U2 overflights
U2 has a synthetic aperature radar (SAR) payload which sees through the clouds. I have wondered why this has not been deployed. I don't know if NASA has this capability, but I know DOD has this capability. The government could collect and view this data in real time, either overflying the search vehicles, or going out the night before, to help and narrow the search area.
BTW, Tomnod is using satellite SAR data on some of their images.