I was personally involved in this invention story. It solved an unrecognized problem that emerged in 1968 and was such a new issue that no one foresaw its scope until years later. In fact, the scope of the problem grew to worldwide proportions so fast that it could have become debilitating to every developed nation on Earth. The invention that solved the problem had no issued patents, no one got credit for its success; the inventors were never even recognized. Yet this invention spread worldwide within ten years and probably has benefited each one of us—maybe even you.
In spring and summer 1968, newspapers chronicled an alarming rise in the number of airplane hijackings. On March 13, the Washington Post reported, “Another U.S. jetliner—the second in three weeks—was hijacked over Florida today and forced to fly to Havana.”1 On September 21, the Post noted, “An Eastern Air Lines jet bound to Miami from San Juan, Puerto Rico, was hijacked to Cuba today, becoming the ninth commercial airliner diverted to the Caribbean island this year.”2 And the situation continued to worsen; on November 25, a New York Times headline read, “Second Jet in a Day Is Hijacked to Cuba.”3
The statistician Robert Holden notes that between 1968 and 1972, “there were 326 hijacking attempts worldwide, or one every 5.6 days. These included 13.7 attempts by individuals who boarded flights in the United States, or one such attempt every 13.3 days. Newspapers, television, and other mass media constantly carried stories about aircraft hijackings, and it was often suggested that the motivation to hijack planes spread from individual to individual as a result of the media coverage.”4 As I have written elsewhere, “The drill in the cockpit to take the skyjacker to Havana was so well known that pilots were advised to cooperate with armed interlopers: fly them to the Caribbean isle, let passengers obtain their ceremonial box of cigars and some rum, and then continue on to the original intended destination with as little further interruption as possible.”5
It seemed as if no one had any idea how to stop airline passenger hijackings—not federal law enforcement agencies, the military, professional security people, absolutely no one. This represented a serious problem worldwide.
Some humorous solutions were proposed, like building a replica Havana airport in Miami to trick hijackers. (FAA Administrator John Shaffer pointed out, “A fake airport would work once and that’s all.”6) And other more concrete tactics were put into use, including metal detectors, sky marshals on planes, and behavioral profiling of passengers waiting for their flights.7 (I might note that Infinetics, a one-person company in Delaware managed by Melvin Schwartz, made a walk-through metal detector called the Friskem Walk-Thru Station that was tested by the Federal Aviation Administration (FAA) in late 1968. Walk-through metal detectors had been used in prisons and jails for more than a decade, but Infinetics offered an inexpensive, less sensitive one, only for handguns, for use in courts and higher security locations. By the end of 1968, Eastern Airlines had purchased a Friskem for its Gate 14 at Washington National Airport, where they used it “occasionally” for their flights to Miami.)
However, at Philips Broadcast Equipment Corp. Government Systems Group in Mahwah, NJ, engineer George W. Shepherd Jr. not only recognized the seriousness of the hijacking problem but also had a better idea about how to solve it. He discussed it with engineering manager Neil Diepeveen, who agreed that, yes, Shepherd might have a solution. Diepeveen “found” some company money that permitted this to become an “unauthorized” feasibility study in their company group (or, as some would call it, a “skunk works”).
And what was the great idea? To design a system using very low level X-rays to view the contents of articles such as briefcases, purses, and suitcases that airline passengers carried onboard aircraft. In particular, one would be able to see a gun or weapon inside the article. Aircraft could be made more secure by (1) having passengers walk through metal detectors AND (2) having all of their hand-carried articles X-rayed by a security team. How radical an idea. But it was so radical that no means to do this was yet available. Conventional high dose X-rays were too dangerous, but the idea of low dose X-rays to provide a visual image was perfect—the technology just had to be invented!
By that summer of 1968, the low-dose X-ray scanner project was well underway. In early 1969, Shepherd’s group was able to make safe X-ray exposures of briefcases to show the contents. Not only did it work as they hoped, but the X-ray dose was so low that even photographic film was not affected.8 Shepherd and Diepeveen were so pleased with the results that they named this first low-dose X-ray scanner the “Saferay.”
The scanner concept and prototype were ready to demonstrate to the company's senior managers by the summer of 1969. This was an exciting event as it was their first exposure of the “unauthorized” project. The company’s senior management agreed that this solution to the aircraft hijacking problem was practical. This is where I came into the story.
