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ALC Demolitions Combat Engineer 12B30 ALC phase 1
EXAM ACTUAL EXAM COMPLETE QUESTIONS AND
CORRECT ANSWERS LATEST UPDATE THIS YEAR
SUMMARIZED EXAM COVERAGE (ALC PHASE 1)
The 12B30 ALC Phase 1 Demolitions exam focuses on:
• Demolition theory, explosive types, and effects
• Demolition safety, misfire actions, and QD/MDI planning
• Initiation systems (electric and nonelectric) and circuit troubleshooting
• Demolition calculations (NEW, MSD, time fuse, det cord, resistance)
• Charge construction and placement for steel, timber, concrete, roads, and structures
• Obstacle reduction and breaching fundamentals (SOSRA)
• Mission planning, OPORD integration, and engineer tactical tasks
• ORM application and accountability of explosive materials
1. During demolition planning, your squad leader recommends placing C4 without tamping because it
saves time. What is the most accurate impact of no tamping?
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A. It increases explosive force into the target and improves cutting effectiveness
B. It reduces efficiency because blast energy escapes, requiring more explosive for the same effect
C. It prevents fragmentation, making it safer for Soldiers near the charge
D. It guarantees shaped charge effects without additional construction
Answer: B
Rationale: Untamped charges waste explosive energy outward, reducing effectiveness and increasing
explosive requirement.
2. While preparing a nonelectric firing system, you discover the time fuse is damp and partially
cracked. What is the safest action?
A. Dry it in direct sunlight and use it anyway to prevent mission delay
B. Replace the time fuse immediately because damage can cause unpredictable burn rates or misfire
C. Wrap tape around the damaged area and ignite it carefully
D. Cut off the damaged portion and splice the remaining fuse together
Answer: B
Rationale: Damaged time fuse is unsafe and unreliable, risking misfire or premature detonation.
3. A Soldier wants to test an electric blasting cap circuit by touching the wires to a battery briefly.
What is the best corrective response?
A. Allow it if the battery is small because it cannot initiate a cap
B. Stop the Soldier because unauthorized power sources can cause accidental detonation
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C. Allow it only if the wires are insulated
D. Allow it if the cap is not connected to the main charge
Answer: B
Rationale: Electric caps can be initiated by unintended current sources; only authorized testing devices
are used.
4. During a bridge demolition rehearsal, you identify that the withdrawal route crosses the predicted
fragmentation danger area. What is the best corrective action?
A. Keep the route because fragmentation rarely travels beyond 50 meters
B. Adjust the withdrawal plan and ensure all personnel move outside minimum safe distance before
firing
C. Reduce the explosive amount regardless of target requirements
D. Fire immediately to minimize time exposed to the danger area
Answer: B
Rationale: Withdrawal routes must avoid hazard areas; minimum safe distance must be maintained
before initiation.
5. A team leader asks why detonation velocity matters when selecting explosives for cutting steel.
What is the best explanation?
A. Higher detonation velocity produces greater shattering effect, improving cutting and breaching
performance
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B. Lower detonation velocity always increases brisance and improves cutting performance
C. Detonation velocity affects only smoke production and has no effect on cutting
D. Detonation velocity matters only for low explosives like black powder
Answer: A
Rationale: High detonation velocity increases brisance, which improves cutting and shattering effects.
6. During a deliberate breach, your platoon is following SOSRA and the enemy is firing heavily on the
reduction element. What should occur first?
A. Assault element crosses the obstacle immediately to gain surprise
B. Suppress the enemy to allow reduction forces to operate safely
C. Reduce the obstacle first because suppression wastes ammunition
D. Secure the far side of the obstacle before any action begins
Answer: B
Rationale: SOSRA begins with suppression to protect breach forces and enable reduction operations.
7. While preparing a det cord ring main system, you notice the knot tying the branch line is loose.
What is the most correct action?
