# Why aren't airliner "black boxes" designed to float? **URL:** \ **Category:** Factual Questions\ **Created:** [June 17, 2009, 3:07pm UTC](https://boards.straightdope.com/t/why-arent-airliner-black-boxes-designed-to-float/500073 "2009-06-17T15:07:10Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![Spiff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/spiff/32/9852_2.png) [@Spiff](https://boards.straightdope.com/u/Spiff)\ **Post date:** [June 17, 2009, 3:07pm UTC](https://boards.straightdope.com/t/why-arent-airliner-black-boxes-designed-to-float/500073/1 "2009-06-17T15:07:10Z")
Air France flight 447 goes down in the Atlantic, and the race is on to recover the “black box” flight and voice recorder. The box has a battery that can power a signal (a “ping”) for about 30 days. This particular black box is probably in very deep water, and no one knows exactly where the plane crashed. For these reasons, the data/voice recorder may not ever be recovered. So, why don’t engineers rig these boxes with a sensor, an inflatable baloon, and a canister of compressed air (or CO2, or whatever)? The sensor would only trigger the canister to open and fill up the baloon when it’s been exposed to water and high pressure (say, the pressure at 1,000 feet underwater). Maybe the sensor would only trigger the deployment after detecting these conditions for, say, a week – just to be on the safe side. And voila! The black box floats to the surface and it’s easily collected by Joe Recovery Worker who scoops it out of the water. Why is this not part of the design? ---
**Author:** ![Telemark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/telemark/32/372_2.png) [@Telemark](https://boards.straightdope.com/u/Telemark)\ **Post date:** [June 17, 2009, 3:13pm UTC](https://boards.straightdope.com/t/why-arent-airliner-black-boxes-designed-to-float/500073/2 "2009-06-17T15:13:58Z")
We just did this in another thread. The answers against it were added complexity, damage from the crash would damage any flotation devices, the fact that black boxes are bolted to heavy pieces of metal, danger of premature deployment, and there’s really not much need since this so rarely happens. ---
**Author:** ![firstname](https://avatars.discourse-cdn.com/v4/letter/f/7ab992/32.png) [@firstname](https://boards.straightdope.com/u/firstname)\ **Post date:** [June 17, 2009, 3:17pm UTC](https://boards.straightdope.com/t/why-arent-airliner-black-boxes-designed-to-float/500073/3 "2009-06-17T15:17:48Z")
Also, in the other thread it was mentioned that most plane crashes happen over land, so this would be useless in most situations when its needed. ---
**Author:** ![The\_Great\_Philosopher](https://avatars.discourse-cdn.com/v4/letter/t/3ec8ea/32.png) [@The\_Great\_Philosopher](https://boards.straightdope.com/u/The_Great_Philosopher)\ **Post date:** [June 17, 2009, 3:20pm UTC](https://boards.straightdope.com/t/why-arent-airliner-black-boxes-designed-to-float/500073/4 "2009-06-17T15:20:50Z")
They’re attached to the plane… ---
**Author:** ![Tenebras](https://avatars.discourse-cdn.com/v4/letter/t/977dab/32.png) [@Tenebras](https://boards.straightdope.com/u/Tenebras)\ **Post date:** [June 17, 2009, 3:24pm UTC](https://boards.straightdope.com/t/why-arent-airliner-black-boxes-designed-to-float/500073/5 "2009-06-17T15:24:10Z")
Everything else on the damn plane floats, I’m surprised the whole wreck doesn’t just bob at the surface. Also, the cushions from your couch may not be used as a floatation device, it turns out. \ ---
**Author:** ![Dag\_Otto](https://avatars.discourse-cdn.com/v4/letter/d/439d5e/32.png) [@Dag\_Otto](https://boards.straightdope.com/u/Dag_Otto)\ **Post date:** [June 17, 2009, 3:35pm UTC](https://boards.straightdope.com/t/why-arent-airliner-black-boxes-designed-to-float/500073/6 "2009-06-17T15:35:18Z")
I don’t think I’ve read the other thread, so maybe this has been covered. **Telemark** lists several good points, but what about a redundant recorder located in a different part of the plane? ---
**Author:** ![Spiff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/spiff/32/9852_2.png) [@Spiff](https://boards.straightdope.com/u/Spiff)\ **Post date:** [June 17, 2009, 3:37pm UTC](https://boards.straightdope.com/t/why-arent-airliner-black-boxes-designed-to-float/500073/7 "2009-06-17T15:37:40Z")
> [@Telemark](#): > > We just did this in another thread. I did do a search before posting my question, but nothing turned up. Was the topic covered in a thread mainly focused on a different aspect of the crash?