For 15 years, a Lufthansa jet has been measuring the atmosphere on passenger flights, and the free data now help scientists track ozone, water vapor, and weather

Somewhere over the Atlantic, this week, a Lufthansa Airbus A340-300, called "Viersen," made its usual run between New York and Frankfurt on flight LH405. To the passengers aboard, nothing about the flight looked any different. But this particular aircraft, registration D-AIGT, has been quietly doing something extra since 2011.

A small instrument under the cockpit has sampled outside air on flights for 15 years, contributing to one of the world’s most important long-term climate datasets. According to Lufthansa Group's newsroom announcement, the July 7 to July 8, 2026, New York to Frankfurt flight marked the 15th anniversary of the aircraft’s ongoing atmospheric monitoring as a scheduled passenger service.

How a 2011 flight to Lagos started it all
In fact, the story begins on July 8, 2011, when D-AIGT flew from Frankfurt to Lagos, Nigeria, with her usual passengers. That flight also marked something else. According to Lufthansa Group, this was when Lufthansa and Germany’s Forschungszentrum Jülich research center became the first airline-research partnership to launch a long-term scientific observation of Earth’s atmosphere from scheduled commercial flights, based on a measurement system called IAGOS, short for In-service Aircraft for a Global Observing System.


If you're an American on business or vacation, travelling that same JFK-Frankfurt route, it's worth knowing this particular jet has been doing double duty for the last decade and a half, carrying tourists across the Atlantic while collecting climate data nobody else was collecting at that scale.

The science hiding under the cockpit
The setup itself is quite simple. Two small probes, attached to the fuselage, pulling in outside air as the plane flies. Lufthansa Group said the data is transmitted automatically after each flight to a central database run by France’s CNRS, the Centre National de la Recherche Scientifique, in Toulouse, which cooperates closely with Forschungszentrum Jülich on the program.

The system directly measures gases such as ozone and water vapor in flight, at cruising altitudes where a lot of atmospheric activity that affects climate actually happens, the official IAGOS program website notes. According to the paper, ‘Global-scale atmosphere monitoring by in-service aircraft – current achievements and future prospects of the European Research Infrastructure IAGOS,’ published in Tellus B, this use of commercial aircraft allows researchers to make atmospheric measurements at a volume and geographic spread that dedicated research planes or satellites struggle to match, simply because commercial jets are already flying thousands of routes around the globe every day. The authors note that each aircraft flies roughly 500 missions a year and that the program’s final design aims at a fleet of 20 aircraft to provide global-scale coverage of key atmospheric variables.

Three decades of quiet data collection
This kind of research at Lufthansa dates back to before 2011. IAGOS’s predecessor system, MOZAIC, collected measurements reliably between 1994 and 2014 on two of Lufthansa Group’s Airbus A340-300 aircraft, the company said. The MOZAIC and IAGOS programs have together conducted more than 37,500 measurement flights, according to Lufthansa Group, creating what scientists say is one of the world’s largest long-term datasets of atmospheric ozone and water vapor.

The system is now on board three aircraft operated by the Lufthansa Group. In February 2015 and November 2022, two Airbus A330-300 jets of Discover Airlines, registrations D-AIKO and D-AIKE, also joined the effort along with the “Viersen.” All three aircraft together gather atmospheric data daily on routes around the world. There are currently ten aircraft from eight different airlines worldwide fitted with IAGOS instruments.

Why this matters for weather forecasts in the US
This is not just an aviation trivia point. According to Lufthansa Group, the data set is currently used by around 400 research organizations worldwide to monitor long-term changes in the atmosphere, improve climate models, and enhance weather forecasting. The program also feeds into a World Meteorological Organization global aircraft-based observation system, the same wider international network that feeds into the forecasts Americans check on their phones each morning before deciding whether to grab an umbrella.

Because the data is freely and openly shared, universities, weather agencies, and climate researchers in the United States have access to the exact same measurements as scientists in Europe. Part of the reason that a program based on regular passenger flights has remained scientifically relevant for more than 30 years, rather than being a short-lived experiment, is that open access over decades.

The bigger picture
Nothing changes for passengers boarding these flights. There is no special seat, no unusual announcement, no different boarding process. But for scientists trying to track how the upper atmosphere is changing over time, that daily transatlantic hop is quite significant. As global air traffic continues to increase, one of the better inexpensive ways to watch the sky is to use existing commercial routes to collect climate data, one regular flight at a time.

It’s a reminder that meaningful climate science doesn’t always need a dramatic new mission. Sometimes it just means attaching a little sensor to a plane that’s going to fly anyway, and letting 15 years of ordinary flights quietly add up to something scientifically significant.