A. Leave it because det cord will detonate even with loose knots
B. Retie the knot properly to ensure reliable detonation transfer and prevent misfire
C. Tape over the loose knot and proceed without retie
D. Cut the branch line shorter to increase detonation speed
ALC Demolitions Combat Engineer 12B30 ALC phase 1
EXAM ACTUAL EXAM COMPLETE QUESTIONS AND
CORRECT ANSWERS LATEST UPDATE THIS YEAR
SUMMARIZED EXAM COVERAGE (ALC PHASE 1)
The 12B30 ALC Phase 1 Demolitions exam focuses on:
• Demolition theory, explosive types, and effects
• Demolition safety, misfire actions, and QD/MDI planning
• Initiation systems (electric and nonelectric) and circuit troubleshooting
• Demolition calculations (NEW, MSD, time fuse, det cord, resistance)
• Charge construction and placement for steel, timber, concrete, roads, and structures
• Obstacle reduction and breaching fundamentals (SOSRA)
• Mission planning, OPORD integration, and engineer tactical tasks
• ORM application and accountability of explosive materials
1. During demolition planning, your squad leader recommends placing C4 without tamping because it
saves time. What is the most accurate impact of no tamping?
, Page 2 of 96
A. It increases explosive force into the target and improves cutting effectiveness
B. It reduces efficiency because blast energy escapes, requiring more explosive for the same effect
C. It prevents fragmentation, making it safer for Soldiers near the charge
D. It guarantees shaped charge effects without additional construction
Answer: B
Rationale: Untamped charges waste explosive energy outward, reducing effectiveness and increasing
explosive requirement.
2. While preparing a nonelectric firing system, you discover the time fuse is damp and partially
cracked. What is the safest action?
A. Dry it in direct sunlight and use it anyway to prevent mission delay
B. Replace the time fuse immediately because damage can cause unpredictable burn rates or misfire
C. Wrap tape around the damaged area and ignite it carefully
D. Cut off the damaged portion and splice the remaining fuse together
Answer: B
Rationale: Damaged time fuse is unsafe and unreliable, risking misfire or premature detonation.
3. A Soldier wants to test an electric blasting cap circuit by touching the wires to a battery briefly.
What is the best corrective response?
A. Allow it if the battery is small because it cannot initiate a cap
B. Stop the Soldier because unauthorized power sources can cause accidental detonation
, Page 3 of 96
C. Allow it only if the wires are insulated
D. Allow it if the cap is not connected to the main charge
Answer: B
Rationale: Electric caps can be initiated by unintended current sources; only authorized testing devices
are used.
4. During a bridge demolition rehearsal, you identify that the withdrawal route crosses the predicted
fragmentation danger area. What is the best corrective action?
A. Keep the route because fragmentation rarely travels beyond 50 meters
B. Adjust the withdrawal plan and ensure all personnel move outside minimum safe distance before
firing
C. Reduce the explosive amount regardless of target requirements
D. Fire immediately to minimize time exposed to the danger area
Answer: B
Rationale: Withdrawal routes must avoid hazard areas; minimum safe distance must be maintained
before initiation.
5. A team leader asks why detonation velocity matters when selecting explosives for cutting steel.
What is the best explanation?
A. Higher detonation velocity produces greater shattering effect, improving cutting and breaching
performance
, Page 4 of 96
B. Lower detonation velocity always increases brisance and improves cutting performance
C. Detonation velocity affects only smoke production and has no effect on cutting
D. Detonation velocity matters only for low explosives like black powder
Answer: A
Rationale: High detonation velocity increases brisance, which improves cutting and shattering effects.
6. During a deliberate breach, your platoon is following SOSRA and the enemy is firing heavily on the
reduction element. What should occur first?
A. Assault element crosses the obstacle immediately to gain surprise
B. Suppress the enemy to allow reduction forces to operate safely
C. Reduce the obstacle first because suppression wastes ammunition
D. Secure the far side of the obstacle before any action begins
Answer: B
Rationale: SOSRA begins with suppression to protect breach forces and enable reduction operations.
7. While preparing a det cord ring main system, you notice the knot tying the branch line is loose.
What is the most correct action?
A. Leave it because det cord will detonate even with loose knots
B. Retie the knot properly to ensure reliable detonation transfer and prevent misfire
C. Tape over the loose knot and proceed without retie
D. Cut the branch line shorter to increase detonation speed
