They're going to spend 4 days trying to relocate pings? Did someone throw away the ping coordinates?

[Glassunion]

14. Yes, they are trying to relocate the ping.

Yes, they can go back to the same location, however that does not automatically guarantee that they will hear it.

It is not a case of lowering the ping locator. It is designed to operate as a specific depth above the sea floor. 1000 feet, any lower and it the area that it can hear grows smaller, any higher and it can miss hearing what is below it. Given perfect conditions the pinger can be heard up to a mile away. However the ocean is not a constant. There are temperature variances, salinity variances, currents and streams at all different depths. These can actually amplify the signal to where it could be heard miles away from it's actual location or mask it even though you are very close.

4 days, is their best estimate based on weather, currents and sea surface conditions. They have to tow the locator at a very slow speed (3kts) to avoid doppler shift. They are listening for a very specific frequency of sound, if they travel too fast, as they approach it, it could increase the frequency out of the range that they are listening for or vice-versa if they are traveling away. This is an arduous process, and the best analogy that I have for it, is imagine mowing a lawn the size of Houston Texas with one lawn mower. It'll take a few days.