rate is low and your crossed bearings on the geoplot are relatively far away that you are more than likely looking at an overlead, while a lag will have more of a classic "fan" shape with crossed bearings significantly closer. An experienced eye will tell you that a lag simply 'looks different' from an overlead, but it's difficult to qualify in writing. The reason it's better to maneuver is because maneuvering from a lag to an overlead or vice versa will give you a minimum range on one leg and a maximum range on the other, which really helps your solution lock in nicely after only two, maybe three legs on a non-maneuvering contact. The added benefit to a manual Time/Bearing Plot, by the way, is that it can tell you if a non-maneuvering target is opening or closing by showing whether the bearing rate is decreasing or increasing respectively. It will also show you Closest Point of Approach, which is at the point of highest bearing rate.