IATA-RAeS Workshop 2026: Day 2, Session 5

Why It Matters

Enhanced aircraft water‑vapor observations will sharpen weather forecasts and enable contrail‑avoidance strategies, directly reducing aviation emissions and supporting global climate goals.

Key Takeaways

• Aircraft-based water vapor sensors crucial for contrail avoidance.
• Current programs: nine EU aircraft, ~135 US aircraft equipped.
• Sensor challenges: low cost, lightweight, self‑calibrating, wide range.
• Regulatory and data transmission hurdles limit widespread adoption.
• Public‑private funding needed to expand observations and improve forecasts.

Summary

The IATA‑RAeS Workshop Day 2, Session 5 focused on advances in aircraft‑based observations for validation and contrail‑avoidance forecasting. Led by Carmen Emma of the German Meteorological Service, the session highlighted the World Meteorological Organization’s expert team on aircraft observations, which gathers temperature, wind, humidity and emerging turbulence data from commercial fleets. Key insights included the current WVSS2 sensor program—nine European aircraft and roughly 135 North‑American aircraft equipped with water‑vapor sensors—and the technical push for low‑cost, lightweight, self‑calibrating sensors capable of measuring 10 ppm to 25 000 ppm. Participants discussed regulatory hurdles such as supplementary type certificates, data‑link options (ACARS, e‑flight, ADS‑B), and the need for free, real‑time data distribution to global NWP centers. Funding and public‑private partnerships were identified as critical to scaling the network. Notable examples featured Nicolas outlining sensor specifications and integration challenges, while DWD’s Dr Marius Noman demonstrated how the ICON model with a two‑moment scheme assimilates humidity observations to locate supersaturated regions (ISSR) for contrail prediction. Stakeholder meetings underscored the consensus to standardize sensor specs, enhance NWP models, and formalize collaborations between WMO, IATA, airlines, and regulatory bodies. The implications are significant: richer humidity data will reduce forecast uncertainty, enable more accurate contrail‑avoidance routing, and lower aviation’s carbon footprint. Achieving this requires coordinated investment, regulatory alignment, and expanded sensor deployment, positioning the aviation industry as a key contributor to climate mitigation and improved weather services worldwide.

Original Description

Recording of Session 5: Advances in observations for validation and ISSR forecasting from the IATA-RAeS Workshop 2026 - Contrail Management: progressing towards risk-informed decision making, which took place from 9-10 March 2026.

This event was organised in partnership with the IATA.

Organising Committee

Dr Nellie Elguindi - Manager non-CO2 emissions, IATA

Prof Dr Nicolas Bellouin - University of Reading

Prof Dr Florian Allroggen - Massachusetts Institute of Technology

Prof Dr Ian Poll - Emeritus, Cranfield University

Ms Jill Blickstein - Vice President, Sustainability at American Airlines

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Session 5: Advances in observations for validation and ISSR forecasting

Chair: Dr Carmen Emmel, German National Meteorological Service

Setting the scene

Dr Carmen Emmel -German National Meteorological Service

Developing a water vapor sensor suitable for contrail avoidance - challenges and roadblocks

Nicolas Rivaben – World Meteorological Organization (WMO)

(NO RECORDING) Water vapour sensors and IAGOS in CICONIA

Dr Hannah Clark – IAGOS

Improving ISSR forecasting with aircraft-based observations - key learnings from MEFKON + developing a weather forecast accuracy score for flight planning purposes

Dr Marius Neumann – German National Meteorological Service (DWD)

Dr Björn Beckman - German National Meteorological Service (DWD)

Observationally Driven Confidence in Contrail Mitigation

Dr Jonathan Itcovitz - Imperial College London

Dr Vincent Meijer - TU Delft University

(NO RECORDING) Observing long-lived longwave contrail forcing using GOES-16 satellite data

Aarón Sonabend - Google

Validating contrail predictions with observations from wide-angle groundbased cameras – a proof of concept with SWISS International airlines

Tanguy Chauvet - SII

Dr Ben van Lier - SWISS International Air Lines

Laurent Sauvage - Reuniwatt

Maxime Paillassa - SII