World Meteorological Organization

1. Introduction

Meteorological observations from upper air sources play a crucial role in the enhancement of Numerical Weather Prediction (NWP) products and severe weather forecasting. A notable data source in this regard is aircraft-based observations (ABO), which serve to complement the extant radiosonde network. ABO data has been identified as having the potential to significantly enhance the global NWP system, as outlined in the recommendations of the WMO NWP Impact Workshop.

A number of ABO sources have been developed by WMO Members and Air Navigation Services Providers (ANSP), with the objective of increasing upper-air observations. These include Automated Data Surveillance (ADS) and Secondary Radar (Mode S), among other systems developed by the aviation industry. Nevertheless, the most well-known system is the Aircraft Meteorological Data Relay (AMDAR), a WMO programme that utilises the existing aircraft avionics (or retrofitted with water-vapor sensors) for the collection of meteorological data. This information is then transmitted to the respective National Meteorological and Hydrological Services (NMHSs) to be exchanged in real time through the WMO Information System (WIS). This improves critical numerical weather prediction for aviation purposes and general community.

Since late 1990, there has been an increase in AMDAR data, which continued until 2020 due to economic issues caused by the global aviation industry's downturn related to the outbreak of the COVID19 pandemic. While the aviation sector has demonstrated notable resilience and recovery since then, AMDAR programmes have not yet regained their previous rate of observations.  

A significant challenge persists in accessing data from regions with limited data coverage, including Latin America, Africa, and certain parts of Asia. These concerns primarily stem from the limited availability of communications, technology, and support from meteorological and aviation stakeholders.

Despite these challenges, some stakeholders have made efforts to address these issues, albeit with limited success. The necessity for upper-air observations is paramount to the functioning of ABO programmes worldwide, and NMHS are collaborating closely with the aviation sector to mitigate and adapt the social impact of climate change through its contribution to the United Nations Early Warning for All Initiative (EW4ALL), pillar 2- Observations and Forecasting, among others.

This workshop aims to create a collaborative space for global stakeholders to discuss the integration of new aircraft-based observation (ABO) platforms, with the goal of strengthening synergies between meteorological and aviation-industry communities. Its specific objectives are to improve the numerical weather prediction (NWP) systems critical for aviation services, encourage aviation standardization bodies to support ABO standards, and explore cost-effective methods for gathering ABO data. Furthermore, it seeks to develop new collaborative ways to monitor aviation-related environmental hazards like contrails and non-CO2 emissions, and to demonstrate how the ABO program contributes to UN initiatives by enhancing data coverage over sparse areas, improving forecasts, and directly supporting the Early Warnings for All (EW4All) initiative.

To facilitate the development of the regional ABO programme, WMO hosted the Global Aviation Stakeholders meeting between 15, the morning of 17 September 2025 at WMO HQ in Geneva, Switzerland.  

The ET-ABO Meeting took place in the same building in the afternoon of 17 September and the entire day of 18 September 2025.

2. Scope

Global Aviation Stakeholders meeting focused on five main areas: introducing the various types and benefits of aircraft-based observations (ABO); examining their role in early warning systems and weather prediction; discussing technological advances in sensors and data communication; exploring ABO's environmental contributions, such as contrail avoidance and emission monitoring; and reviewing progress on new data sources like weather unmanned aerial systems (Wx-UAS) and their regulations.

The ET-ABO meeting focused on reviewing reports from its leadership, regional leads, and the WMO Secretariat, as well as from its various subgroups; it also involved discussions relevant to WIGOS and the future of WMO ABO Programme alongside developing strategies to address recommendations from the Global Aviation Stakeholders on ABO Meeting.

5. Date and Venue

The Workshop was organized as a three-day hybrid event and located at the WMO HQ Building, Geneva, Switzerland. The ET-ABO meeting was one-day and half hybrid event as well.

6. Programme of GASM

Final GASM programme with the speaker's presentation is available here.

Final report will be available soon.

Short meeting notes from day 1, day 2 and day 3 will be available soon.