In the 1960s, Donald Bateman built a cockpit warning system after aircraft kept crashing into terrain; by 1973, the FAA was requiring the technology

Modern life is full of notifications: delivery alerts, streaming recommendations, battery warnings and more, most of which do not have a significant impact. The opposite has long been true in aviation, namely, that an alert should hint at a critical moment, and then it should be as brief, specific, and clear as possible. According to the National Inventors Hall of Fame, engineer C. Donald Bateman came up with the idea for the Ground Proximity Warning System (GPWS) in the 1960s after several fatal crashes, when airline owners decided to find a way for pilots to know when they were flying too low or near a mountain.

In turn, the same National Inventors Hall of Fame website reports that Bateman’s creation issued warnings whenever the aircraft was in danger of flying too low or over water. Meanwhile, Smithsonian’s Air & Space magazine adds that the system’s announcement changes depending on the height: from “Sink rate” to “Pull up” if the pilot does not correct the situation in time. For a person used to receiving dozens of notifications a day, Bateman’s invention is an example of how notifications can be formulated so that they contain as much information as possible while remaining concise and unobtrusive, even though, the earliest hardware took years to live up to that design goal.

A crash with a terrifying definition


Aviation has a name for the type of accident that led to the creation of this system: controlled flight into terrain, or CFIT. Per the Federal Aviation Administration (FAA), this is an event involving an airworthy aircraft and a crew that has passed all required inspections and tests, leading to the plane’s collision with the ground, bodies of water, or other obstacles without the crew realizing it.

FAA rulemaking documents on the subject state that several CFIT accidents in the late 1960s resulted in hundreds of deaths and that research in the early 1970s showed that many of these incidents could have been avoided if a ground proximity warning system had been installed in the planes. Flying into the ground was not a pilot error; the plane and the crew were completely fine, but they did not have the tools or the training to respond correctly to the situation.A CFIT accident isn't the result of a mechanical failure; the aircraft is airworthy and the crew is fully qualified, but investigations of these crashes, including the 2003 Peru accident, have generally pointed to a loss of situational awareness by the crew rather than pure bad luck. Bateman's system was built to close exactly that gap: giving pilots a tool to catch a dangerous flight path before it becomes irreversible.

As a result of these studies and formal recommendations from the National Transportation Safety Board (NTSB), the FAA required GPWS on large turbine-powered airplanes operated by scheduled airlines (Part 121) and on some large turbojets operated by charter and commuter carriers (Part 135), publishing the rule in the Federal Register on December 18, 1974 (39 FR 44439), with compliance required by January 1975. The National Inventors Hall of Fame instead dates the requirement to 1973, likely referring to when the FAA began moving toward the rule rather than the date it was finalized, so, as with the original article, it's worth flagging that sources describe this timeline somewhat differently depending on whether they mean the start of the process or the finished regulation.

An unglamorous genius behind the beep

For the most part, Bateman’s career was unglamorous: he was born in Saskatchewan, Canada, received a degree in electrical engineering at the University of Saskatchewan and then worked on aircraft safety systems at Honeywell (originally hired at Sundstrand Corporation, which later became part of Honeywell) before inventing the GPWS. Awards and distinctions, among others, include the National Medal of Technology and Innovation, and in 2005, he was inducted into the National Inventors Hall of Fame. He died on May 21, 2023, at the age of 91.

The first version of the system literally had blind spots

The system described in Air & Space magazine is almost unrecognizable compared to what we are used to today. The original GPWS used a radio altimeter that “looked straight down,” meaning that if the pilot was flying at an angle, the warning came too late: only 10–15 seconds before the accident or even less. At the same time, the article says that the display was also basic: it was not until later that they figured out how to make it easier to distinguish signals from noise, and for a long time the only visual indication was lights.

Modern aircraft are now equipped with the Terrain Awareness and Warning System (TAWS), the updated version of the GPWS. The magazine's reporting notes that this system allows looking ahead as well as below the plane, giving the pilot 30 to 120 seconds of warning and a rough picture of the terrain. The National Inventors Hall of Fame states that in addition to the TAWS, Bateman and his team developed more accurate methods of measuring the distance to the ground, wind shear warnings, and computer-generated color-coded topography.

The takeaway

Air & Space magazine also reports that in January 2003, a Fokker F-28 crashed on a cloudy mountain in Peru, killing all 46 people aboard (41 passengers and 5 crew), despite the plane being equipped with the original GPWS. Thus, although the technology significantly reduced the number of accidents, it could not eliminate them. On the other hand, it is hard to argue that the solution was not good enough: the fact that planes received a warning 10–15 seconds before the accident is incomparable to the millions of notifications that appear on our phones every day.

Still, it would be good to remember that the clarity and precision of a warning system depend on what it warns about and how it warns. The specificity of the alert is what separates it from the meaningless announcements of budget airlines (or the promotion of the same budget airline in a mobile app). In other words, a good example of technology that works is a system call that warns the pilot of a potential crash. It does not use up the user’s time; it does not resort to unnecessary effects; it states the problem clearly and offers a solution. It does not matter whether it is in the cockpit or on the mobile phone: the most important thing is for the user to understand what the notification is about and what actions need to be taken.