The observer’s primary goal is to achieve first-round fire for effect. Especially with modern tools, this is a viable strategy, but can be achieved in myriad ways. Sometimes, environmental factors cause the impacts to miss, the FSC’s solution is wrong, or your target location is off. Knowing the distance to target is crucial in any case.
In the absence of laser rangefinders and GPS precision tools, you can still correct range for adjustments using successive bracketing.
With bracketing, you are mathematically guaranteed to be on target upon conclusion. In fact, you can do this using only your eyeballs - no tools (or maths) required. However, it is time-consuming.
Setup
Ensure clear sightlines to your target such that you can see beyond and ahead of it.
Determine the target location as best you can using your preferred means and tools available. All methods of target location are valid for bracketing.
Begin a CFF using the ADJUST FIRE mission.
If DANGER CLOSE or to avoid collateral damage, request SMOKE IN ADJUST, HE IN EFFECT.
Include all necessary methods of control in your CFF such that you can observe the impacts: SPLASH is required.
Principle and Goal
The bracketing method works on geometric convergence: but don’t worry, you are involved in no maths.
When we first observe an impact, whether it is short of the target or behind it, we establish an initial bracket based on the observer-target distance, e.g., 400 metres when the OT distance is greater than 2000 metres.
This means: if the impact was behind it, we DROP 400. If it was in front of it, we ADD 400.
Range Bracketing Guide | |
---|---|
Observer-Target Distance (metres) | Initial Bracket |
0 - 1000 | 100 |
1000 - 2000 | 200 |
>2000 | 400 |
Our goal is to “break the 100-metre bracket” by overcorrecting to the other side of the target. We do this by continuously halving the correction with every subsequent adjustment and alternating ADD/DROP: when you first ADD, next you DROP, and vice versa.
This will alternate the impacts in front and behind the target.
Next, we ADD/DROP 200. Once again, it overcorrects, so if we were in front before, now we are behind and vice versa.
Now we DROP/ADD 100.
Breaking the 100-metre bracket
With this last adjustment, we have “broken” the 100-metre bracket and you will already observe impacts close to target.
The final adjustment from here is, “ADD/DROP 50, FIRE FOR EFFECT, over.”
Because we always halved the distance, we were mathematically guaranteed to converge on 0 error eventually. Whether we begin with 200, 400, 800 or 1600 metres does not matter – the bigger the bracket, the longer it takes, but it will always converge as long as we only ever halve the prior adjustment.
If you guess at any point, your error compounds with subsequent adjustments. In fact, the amount you guess is exactly the amount you move the final impact point forward or back from the target when you’ve finished halving.
Adjust lateral deviation
In principle, you can adjust for lateral deviation, i.e., LEFT or RIGHT, with the same method.
You can also “wait” with your lateral adjustments until you are nearly range-correct, only making gross deviation adjustments along the way.
At this point, you can use binoculars or compass to see the deviation in milliradians and convert it into metres, knowing the distance to your target, using the mil-relation formula.
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