Why does Bill Cage wake up in the helicopter?

It's because the time loop works for roughly 24 hours. As Rita said, the Omega would 'reset the day', which meant roughly 1 day prior would be as far back as the Alpha/Cage would go. Cage's day before the invasion goes roughly like this:

1. Wakes up in the early morning on helicopter. Meets General, gets tazed.
2. A few hours pass.
3. Cage wakes up in the mid to late morning. This is where the time loops reset to throughout the film.
4. Day of training on the military base.
5. Day ends.

The next day, the invasion occurs. During that day, they wake up, get in gear, and ship out; hours would have passed during all that. Then Cage manages to kill the Alpha, and get its blood mixed with his own. This must have happened 24 hours after step 2 above, during the hours that Cage was out. Alternatively, it happened to occur exactly 24 hours after step 3, but the hours of him unconscious provides a nice window where if time is reset he wouldn't be able to alter his fate of being sent on the invasion.

Now, why did he go back to earlier when the Omega was destroyed? I offer these two assumptions:

1. Omega blood functions the same way as Alpha blood.
2. The time reset is still only 24 hours.

We don't know that 1 is true, as no one in-universe knows this. 2, is able to be true while still enabling what we see in the film. The attack on the Louvre occurs earlier in the day than the invasion. During the attack on the Louvre, it's still dark out. J squad had been recruited for this mission during Step 4 above, the day of training. They then get convinced to go, and head out. They arrive during the evening/early-morning. The mission is a success, and the Omega is defeated. This would have happened 24 hours after a point in time prior to Step 1 above, while he was asleep on the helicopter. It would have triggered the start of a new time loop from that point it time.

Ergo, Cage was sent back 24 hours prior to when the Omega was killed, which means he wakes up in the helicopter.

Possibly because the effect of resetting caused by an omega is bigger than the effect caused by an alpha.

In the original explanation of the time resetting effect Cage is told that the effect is only triggered by the blood of an alpha when it is killed. Alphas are very rare (like every 1 in 6 million creatures are of this leadership caste). When they die it is a sign that the human enemy has done too well in the battle and the day needs to be refought to counter the threat.

There is only one omega. We are not told (and probably can't know because of their uniqueness) what powers the omega actually has. But it doesn't seem unreasonable that, whatever it is, it is more powerful than an alpha. So, perhaps, on its death its blood has a bigger effect on time.

And it makes a hollywood-friendly ending where the heroes don't die (though that might have made a more satisfying story where gain comes from sacrifice not just luck.)

Alternative and simpler explanation: perhaps the reset is triggered earlier in the day

Reading some of the other answers and pondering the situation after watching the movie again, I came up with another explanation: there isn't actually anything to explain.

The time reset seems to be for a fixed period, at least approximately. (It can't be exact as cage dies later and later during the day of the invasion but always seems to return to the same point.) Whether it is merely triggered by the death of an alpha may be irrelevant. In the end the exact same effect is triggered by the death of the omega. But the death of the omega occurs much earlier in the day than the repeated deaths Cage experiences on the beach. So the exact same effect results in Cage waking earlier in his day and, therefore, in the helicopter.

The point is that, when Cage realises he has lost his power, he sets off much earlier in the day to do battle with the omega. It is the middle of the night when the team steal the flyer and it is still night when the omega is killed. So this seat (and the resulting time reset) occur a good few hours before the repeated deaths on the beach or deeper in France. So it makes some sort of sense that Cage is reset to earlier in his day when the time rest from the death of the omega is triggered.

This requires far fewer additional assumptions than the "omega has more power" explanation. It still has holes, but this is weird SciFi not a rigorous paper in mathematical logic so perhaps we should not try to overanalyse it.

my guess is that Cage usually wakes up to the last moment where he regained consciousness. Since he lost consciousness when he was tasered, that's where he wakes up. Now, when Omega is killed, the war is over, so Cage would never have met with the General, and therefore never would have been tasered and lose consciousness. In this situation, the last moment where he regained consciousness is no longer the taser moment, but the nap moment in the helicopter.

How about this theory? I think it's a bit different to and might be hard to understand, based on how we perceive the story as a linear movie:

After watching the movie, I still wondered how one or more entities would be able to somehow alter time in the whole universe to create the resets. A bit like The Butterfly Effect? Nah, didn't really make any sense to me.

But then I've had the idea to understand the resets in a different way:

The Mimics aren't able to time travel or reset time in any way. However, they're able to somehow transfer knowledge/memories back in time utilizing something in their blood.