I arrived at Philips Electronic Instruments in Mt Vernon, NY, in the spring of 1970. I was Principal Scientist—X-rays in the New Product Development/Engineering Dept., and was assigned to be the Radiation Safety Officer. The Saferay people had contacted the manager of engineering to have someone “officially” measure the X-ray dose per inspection and the external X-ray scatter from the Saferay unit, which was set up in a demo room in Mahwah. So I went over to Mahwah several times with a special X-ray dosimeter that measured pulsed X-rays, rather than a steady beam. I wrote a report, and my X-ray dose numbers were used in the official Saferay documents—and also in a Popular Science article published in the November 1970 issue!9
Now the Saferay needed to be shown to federal law enforcement officials. All George and Neil had to do was assemble the prototype into a cabinet, write up a description of the Saferay, and arrange for a government demonstration.
So during the summer of 1970, several FAA officials were invited to Mahwah, NJ, to see the Saferay.10 They were very impressed—so impressed that the Philips public relations manager arranged for a larger government demonstration at Washington National Airport (now Ronald Reagan Washington National Airport), and George and Neil would perform the demonstration.
On September 25, 1970, in an airplane hangar at Washington National Airport, the Saferay was demonstrated to more than 50 United States government officials, including members of the FBI, Secret Service, US military branches, White House officials, and more. This first low-dose X-ray scanner amazed the officials; the idea of visualizing the contents of bags and articles in such a simple manner was beyond imagination! What a success! And that very evening, General Benjamin O. Davis Jr., Director of Civil Aviation Security in the US Department of Transportation, made a telephone call to John Shaffer, Administrator of the FAA, stating that a solution to the airline hijacking problem had finally been found.11
Several Saferay units were installed and used at airports over the next two years, in answer, in part, to a new FAA rule, issued on February 1, 1972, that instructed air carriers “to use a screening system, acceptable to the FAA, that would require screening all passengers ‘by one or more of the following systems: behavioral profile, magnetometer, identification check, physical search.’” With hijackings continuing, the FAA strengthened its stance, issuing “emergency rules that required screening all passengers and carry-on baggage on all certified, scheduled passenger aircraft.”12
In 1972, Philips introduced the Conveyor Saferay System, which allowed a steady flow of carry-ons to be examined. By this time, competitors had entered the market, with Bendix Corporation being the most successful. Bendix had dozens of professional salespeople selling services, equipment, and spare parts to well-established airline and airport customers. They had made their own version of the Saferay (called the BendixRay) and received many orders before the January 5, 1973, deadline for federal mandatory airline passenger Inspections. (FAA records show that by 1974, Bendix had installed 80 X-ray units in US airports (31%) while Philips Saferay had installed only 36 units (14%) out of a total of 260 X-ray units installed).
Organizational changes at Philips disrupted Saferay development and distribution. Moreover, the Saferay system was designed originally to be loaded manually and perform only one inspection every minute or so, but with the conveyor sending 10 to 20 articles through for inspection each minute, the X-ray tube of the unit required constant repair and/or replacement. At an average of 100 people per airplane and 2 items per person, each X-ray tube had to be replaced about every 5 airplanes (basically every day). This became a service nightmare!
During 1973, only a few Saferays were sold and by December 1974, the product was discontinued and the Saferay name was eliminated. No recognition was ever given to George W. Shepherd Jr. or Neil Diepeveen for their invention. It is sad that neither the United States federal government, the Transportation Security Administration (TSA), nor any other aviation organization ever recognized them. Not only did screening improve aircraft security and safety, it also factored into a decrease in aircraft hijacking and threats. Surprisingly, what had been unforeseen from the beginning was that aircraft threats would morph from simple hijackings with a pistol to hijacking with threats like bombs, poisons, and other weapons, and move beyond extortion of the airlines to criminal and political terrorism that could destroy airplanes in mid-flight.
Without the invention of the Saferay in 1970, thousands of airline passengers would have been in jeopardy and dozens of aircraft destroyed during the 1970s. Hijackings, terrorism, and criminal acts may have even destroyed the passenger airline industry and worldwide tourism. So even without patents, without credit for its success, without the inventors ever being recognized, human society certainly appreciates one small part of “humanity”—the invention and innovation process behind the Saferay. And as a consequence, airline passenger security screening will be with us forever.
