357 Weather Product Latency Versus Data Age: Differences and Impacts on Aviation

Monday, 8 January 2018
Exhibit Hall 3 (ACC) (Austin, Texas)
Randall Bass, FAA, Washington, DC

Handout (4.0 MB)

There is sometimes confusion, especially among users, between weather product latency and data age. Weather products such as satellite imagery or radar mosaics of precipitation contain a valid time stamped on the product. This time stamp is usually the time the data within the product were processed or the time the product was actually produced and disseminated. Product latency is the length of time elapsed between the time stamp on the product and the time the product is viewed or used. Generally users comprehend product latency and take the difference into account. Less understood or considered by users is data age. Data age refers to how old the data is within the product. The actual data making up these products are rarely measured or collected exactly at those valid times indicated on the product, and may in fact be many minutes or even hours old. For example, while a radar mosaic image may have a valid time of 2016 UTC, the individual radar scans that make up that mosaic could be anywhere from 30 seconds to more than 15 minutes old. In most cases there is no way of knowing exactly how old the data is within a weather product.

The misunderstanding between product latency and data age has produced fatal consequences in aviation. The National Transportation Safety Board has documented several instances where pilots misinterpreted a radar image received in their cockpit via tablets or other devices. Basing their decisions on the time stamp of the product and not knowing the radar data was actually much older than the time listed, they inadvertently flew directly into thunderstorms with catastrophic results.

The Federal Aviation Administration, National Severe Storms Lab and others are researching ways for users to determine data age inside a product. Concepts such as allowing a user to move their curser over a pixel to display the age of the information or producing another product that illustrates data age are being considered. This presentation will describe the problem, explain the difference between product latency and data age, provide examples of the impacts of this matter on aviation, and detail efforts occurring to overcome this issue.

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