A computer glitch that brought the Paris airport of Orly to a standstill Saturday has been traced back to the airport's "prehistoric" operating system. In an article published Wednesday, French satirical weekly Le Canard Enchaîné (which often writes serious stories, such as this one) said the computer failure had affected a system known as DECOR, which is used by air traffic controllers to communicate weather information to pilots. Pilots rely on the system when weather conditions are poor.

DECOR, which is used in takeoff and landings, runs on Windows 3.1, an operating system that came onto the market in 1992. Hardly state-of-the-art technology. One of the highlights of Windows 3.1 when it came out was the inclusion of Minesweeper — a single-player video game that was responsible for wasting hours of PC owners' time in the early '90s.

DECOR's breakdown on Saturday prevented air traffic controllers from providing pilots with Runway Visual Range, or RVR, information — a value that determines the distance a pilot can see down the runway. As fog descended onto the runway and engineers battled to find the origin of the glitch, flights were grounded as a precaution.

"The tools used by Aéroports de Paris controllers run on four different operating systems, that are all between 10 and 20 years old," explained Alexandre Fiacre, the secretary general of France's UNSA-IESSA air traffic controller union. ADP is the company that runs both Orly and Paris' other airport, Charles de Gaulle, one of the busiest in the world.

"Some of ADP's machines run on UNIX [an operating system favored by universities and start-ups in the '80s], but also Windows XP," said Fiacre, who works as an aviation security systems engineer.

"The issue with a system that old is that people don't like to do maintenance work," explained Fiacre. "Furthermore, we are starting to lose the expertise [to deal] with that type of operating system. In Paris, we have only three specialists who can deal with DECOR-related issues," said Fiacre.

"One of them is retiring next year, and we haven't found anyone to replace him," he added.

Fiacre compared the challenges of running the Windows 3.1-supported DECOR to the issues faced by NASA with its Voyager program, which was launched in 1977. Voyager 1 and Voyager 2, the two robotic probes that are used by NASA to study the outer solar system, rely on 250 kHz central processing units made by General Electric.

These 40 year-old computers are less powerful than today's pocket calculators, and use out-of-date programming languages like FORTRAN, which means that, with the impending retirement of the last engineer from the original Voyager mission, NASA will soon be recruiting a new expert on 1970s computer programming.

Punched card from a FORTRAN program (via Wikimedia Commons)

French aviation systems engineers face their own maintenance challenges, compounded by the unavailability of spare parts for these outdated machines. "Sometimes we have to go rummaging on eBay to replace certain parts," said Fiacre. "In any case, these machines were not designed to keep working for more than 20 years."

According to Le Canard Enchaîné, France's transport minister has promised that "equipment will be upgraded by 2017." But Fiacre is not so sure about this timeline. "In my opinion, we'll upgrade in 2019 at the earliest, perhaps even in 2021," he said.

Fiacre described Saturday's breakdown as a "warning," but noted that the systems failure had in no way "endangered passengers, since [air traffic] controllers took a number of precautionary measures to eliminate all risk."

ADP has not yet released a statement concerning Saturday's disruption of air traffic.

The grounding of flights in Paris is not the first incident to highlight the lack of airport resources and the use of outdated systems to ensure safety in the skies, and not just in France.

In December 2014, airspace over London was closed for 36 minutes and some fifty flights were canceled following a computer failure that was later blamed on 50-year-old software.

Earlier this year, two hackers were awarded one million "bug bounty" air miles each by United Airlines after flagging up flaws in the company's web security system.

One person who was put out by Saturday's air traffic disruption is French politician Alain Juppé, one of the contenders in the primaries for the French Republican Party's 2017 presidential nomination. Juppé was due to fly to Paris from the southwestern city of Bordeaux to attend a party conference.

Au moment de décoller de Bx,Orly est fermé.Impossible de rejoindre le Conseil national LR à temps. Dommage!J'avais préparé un bon discours. — Alain Juppé (@alainjuppe)November 7, 2015

About to take off from Bordeaux, Orly is closed. Unable to get to Republican national council on time. Shame! I had prepared a good speech.

An aviation engineer interviewed by Le Canard Enchaîné Wednesday raised the possibility of similar disruptions during the UN's COP 21 climate change conference, which will be held in Paris, from November 30 to December 11. "Imagine, during COP 21, the comings and goings of heads of state being disrupted because of prehistoric software," he told the weekly.