The March Column and the Water Ration
A training march of 24 candidates and 2 instructors must cover 18 km on a dirt road in the Angolan interior. Each person carries a 2-litre personal water bottle, and the column has two 20-litre jerrycans in a support vehicle. The plan allows 0.5 litres per person per hour of marching, and the expected pace is 4 km/h including a 10-minute rest each hour. Mid-morning temperature is forecast at 34 °C. One candidate, who has been vomiting since the previous evening, asks to march anyway because he does not want to lose his place in the course.
1. Calculate the total march time and the total water requirement, then compare it with the water carried.
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Pure marching time = 18 / 4 = 4.5 hours.
With a 10-minute rest per hour, the column needs roughly 4 full rest stops (after hours 1, 2, 3, 4), adding about 40 minutes, so total elapsed time ≈ 5 h 10 min. Using 5 hours of counted marching time for the ration:
- Requirement = 26 people × 0.5 L/h × 5 h = 65 litres.
- Carried = (26 × 2 L) + (2 × 20 L) = 52 + 40 = 92 litres.
So the plan is feasible with a margin of about 27 litres. That margin is the safety reserve and should not be spent on non-essential uses.
2. The vomiting candidate insists on marching. Give the correct decision and the reasoning behind it.
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He should be withheld from the march and referred for medical assessment.
Reasoning: vomiting since the previous evening means he is already likely volume-depleted before the march begins. At 34 °C, with 0.5 L/h as the planning figure for a healthy person, a dehydrated candidate will deteriorate faster, risks heat injury, and becomes a casualty the column must then carry - endangering the whole group. His personal wish not to lose his place is not a medical or command criterion. The correct answer is not 'let him try and see' but 'remove the risk, document it, and let the medical chain decide when he returns'.
3. Halfway through, the support vehicle breaks down and the jerrycans cannot be carried. What is the soundest adjustment?
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Recalculate against the personal bottles only: 26 × 2 L = 52 litres for a requirement of 65 litres - a shortfall of about 13 litres, i.e. roughly 26 %.
Sound adjustments, in order of preference: (1) shorten or halt the march and return by the shortest route; (2) reduce pace and rest in shade during the hottest hours; (3) ration explicitly and evenly, never allowing individuals to drink their whole bottle early. What must not happen is continuing the original plan while pretending the water is still there. The judgement being tested is that a plan is only valid while its assumptions hold, and the commander must re-plan the moment a constraint changes.