KDF Fire Correction

Correction

Shot 1

Line –m

Range –m

Enter all three positions to get a correction.

Gun position

Where the battery is firing from

Lat

Lon

Grid

Target

The point you want to hit

Lat

Lon

Grid

FOS

Fall of shot

Where the round actually landed

Lat

Lon

Grid

Terrain slope (optional)

Gunm

Targetm

Slope from gun to target –

Enter both elevations to work out the slope.

Angular deviation –

Radio callout

Waiting for positions

Leg	Distance	Bearing
Gun → Target	–	–
Gun → Fall of shot	–	–
Target → Fall of shot	–	–
Fall of shot → Target	back bearing	–

Markers are locked so they can't be moved by accident. Tap Lock to unlock, then drag to move. Twist two fingers to rotate, or slide them up or down to tilt.

Line –m

Range –m

Shot 1

Gun position

Target

Fall of shot

Gun position

Target

Fall of shot

Gun to target

Gun to fall of shot

Target to fall of shot

Correction (line and range)

Right angle

Bearings read from the gun, and from the target to the fall of shot. Arrows show where the next round must move.

Area to save

Save area for offline use

Move and zoom the map so the box covers the area you need.

Map styles

Detail

Streets

Starting...

Now

Enter positions on the calculator to see them here.

Flight weather

Choose a location to see the forecast.

Hour by hour Tap an hour for details

Wind by height

Your drone

Flight height

Wind units

Limits

7-day outlook

Sun & light

Forecast: Open-Meteo. Kp index: NOAA SWPC. Models are estimates, so always check conditions on site before launch.

My mission log

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Map & Tactical Display Enabled

Imaginary right-angled triangle

Shows the right-angled correction triangle (Line & Range legs) between Target and Fall of Shot. Direct distances between all positions are always retained.

Visible on tactical map

Needs attention

Imaginary right-angled triangle

Visualizes line and range shift as perpendicular legs between Target and Fall of Shot. Direct distances between all positions are always retained.

Visible on tactical map

No one has shared a location yet.

How it works

The calculator turns the three positions into flat distances on the ground, using a mean Earth radius of R = 6,371,000 m. It then compares where the round landed with where you wanted it.

Ground offsets between two points

North-south and east-west distance, in metres.

ΔN = rad(lat₂ − lat₁) × R
ΔE = rad(lon₂ − lon₁) × R × cos(rad((lat₁ + lat₂) / 2))

Distance and bearing

Bearing is measured clockwise from north.

Distance = √(ΔN² + ΔE²)
Bearing  = atan2(ΔE, ΔN)  (0° to 360°)

The correction v1

Line says which way to swing. Range says whether to lengthen or shorten.

Line   = LEFT if bearing(Gun→FOS) > bearing(Gun→Target), else RIGHT
Range  = ADD if distance(Gun→FOS) < distance(Gun→Target), else DROP

Line shift  = | d(Target→FOS) × sin(360° − bearing(Target→FOS)) |
Range shift = | d(Target→FOS) × cos(360° − bearing(Target→FOS)) |

The correction v2

The miss is measured against the gun's line of fire. Line is the miss across that line, range is the miss along it.

θ = bearing(Target→FOS) − bearing(Gun→Target)

Line shift  = | d(Target→FOS) × sin(θ) |
Range shift = | d(Target→FOS) × cos(θ) |

Line   = LEFT if d × sin(θ) > 0 (landed right), else RIGHT
Range  = DROP if d × cos(θ) > 0 (landed beyond), else ADD

Units

A full circle is 360° or 6,400 NATO mils, so 1° = 17.78 mils. Distances are rounded to the nearest metre.

Fire Correction

Fire Correction

Gun position

Target

Fall of shot

Flight weather

My mission log

Admin

Imaginary right-angled triangle

Imaginary right-angled triangle

How it works

Ground offsets between two points

Distance and bearing

The correction v1

The correction v2

Units

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Map layers

World clock