The flight data recorder for flight AirAsia Flight QZ8501?

Both have been found.

The orginal recorders were analog wire recorders, they could not record voice and flight data on one reel. So regulations called for 2 devices, and aircraft were wired for 2 devices.

It would be possible to have a digital unit to record both types of data. Sounds like a simple change right? First you need to have regulations changed - these are global, so pretty much every ICAO member has to weigh in and approve. Next you need engineering standards. Now manufacturers need to design, test, and certify new units. But now you have boxes that only work on new aircraft designed to use them - exisiting planes send voice and data on seperate paths. So now you need to design and certify retrofits for every type of aircraft and avionics suite, and each installation needs to be inspected and approved as it is performed. Given the lifespan of aircraft, it would be decades and cost hundreds of millions of dollars before the change would be fully in place. And since losing only one black box is rare, there is no functional improvement.

This is why change happens pretty slowly in aviation. For example, the universally accepted navigation system is still based on 1950's and 60's technology, You can fly IFR without a GPS, VOR is still the standard.

The forces of the crash separated the boxes on impact. Like if you were to take two coins and throw them they probably wouldn't be within an inch or two of each other when they landed. It's like that but with much stronger forces. Plane manufacturers design the airplane with two different boxes so that way if one becomes damaged or lost the they still have the other one.

yes. why not put three, or four units.. guess what. the AUDIO storage is a reel, overwritten every so often. ANALOG data. flight data are signals, DIGITAL data. go figure.

cost-prohibitive? probably not. but not reasonable, either.

edit:

work on your reading comprehension before you start talking into the aviation stuff.

i said..

>without any appeal to authority<

you think you are the ONLY one thinking out of the box? oh well. that's what i am saying. peopl HAD been thinking about that. and they, EDUCATED about the subject, realised it's not cost effective at the moment. sometimes thinking out of the box means dumping outside of box.

ever had a cat miss its toilet? that's thinking out of the box, too.

two separate units reduces the chance of losing all data.

there is nothing more offensive than somebody who clearly hasn't a clue on the subject telling those who spend their lives thinking about this sort of stuff that they need to think outside of the box.

It increases the chance that they won't both be missing.

Because when an aircraft comes crashing down to earth and hits the water at a high rate of speed things tend to NOT stay in one piece and instead usually break apart and go flying in all directions.

If you think you have a better idea of how they should be designed why not try and get an aerospace engineering job or go work for the FAA and actually do it.

Cause complaining about you supposed "better" ideas to to us....does nothing useful and doesn't make you look any better than the parachute trolls

Well, for starters, you can find one and not the other. If they were the same unit, then you may end up finding nothing.

no idea about this