SA-4 Wind Effects

Objectives
1. State where wind information can be obtained for local air-to-surface ranges.
2. State the advantages and disadvantages of the combat offset release aim point (RAP).
3. Calculate a release aim point (RAP) and release aim point extended (RAPE) using the combat offset method.
4. State which method; drifting or crabbing will produce the best manual bombing scores.
5. State what displays and methods are used to compensate for winds using CCIP bombing.
6. Describe corrections made throughout the pattern for winds.
Assignment
1. Review Lesson SA–4, Wind Effects, in the Surface Attack student guide, B/F-V5A-K-SA-SG.
2. Review MCMAN 11-238 Vol 2, Section 4.5, Wind Effects.
3. Complete SA–4 review exercise.
Information
Wind Analysis
Objective 1 — State where wind information can be obtained for local air-to-surface ranges.
1. Winds
a. The winds that affect your aircraft during the final delivery of your bomb are of primary importance to
accurate bombing. For CCIP bombing, the computer takes into account the winds. It is still important to
understand what the wind is doing to the aircraft and the weapon once it is released from the aircraft. Moreover,
wind affects your ground track throughout the pattern and must be taken into consideration in order to arrive at
planned parameters. The following discussion, as it relates to the bombing pass essentially explains what the CCIP
computer is doing to compensate for winds.
b. Current winds at the target area aid in the targeting solution and should be obtained from the base weather
shop, internet web sites such as the Air Force Weather Agency (AFWA) site, or call the range for preflight wind
planning. While airborne, look for smoke, blowing dust, and the EGI information presented on the MFD.
c. As the aircraft travels through one air mass into another with a different velocity or direction, it takes time for
it to become affected and move with the wind. Aircraft drift acceptance rates vary with air density, aircraft mass,
aircraft shape, etc. The acceptance rate for most tactical aircraft is two to five seconds. Therefore, the wind used
to compute the release aim–point (RAP) is the wind two to five seconds prior to release. A wind shear below
release altitude has very little effect on bomb range and bomb track. Two to five seconds equates to a point (in
altitude) back up the dive flight path of your aircraft, (the steeper your dive angle, the greater the altitude lost per
second).
2. Wind assumptions:
a. You must consider the wind when planning for each manual bombing event and remember wind affects your
aircraft throughout the entire pattern plus the bomb at release. During this discussion of wind effects and
corrections, make the following assumptions:
(1) The bomb being released is low-drag fin-stabilized and is released in coordinated flight.
(2) The air mass has a constant direction and velocity from the surface to infinity.

centerline requires additional, although usually minor, corrections.
(4) The aircraft maintains a constant heading and velocity after release. This isn’t necessary and doesn’t
affect the accuracy of the bomb, but it does show the relationship between the aircraft flight path vector and
the vector of the bomb.
(5) There are no pilot induced errors involved with the release of the bomb.
(6) Aircraft time on final from roll–out to release is approximately equal to the bomb TOF.
3. Wind effects for manual bombing.
a. For an aircraft flying in level, unaccelerated, flight
with no wind, a bomb will fall vertically below the
aircraft from release until it hits the ground. In order to
hit a given target, you must fly over it. If the run-in
heading is varied while all other parameters remain the
same, the bomb TOF and bomb range will remain the
same. Hence, there are an infinite number of release
points around any target for a given set of parameters.
These release points will form a circle around the target
that is equal to bomb range (Figure 4-1).
b. Now suppose the same release condition exists,
except the air mass is moving. The air mass simply
moves across the ground and everything that happens
within it remains exactly the same. The bomb is only
“aware” of the aircraft’s heading and true airspeed
(TAS); it can’t detect the movement of the air mass.
When released, the bomb will fall vertically below and
in trail with the aircraft until impact. The horizontal
distance traveled in relation to the air mass will remain
the same. Because the bomb and the aircraft are drifting
with the wind, the bomb impact point will move
downwind (Figure 4-2).
c. With a constant wind velocity and TOF, the bomb
impact point can be computed regardless of run-in
heading. To compute the miss distance, use the
formula: miss distance (D) = V x TOF x 1.69
Example: Velocity = 35 knots, TOF = 7.1 seconds
D = 35 x 7.1 x 1.69 = 419.9 feet
4. Wind corrections
a. Any time wind enters the picture, an “upwind aim
point” or release aim point must be taken into account.
In a no-wind situation the target is the RAP.
b. The distance arrived at in the above example is the
downwind miss distance. To hit the target, aim into the

