TRACY, Calif. — Last week, at a tiny airport in the dusty flatlands east of San Francisco, a red-and-white helicopter lifted gently into the air, hovering a few feet over the tarmac. It looked like any other helicopter, except for the small black cube attached to its nose.

Local officials spent the week testing this aircraft for a new emergency service, due for launch in January, that will respond to 911 calls via the air. But as this helicopter moves police officers and medical workers over the San Joaquin Valley, it will feed a more ambitious project. That black cube is part of a growing effort to build small passenger aircraft that can fly on their own.

Today, the helicopter is flown by seasoned pilots. But the new emergency service will be operated by SkyRyse, a Silicon Valley start-up that intends to augment small helicopters and other passenger aircraft with hardware and software that allow for autonomous flight, leaning on many of the same technologies that power driverless cars. These include the 360-degree cameras and radar sensors built into the nose of the aircraft.

“There are many things that must come to fruition before autonomous aircraft start flying people,” said Mark Groden, a co-founder and the chief executive of SkyRyse. “But we are developing the technology that can take us there.”