Ahhhhmmmmmm
If you were on a boat searching for pings on 37.5 and you started receiving them, maybe you would think about...
STOPPING THE BOAT
Is there something with to do with thermal layers that could stop signals from reaching the surface or whatever depth they were towing their sonar array at?
Why would they only receive the ping signal for 15 mins, a month after the plane went down?
Something is not right here. It doesn't make sense to me.