wind a distance equal to miss distance. This new aim
point is the upwind aim point or the RAP and is good
for any run-in heading. The formula for computing the
RAP is the same as the miss distance formula. These
correction factors are nothing more than bomb TOF
multiplied by 1.69. To compute a RAP with this
crosswind correction factor, simply multiply the wind
velocity by the given factor.

c. To hit the target, the manual pipper must be on the
RAP and all parameters (dive angle, altitude, airspeed,
and G loading) must be met at the time of release. This
holds true for any run-in heading; the RAP remains the
same. There are still an infinite number of release points
around any RAP for any given release parameter. With
CCIP bombing the pipper will be on the target but the
aircraft will be steered upwind to compensate for the
wind.
d. The most common method for computing a manual
wind-corrected RAP is knows as Combat Offset.
Combat Offset
Objective 2 — State the advantages and disadvantages of the
combat offset release aim point (RAP).
Objective 3 — Calculate a release aim point (RAP), release
aim point extended (RAPE) using the combat offset method.
1. Combat Offset
a. To arrive at release parameters with the manual
pipper on the RAP, aircraft drift on final must be taken
into account. Use the same formula to compute a new upwind roll-out point or a release aim point-extended
(RAPE). Assuming that time on final and bomb TOF are the same the distance from target to the RAP is equal to
the distance from the RAP to the RAPE (Figure 4–3).
b. Because of winds and aircraft drift, the original Aim Off Point (AOP) is no longer valid. A wind-corrected
AOP or an Adjusted AOP (AAOP) must be computed. To have an upwind roll-out reference other than the RAP
and RAPE draw a line from the no-wind AOP into the wind and a line 12 o’clock to the RAPE. Where the two
lines meet is the new roll-out reference point or the AAOP.
2. Example of combat offset calculation: (Refer to Figure 4-4, Bomb Table Extract)
30° DB, 3500’ AGL release altitude, 460 KTAS, Winds 050/35
Crosswind correction factor = 12 ft/kt
12 ft times 35 = RAP
RAP = 420’ at 2 o’clock (approximately, assume 360° run–in)
RAPE = RAP time 2 or 840 ft

