The first sign of trouble came when the pilots yoke-mounted GPS announced External power lost. Switching to battery. Before the pilot could wrap his head around that, the instrument panel went as dark as the inky night outside. Central Florida is thinly inhabited, offering few ground references. Fighting vertigo but keeping his cool, he knew that his Bonanza was trimmed for straight and level cruise. Using his GPS, he gingerly turned east toward the ocean with well-lit towns and cities hugging the shore, aiming at his home base, Boca Raton airport, KBCT. The engine droned along as if all was right with the world.