I know nothing about the military, so I apologize if this is obvious. Why is this practical?

CRUSHER: I recommend we evacuate and seal off all non-operational areas, and group the families and crew on the odd-numbered decks.

Booby Trap


The ship is experiencing a rapid energy drain and is operating on reserve power. Since we know that a very sizeable chunk of the ship's energy output is channelled into keeping the crew alive (59.2%?), taking out half of the ship's decks would result in a dramatic lowering of their energy needs and usage for heating, gravity control, lighting, life-support, etc and hence increase the length of time that the shields can remain up.

GEORDI: With the engines idling, the energy loss has been limited. But our reserves will be depleted in less than three hours. We won't be able to hold our shields in place.

As to why they have them move to the odd-numbered decks (rather than having them all cluster in the centre of the ship, for example) one assumes this is because a) Now only half the ship's crew have to move at all b) The half that have to move only have to move up or down one deck, minimising turbolift use.

(h/t to ApproachingDarknessFish)

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    @EikePierstorff By using odd-numbered decks, half the crew doesn't need to move, and the other half only needs to move one level. In order to use, for example, the upper half of the ship, half the crew doesn't move, and the other half has to move on average about 10 levels. – ApproachingDarknessFish Nov 13 '18 at 8:26
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    the life-support requirements should more depend on the number of lifes, not on living space. everything exept gravity at least. – ths Nov 13 '18 at 12:14
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    @ths - Actually it's not entirely clear why a) Why life-support takes such a colossal amount of power and b) Why when life support shuts down every starts choking instantly instead of just breathing the available hour for several hours. Chalk it down to the need to inject urgency into a scene. – Valorum Nov 13 '18 at 12:33
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    @user20310 dissipating body heat depends obviously on #bodies. (in space, you don't need heating) – ths Nov 13 '18 at 12:42
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    @Valorum That number may also include gravity plating and heating – Izkata Nov 13 '18 at 19:20

Using odd numbered decks is simple, convenient, and easy to communicate.

The key point here is to reduce the number of occupied decks. By specifying odd-numbered decks, people only have to move one deck up or down. Only the people on even-numbered decks have to move at all and it is easy for people to verify for themselves that they have moved to a safe deck. This simplicity should make the evacuation process easier and reduce the risk of anybody being on an unsafe deck by mistake. If you add the additional instruction that people on even-numbered decks move one deck up, then everybody is moving in the same direction.

It is a bit like the problem of separating a group of people into two equal sized sub-groups. If you just say get into pairs, they will take forever. If you line them up and give them each a number, it is much easier to divide them up as you wish.


One good reason would be to minimise risk if the situation escalates further.

Escape pods are evenly distributed across the ship.

Getting people onto even-numbered decks means that if they need to evacuate, then people can get to the escape pods quickly and efficiently, and with minimal overcrowding.

On the other hand, if everyone is moved to the upper decks and you need to evacuate, the escape pods on the lower decks would go unused and the ones on the upper deck would be overcrowded.

  • Putting everyone on the upper half of the ship doesn't overcrowd the decks any more than putting everyone on odd numbered decks. In the the first case, the lower deck escape pods go unused; in the latter, the even deck escape pods go unused. Either way, the escape pod capacity needs to be double the ship population. – Nuclear Wang Nov 13 '18 at 15:23
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    @NuclearWang but if you assume escape pods on every deck with some surplus capacity but not huge amounts, people are 0-1 decks from a pod in one situation, while in the other some of them may be half a ship away – Chris H Nov 13 '18 at 15:41
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    @NuclearWang - if everyone is on even decks, they can get to the pod on the adjacent decks reasonably quickly; even in the worst case, if the turbolifts are inactive, the next deck is only a short jeffries tube away so if the pods on the deck you're on are full, then you still have options. If everyone if on upper decks, the pods on the lowest decks can't be accessed in a timely manner at all by anyone; you don't have another in an emergency option if the pod is full. – Spudley Nov 13 '18 at 15:43
  • My understanding is that they basically shut down the decks not in use. Once you've sealed off the unused decks, you can't access the escape pods from there anyway. Not much of a "seal" otherwise. – Nuclear Wang Nov 13 '18 at 15:57
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    @einpoklum - The ship also has emergency transporters situated all over the ship including in the centre of the saucer section – Valorum Nov 13 '18 at 16:29

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