While watching the movie, we always notice Cage waking up, obviously shocked by the death he experienced just moments ago. But what if he just got that memory that very moment (or just before) similar to how dreaming works. If you've ever wondered why you always wake up after a dream, it's primarily due to you remembering only the dreams right before waking up; even if some time has passed since then.

Now combine this with a video game's "save logic" and you'll get a pretty interesting (and in my opinion conclusive) solution:

• Similar to a gamer, the Mimics being able to transfer memories to "save" at a specific point in time so they're able to transfer back whatever they've learned.

• By default, Alphas would obviously imprint that moment in time to pretty much always be 24 hours before, offering enough reaction time without making it overly complicated (too much to remember).

• The moment Cage kills the Alpha for the "first" time, he gets in contact with the blood, sending back his memories as well (which would obviously alter his own blood in some way as well).

• Cage lacks the knowledge or ability to "reprogram" the alien cells or elements within his blood, so he has no way to alter the point to which his memories are sent back.

• He loses the ability due to blood loss/transfers, simply due to the fact that the ratio/amount would be lowered significantly.

• The Omega obviously created its own save point, but at an earlier point (explaining the time difference for the last "jump").

• Once the omega is killed, memories are sent back to that morning. This happened before, they're talking about the Omega allowing them to kill it.

So the only question this doesn't answer: Why is the Omega gone after the last "jump cut"? Did it retreat or hide, since it knew the humans now possess the knowledge of how their "mind trick" works (even if it's just speculation)?

In case anyone is interested, as far as I've heard, the whole "transfer information back in time" might indeed be possible. Utilizing quantum entanglement you're able to link two or more particles, so both share the same state. While I don't really know all the little details etc. as far as I've heard, you should in theory be able to influence one particle and the second one would mimic (pun here?) this, no matter what/where. (The Mass Effect trilogy also utilizes this and uses it for its faster-than-light communication system.)

So advance this a bit: Relativity theory states that time passes at different speeds based on the objects own speed/mass. So if you move both particles indepently at different speeds etc. time for one of them would pass faster, essentially creating a link between two points in time.

So what if the Mimics are able to utilize this in some way or another as well? This still doesn't explain how the blood/infection gets back in time, but it sounds really interesting, doesn't it?

Alpha death is just an autonomic response for a day reset, but I think the Omega blood gave Cage the ability to DECIDE when to wake up. He subconsciously wanted to wake up earlier than being handcuffed at the base, so he woke up in the helicopter.

When the Omega resets time everything returns to how it was -- except the memories of the alphas. I think this is because the Omega travels back in time to replace the previous version of itself, and then sends the memories out to the reset alphas (or Cage).

SO, when Cage kills the Omega he wants to wake up in the helicopter, so he does. And the Omega replaces its living self with its freshly dead self - disabling all the mimics in the reset day.

That's how I understood it.

Based on the other answers I came to the conclusion that when cage killed Alpha it set a spawn point for him that was placed 24 hours prior to Alpha's death. In other words he respawns at the military base. Later on he loses the ability, but regains it after killing Omega. This event sets a new spawn point which is 24 hours prior to Omega's death. Since he managed to kill Omega earlier during the day than he killed Alpha, his spawn point is also earlier. In other words he wakes up in the helicopter.

This leaves some problems. If Alpha had this time-loop ability, wouldn't Omega have it as well and be alive after the reset? And if it was just Omega which had the ability (and let both Cage and Alpha travel in time), wouldn't killing Omega prevent Cage from going back in time at the end of the movie? The only answer I can think of would be, that the Omega send Cage back in time for the last time when it was still dying. So after the last respawn in helicopter Cage does not possess the time travel ability anymore.

But this leads to another question, if it was Omega which controlled the time travel, why couldn't it prevent Cage from respawning? If we assume it was because he had Alpha's blood, then one might start to wonder why did he gain the ability again from coming in contact with Omega's blood? I mean clearly Omega couldn't time jump itself, which allowed to have it die once and for all. But that would also suggest that coming in contact with it's blood should have no effect...

The other answer would be. The authors needed a happy ending and it wouldn't work otherwise. Meaning, the authors expected people not to care too much about the little details.

How about this explanation:

It is Omega that resets the time, not Cage. It does so automatically, reflexively, in response to Alpha's death. Now that Cage has acquired this "link" with Omega, it's his death that triggers Omega's reflex.

The time to reset to might not be a simple "X hours back" rule, but is set by Omega to a point sufficiently back from the start of Operation Downfall, to allow it to deploy drones - spawn (assumption), spread and dig in - before the battle begins. The start of operation is set by military; Omega is super efficient, taking the exact amount of time, every time, to prepare. Hence, Cage finds himself back at the same point in time at every reset.

