TAMDAR (Tropospheric Airborne Meteorological Data Reporting) is a weather monitoring system that consists of an in situ atmospheric sensor mounted on commercial aircraft for data gathering. It collects information similar to that collected by radiosondes carried aloft by weather balloons. It was developed by AirDat LLC, which was acquired by Panasonic Avionics Corporation in April 2013 and operated until October 2018 under the name Panasonic Weather Solutions. It is now owned by FLYHT Aerospace Solutions Ltd. TAMDAR (Tropospheric Airborne Meteorological Data Reporting) is a weather monitoring system that consists of an in situ atmospheric sensor mounted on commercial aircraft for data gathering. It collects information similar to that collected by radiosondes carried aloft by weather balloons. It was developed by AirDat LLC, which was acquired by Panasonic Avionics Corporation in April 2013 and operated until October 2018 under the name Panasonic Weather Solutions. It is now owned by FLYHT Aerospace Solutions Ltd. In response to a government aviation safety initiative in the early 2000s, NASA, in partnership with the FAA, NOAA, and private industry, sponsored the early development and evaluation of a proprietary multifunction in situ atmospheric sensor for aircraft. The predecessor to Panasonic Weather Solutions, AirDat (formerly ODS of Rapid City, SD), located in Morrisville, North Carolina and Lakewood, Colorado, was formed in 2003 to develop and deploy the Tropospheric Airborne Meteorological Data Reporting (TAMDAR) system based on requirements provided by the Global Systems Division (GSD) of NOAA's Earth System Research Laboratory (ESRL), the FAA, and the World Meteorological Organization (WMO). The TAMDAR sensor was originally deployed in December 2004 on a fleet of 63 Saab SF340 aircraft operated by Mesaba Airlines in the Great Lakes region of the United States as a part of the NASA-sponsored Great Lakes Fleet Experiment (GLFE). Over the last twelve years, equipage of the sensors has expanded beyond the continental US to include Alaska, Caribbean, Mexico, Central America, Europe, and Asia. Airlines flying the system include Icelandair, Horizon (Alaska Air Group), Chautauqua (Republic Airways), Piedmont (American Airlines), AeroMéxico, Ravn Alaska, Hageland, PenAir, Silver Airways, and Flybe, as well as a few research aircraft including the UK Met Office BAe-146 FAAM aircraft. Recently, an installation agreement has been reached with a large Southeast Asian airline as well. The TAMDAR system has been in continuous operation since initial deployment in December 2004. In 2014 TAMDAR data began being implemented in the national mesonet program consisting of NOAA and its partners. TAMDAR observations include temperature, pressure, winds aloft, relative humidity (RH), icing, and turbulence that are critical to both aviation safety and the operational efficiency of the U.S. National Airspace System (NAS) and other world airspace management systems as well as other weather-dependent operational environments such as maritime, defense, and energy. Additionally, each observation includes GPS-derived horizontal and vertical (altitude) coordinates, as well as a time stamp to the nearest second. With a continuous stream of observations, TAMDAR provides higher spatial and temporal resolution compared to the Radiosonde (RAOB) network, as well as better geographic coverage, and a more complete data set than sent over Aircraft Communication Addressing and Reporting System (ACARS), which lacks RH, icing, and turbulence.