The Challenge of Determining Weather Requirements for the FAA's Decision Support Systems

It's time to move beyond “an improved forecast” or “better weather products” as our requirements for weather information. It is often assumed that if we have these “better” products we will automatically have an improved response to weather events and increased system efficiency.

In order to do this, we must understand weather-related decision making, and specifically how those decisions will eventually be supplemented or even replaced by DSTs.

The DSTs of the future, as part of their binary calculations, will need to know some basic information, namely: A) When is the “optimal” time to make decision X for airport Y? B) What is the confidence level for this decision (probabilities)? C) What to do/how to react to the four different outcomes from the weather decision matrix (do something/nothing happens, do something/something happens, do nothing/nothing happens, do nothing/something happens).

Therein lies the challenge of determining weather requirements for the FAA's decision support systems. Improved weather forecasting and products are only a small piece of the overall equation. Determining the “sweet-spot” for weather-related traffic management decision making is a key element that is routinely overlooked.

Each weather-related traffic management decision has an associated timeline – e.g., if you make the call to implement a traffic management program 60 min out, that will allow enough time for X to take place. However, if the same decision is made at 25 min out, then you may still be able to do X, but you will likely have to deal with Y. If you decide at 5 min out (or as soon as the weather is actually impacting your area of concern) then X is no longer possible and you will have to do Z, P, and Q. Depending on the decision being made and when the sweet spot is for making that decision, then that is your basis for determining requirements for weather accuracy and timing.

In general, the requirements for weather-related decision making need to be more holistic and encompassing than simply looking to improve the response to NAS weather events via an “improved” forecast. Proactive decision-making and risk vs. gain assessments that allow the most efficient use of the airspace need to be included as an element of the overall requirements for weather.