3. Advantages of combat offset
a. This method is quick and requires only one mathematical calculation.
b. One RAP is good for all run-in headings.
4. Disadvantages of combat offset
a. Estimation of offset distances during high wind conditions or long bomb TOFs is difficult.
b. RAP azimuth estimation is sometimes difficult, especially at low dive angles. This is very critical with long
offset distances.
Crosswind Correction Techniques
Objective 4 — State which method; drifting or crabbing will produce the best bombing scores.
1. While on final, there are two methods of counteracting crosswinds. The aircraft may be allowed to fully drift with
the wind or the aircraft may be flown in a crab to negate aircraft drift. Up to now the discussion has covered only a
fully drifting aircraft. Fully drifting techniques are used for higher dive angles because drift across the ground is
difficult to see. During level and low angle events aircraft drift across the ground is readily apparent. Therefore,
crabbing the aircraft similar to landing in a crosswind is the solution.
2. Because of bomb trail (horizontal distance from aircraft to bomb impact point) and bomb drift, the aircraft’s
ground track must be displaced upwind. The relatively small bomb drift of low drag ordnance requires shifting the
ground track only a few feet upwind. In fact, for low drag weapons, a ground track that passes over the target will
cause a relatively insignificant downwind error. The opposite is true of high drag (HD) ordnance.
3. Keep in mind that for the fighter pilot looking through the manual bombsight, pipper track will look the same
whether the aircraft is fully drifting or crabbing. The only significant difference is in the aircraft’s ground track as it
approaches release. In both cases, the aircraft essentially crosses directly over the target.
CCIP Wind Corrections
Objective 5 — State what displays and methods are used to compensate for winds using CCIP bombing.
1. HUD CCIP Display
a. A crosswind is indicated on the HUD CCIP display by displacement of the pitch ladder and FPM from center
(DRF mode) and the angle of the bomb fall line (BFL). The flight path marker (FPM) is placed to maintain the
BFL on the target which is essentially the crab method of manual crosswind corrections.
b. In a no–wind situation the FPM or (AOP) would be directly above the target and displaced approximately
40% of the BFL length.
c. In a crosswind, the boresight cross should be just long of the AAOP and FPM on/near the wind adjusted AOP.
Note: For CCRP deliveries (level run–in with a climb/toss release) in a crosswind, the Azimuth Steering Line (ASL)
will be upwind of the target/TD Box. Flying the FPM along the ASL is essentially a crab–type crosswind correction.
2. Wind Corrections
The overall goal is to make each bombing pass better than the one before it. As a technique, on the first pass aim
directly at the target. On the second pattern make corrections based on the first pass. Add a correction factor that is
approximately ½ to ⅔ of error amount from the first pass.
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Pattern Adjustment For Wind
Objective 6 — Describe corrections made throughout the pattern for winds.
1. Pattern considerations
a. The point at which you start the roll-in will usually have to be shifted in the same direction as the RAP and by
a considerably longer distance, because the wind affects you throughout the roll–in maneuver. Try to picture your
AAOP and fly towards it, not the target.
b. For headwinds on final, move your base leg distance “in” and crab to hold it.
c. For tailwinds on final, move your base leg distance “out” and crab to hold it.
d. For crosswinds on final, delay or advance your roll-in.
2. Quartering winds
a. Base-leg altitude winds may vary from release altitude winds and your roll-in point will have to be adjusted
accordingly.
b. Quartering winds will require various combinations of the above. Compensation for winds involves the
simultaneous application of both crosswind and range wind (head/tail) corrections.
Summary
1. Wind Analysis
2. Combat Offset
3. Crosswind correction Techniques
4. CCIP Wind Correction
5. Pattern Adjustments for Winds
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Review Exercise SA–4
Complete the following review exercise by choosing the correct responses. Answers are in Attachment 1.
1. Combat Offset RAP
a. Procedures: Full wind velocity (knots) times ____________ correction factor (feet/knots).
b. Strengths:
• RAP and ____________ are good for any attack axis/run-in heading.
• It is quick and easy to calculate.
• With unknown winds, it can be applied after observing first pass impact point.
c. Weaknesses:
• Sometimes hard to visualize distances from target, especially on ____________ angle events (only the 3-9
line remains constant).
• RAP azimuth estimation is sometimes difficult, especially at low dive angles.
Compensating for Wind on Final (from roll out to release)
2. Fully Drifting method:
a. Characteristics: roll–out upwind of target on run–in heading, aircraft drifts downwind, generally used in
____________ angle deliveries.
b. Procedures:
• Find RAPE — ____________ times extension of RAP (if aircraft time on final roughly equals bomb TOF,
RAPE is two times the RAP).
• AAOP = AOD at 12 o’clock to the ____________.
• Lead roll–in so as to pull aircraft toward AAOP, roll–out on planned run–in heading, set IPP from RAPE,
let aircraft drift (pipper drifts to RAP).
• Pickle with parameters met and pipper on ____________.
3. Crab method:
a. Characteristics: fly up run-in line across target with enough crab into wind to hold ground track. Commonly
used for level or ____________ angle deliveries (easy to see actual track along ground).
b. Procedures:
• RAP and RAPE are about the same as for fully drifting.
• Lead the roll–in so as to roll–out over run–in line, roll–out with crab to hold ground track across target,
you should perceive aircraft AOP (but flight path reference should be pointed at AAOP and pipper set
short of RAPE), pipper will drift toward RAP.
• Pickle with parameters met and manual pipper on _________________ .