Over an alfalfa field in California's San Joaquin Valley, a small crop-spraying plane is flying low to the ground. Unlike traditional aircraft, this one has no pilot on board. "We can actually go lower than a human pilot can," says Russ Marotzke, a flight test engineer at Pyka, as the aircraft skims over the crops. Flying at a lower altitude helps reduce the spread of chemicals into the air, meaning less spray is needed compared to conventional methods. Pyka, a startup based in a converted World War II hangar near San Francisco Bay, builds self-flying aircraft designed for tasks like crop spraying or delivering cargo. It is one of a small group of companies working to bring autonomous fixed-wing aircraft into commercial use. While much of the attention in autonomous aviation has focused on electric vertical take-off and landing (eVTOL) aircraft, often called urban air taxis, a quieter race is underway to develop self-flying planes for more practical, immediate tasks like crop spraying and cargo delivery. Eventually, some companies hope to use these aircraft for transporting passengers. Michael Norcia, Pyka's co-founder and CEO, envisions a future where fleets of self-flying planes could carry passengers along the U.S. coasts. He believes this might happen before the eVTOL industry reaches its full potential. At one of Pyka's test sites, about 80 kilometers east of its factory, Marotzke and a colleague are testing a software update on a demonstration aircraft. Dozens of Pyka planes are already in use in Brazil, spraying crops like cotton and soybeans. These planes are fully electric, with a battery in the nose and a 300-liter spray tank in the middle. They have an 11.5-meter wingspan, which makes them more like small planes than drones. Engineers use a computer to mark the areas to be sprayed, and the software plans a route that avoids obstacles like power lines. The plane takes off, flies for about 15 minutes, and then lands itself for a refill before resuming its mission. Autonomous flight is different from the autopilot systems found in many modern cars and planes. Autopilot assists with certain functions, like maintaining speed or staying in a lane. Autonomous systems, by contrast, aim to handle the entire flight, including takeoff and landing, with minimal human input. Despite the more predictable environment of the skies, autonomous aircraft have developed more slowly than self-driving cars. This is partly because major tech companies have focused heavily on cars, and partly because aviation has stricter safety standards. Mykel Kochenderfer, an expert in aviation autonomy at Stanford University, notes that the potential consequences of air accidents are more severe, making the regulatory hurdles higher. Military interest has helped advance the technology, with many companies securing defense contracts that allow them to test their systems with fewer regulatory barriers. In the U.S., Pyka's crop-sprayer is the largest autonomous fixed-wing aircraft approved for commercial use, though operations are limited to specific agricultural settings and require a ground operator and visual observer. The company aims to increase production from about two dozen planes a year to 1,000 by 2030. Meanwhile, the UK is still evaluating such operations, though British firm Windracers is seeking permission to launch an autonomous cargo service in remote regions like Shetland and Orkney. Supporters argue that autonomous aircraft could help address pilot shortages, improve safety, and reduce costs. However, pilots' groups remain cautious, with concerns about safety and visibility of small, uncrewed aircraft in the sky.