Omega resets the time when it dies itself, as well. Again, this happens automatically. The point in time in this case would be prior to the appearing of Omega in it's location in Paris.

We were shown Omega's blood seeping into Cage, not to explain that Cage acquired the ability to reset time, but to establish a reference point for a sequel, which might look like this:

Cage and Rita are both retired from military. Having Omega's blood in him, Cage is linked to, and has visions of, other Omegas floating in space, or perhaps a Super-Omega somewhere on it's base. He tries to warn the authorities, ends up being zapped by police or guards, wakes up on a dissection table, just in time to intercept the surgeon's hand holding the bone saw. He must now escape the psych facility, reunite with Rita, convince a new crew to follow him, break into a military base, hijack a spacecraft, and destroy the Omega/Super-Omega base.

My guess is that time reset is triggered when an Alpha or Cage (with Alpha blood) dies. Time will always be reset to a certain "spawn point". Spawn point for time loop is set to 24 hours prior to the time of "infection" with blood/time of first death upon gaining the time loop ability (which is in both cases the same). The omega did not prevent its down death because it never had the ability. It's the alpha's death that would have triggered a reset.

It is because Cage is taken back in time not in accordance with himself but with the Omega. So, when the Omega dies, the blood gets on Cage, but the Omega was changing time from the beginning of Operation Downfall, where Cage threatens the General. So, it reset time from where the Omega was changing it, not Cage.

Lots of complicated theories...

1) We know very little about how the alien technology works, including time travel. We just have a limited set of observations.

2) We have no observations of, or reason to have any understanding of how an omega's death will affect time.

As such, Cage is sent back as he is because that is what we observe. Our observations do indicate that the mixing of blood with the Omega is a likely factor.

• Omega's blood was seeping into Cage, which allows cage to reset the day right from the beginning.
• Everything that happened before Cage got down the helicopter could not happen because Omega died and the situation will change when Omega dies.
• Fact: When something dies by e.g guns or grenades, blood will seep out from the wound.
• For Omega's blood, it seeped through Cage.
• Fact: When blood seeps out of something in water, it will spread and the water will be mixed with the blood, diluting the blood and at the same time, changing into "blood water".
• The Omega was submerged in water when Cage killed it, so the blood is obviously able to seep into Cage again because he died in the water too when he killed the Omega, meaning that he was in the water too when the Omega's blood was able to seep through him.
• after he reset the day in London again, he saw a crowd at the TV in the office, saying that Omega has been killed, which can mean the Omega died before it could reset the day, the blood of Omega was already transferring to Cage because he is underwater, so he can reset the day without having the Omega alive.

No reputation for comments. Before you start making conclusions, there needs to be agreement on assumptions. The most important being how Cage is traveling back in time.

My interpretation is that the Omega still retains its power to reset, it was not lost as some have claimed. When Cage died the first time, his blood mixed with the Alphas and he was reset along with the Omega. Now every time Cage dies, he is treated as an Alpha trigger to the Omega. The Omega does not seem to be able to remove him from the system remotely. Cage was not actively resetting, just being brought along for the ride. The system was treating his death as the death of an Alpha. Remember, the doctor claimed it was a single organism. You can think of the drones as useless cells of organs that regenerate all the time such as the skin. The Alphas would be vital organs. Death of a vital organ triggers the entire body to reset. The Omega would be the brain.

My conclusion is based on the previous assumption. Since Cage is going along for the ride, if the Omega is dead, then there would be no ride. This would suggest the Omega cannot reset itself or else the movie would not make sense. The reset must be triggered by an Alpha death. This could be a design flaw and not an evolutionary hiccup. This would also suggest the Omega blood is different. By fusing with the Omega blood, he can reset himself.

The mechanics of the reset is a different issue. It is probably based on a dormant anchor that could be related to a 24 cycle or a subconscious cue.

The 24 hour period would be illogical because this is an Alien organism/cyborg. The 24 hour day cycle is from our planet and solar system.

This leaves the subconscious anchor. He wakes up from every reset. Perhaps, his previous consciousness can only be uploaded to a pliable brain. An unconscious brain would probably be considered pliable. The issue with this is he sleeps the night before the fight. He is also unconscious then. This is why I suggested an unconscious cue. He probably relates that specific moment as the beginning of his death. This would also suggest there is some feedback between Cage and the Omega. With the Omega dead, Cage was in full control. He reset himself to the day before to another unconscious state, the helicopter.

I believe that it puts him in a universe where he wouldn't have been tased in the first place, thus placing him where he WOULD have woken up, in the helicopter.