Question: **Clarification**:
I'm looking for an electrical component to use in a device that will sense large physical impacts. When an impact event occurs, all it has to do is pull one line high for around a second. There is no requirement it pull the line back down. 

I do not want this device tied to outputs from my quadcopter in any way. It needs to be standalone. I understand there are beacons with RF signals one can use for the application I describe, but that's not what I want. I just want an isolated impact sensor. :-)

I like the reed switch idea below, but was hoping for something a little more off-the-shelf. I'm going to give this a few more days before I pick one of the provided solutions.

Original Question

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I would like to know when my quadcopter impacts the ground (crashes). I am going to wire up a buzzer or other noisemaker to make it easier to find the crash site.

I've thought about using an `accelerometer` and I've thought about using a [`piezo sensor`](http://en.wikipedia.org/wiki/Piezoelectric_sensor), and I don't know which is better or if there is an even better option out there.

Requirements:

* Pull one pin high for around a second after a crash.
* Be able to survive a small crash and be useful next time around.
* Operate around 5V
* Be small (yeah, I know this is relative. Let's say smaller than 2 inches by 2 inches)
* Be lightweight (yeah, this relative too. Let's say "not heavy.")
* Less then $10 USD

So the question is: what type of impact sensor best fills my needs? I do have questions about what device to use to make a 99db sound, but that will wait for a different question. At the moment I just want a sensor that I can wire up independent of the quadcopter and have it know when a crash has occurred.

Please point me in the right direction.

Answer: 
Since your goal is to find your drone once you have lost it, I would go in the autonomous beacon direction. Relying on the crashed drone battery seems a bit overconfident. Some of those key locator beacons have a pretty impressive range and would fulfill all your requirements, except for price. For instance: 

www.loc8tor.com

www.sticknfind.com
So I've decided to go with an accelerometer after all. I know the question was looking for other answers, but this turned out to be the easiest. The one I got has free-fall detection built into it, so a simple microcontroller should be all I need to talk I2C to it. Thanks for all your suggestions.