David Haas studied physics, biophysics, and X-ray crystallography, held postdoctoral fellowships in Europe, and then worked as Principal Scientist (X-rays) at Philips Electronic Instruments. He and his wife Sandra later developed and manufactured sophisticated security ID products for 20 years. They hold 50 patents and have authored several monographs, publications, and videos.
1 “DC-8 Is Hijacked to Cuba: U.S. Jetliner Hijacked to Cuba,” Washington Post, March 13, 1968, A1.
2 “Jet, 53 Aboard, Hijacked To Cuba, 9th This Year,” Washington Post, September 21, 1968, A3.
3 “Second Jet in a Day Is Hijacked to Cuba,” New York Times, November 25, 1968, 1.
4 Holden, Robert T. "The Contagiousness of Aircraft Hijacking." American Journal of Sociology 91, no. 4 (1986): 874-904, https://www.jstor.org/stable/2779961.
5 Robert McCrie and David Haas, “Why Airline Passenger Screening Will Be With Us Forever: Past, Present, and Prospects for Air Travel Safety,” Journal of Applied Security Research 13, no. 2 (April 3, 2018): 152, https://doi.org/10.1080/19361610.2018.1422359.
6 John H. Shaffer, “What We Can Do to Stop Hijacking,” Spartanburg (SC) Herald-Journal, June 15, 1969, Family Weekly, 4-5.
7 Kenneth C. Moore, Airport, Aircraft, and Airline Security, 2nd ed (Boston: Butterworth-Heinemann, 1991): 6-10.
8 Someone must have enquired with Kodak's Technical Advisors as to the maximum amount of X-ray exposure that could be called “film-safe” for consumer films. Photographic film had been used since 1900 to record X-ray images so any X-ray inspection device would have to produce far less than a normal amount for X-ray exposure. Kodak was the senior partner in the photographic industry standards group. “The National Photographic Manufacturers Council,” and by 1972, they had established that 0.5 milliroentgens per inspection is considered a “film-safe” exposure. I was asked to make the measurements for the Saferay, and found them well below 0.5 milliroentgens for each inspection.
9 The reporter from Popular Science provided details on the operation of the Saferay: “Here's how this short-pulse X-ray technique works: The weak momentary image on a fluoroscope-type screen is viewed by a TV camera having a light-boosting image intensifier (similar to those in the Army's night-vision Starlight Scope) ahead of the camera tube. Electronic switching is used to trigger the recording of one TV frame on a video recorder during the period of peak image level. The stored frame is then viewed directly on a TV monitor. Exposure time is 50 nanoseconds (50 billionths of a second) and the radiation required to produce these images is approximately 0.2 milliroentgen. This is harmlessly small—well below the level of radiation you receive daily from naturally occurring sources in the environment. Incidentally, unlike conventional X ray, this short-pulse, extremely low-dosage X ray will not damage photographic film.” Emphasis in original. Paul Wahl, “How Science Will Foil the Skyjackers,” Popular Science, November 1970, 123.
10 The Popular Science reporter also attended the demonstration and reported, “An ordinary overnight bag was packed with clothing, a shaving kit, a book-and a revolver. The bag was shoved into the slot of a mock-up airline check-in counter, a button was pushed, and an X-ray image of the bag and its contents instantly appeared on a TV monitor screen. The picture was remarkably sharp and clear-there was no mistaking the revolver.” Wahl, “How Science Will Foil the Skyjackers,” 123.
11 Davis later wrote, ““The federal antiskyjack campaign intensified in the spring of 1972. In May, the FAA announced the purchase of $3.5 million worth of electronic screening devices. . . . [D]uring the summer of 1972.. . . [t]he DOT's Office of Transportation Security was looking for the answers to three pressing questions: (1) how best to improve the program as it then existed; (2) how best to utilize technological improvements in security, such as metal detectors and low-wattage X-ray machines, which were then in production and would be available in the near future and (3) how to build into the program the flexibility necessary to respond to the different kinds of hijackings.” Emphasis added. Benjamin O Davis Jr, “The Government’s Response to Hijacking,” Villanova Law Review 18, no. 6 (1973): 1015, https://digitalcommons.law.villanova.edu/vlr/vol18/iss6/5.”
12 Airline Passenger Security Screening: New Technologies and Implementation Issues (Washington, D.C.: National Academies Press, 1996): 6, https://doi.org/10.17226/5116.