Is the US using surveillance drones to look for the plane?

[FarCenter]

7. The Global Hawk would seem to be suitable for this work.

I doubt that there are all that many of them.

The Northrop Grumman RQ-4 Global Hawk is an unmanned aerial vehicle (UAV) surveillance aircraft. It was initially designed by Ryan Aeronautical (now part of Northrop Grumman), and known as Tier II+ during development. In role and operational design, the Global Hawk is similar to the Lockheed U-2. The RQ-4 provides a broad overview and systematic surveillance using high resolution synthetic aperture radar (SAR) and long-range electro-optical/infrared (EO/IR) sensors with long loiter times over target areas. It can survey as much as 40,000 square miles (100,000 km2) of terrain a day.

http://en.wikipedia.org/wiki/Northrop_Grumman_RQ-4_Global_Hawk

On the other hand, if the pilot ditched the 777 without it breaking apart very much, there wouldn't be much on the ocean surface to detect.