Assessments of the Visual Flight Rules Not Recommended Statement

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Authors: Ulf Ahlstrom
Kevin Hallman
Nicole Racine

Ahlstrom, U., Racine, N. & Hallman, K. (2019). Assessments of the Visual Flight Rules Not Recommended Statement (DOT/FAA/TC-19/45). Atlantic City International Airport, NJ: FAA William Hughes Technical Center.



We evaluated the weather conditions that pilots and Flight Service Station (FSS) specialists deem important to determine whether Visual Flight Rules (VFR) Not Recommended (VNR) conditions are/will be present or not. In addition, this effort began to define criteria for an online weather planning VNR service.


One of the FSS specialist responsibilities is to evaluate the weather along a proposed route of flight and decide if conditions warrant a VNR statement. Some pilots view the VNR statement unhelpful due to perceived over application.


We provided a group of FSS professionals and a group of general aviation pilots with a series of scenarios representing different weather categories to assess how GA pilots and FSS specialists determined flight conditions (VNR or VFR) using standard weather products.


Based on the correlation analysis, we cannot conclusively identify the specific standard weather products used to make a VNR or VFR determination or any differences between participant groups in making that determination, however, we identified certain common products that participants rated as having a “moderate impact” or above.


Due to inconsistency and wide variation in weather product use, we find that there is a need for a procedure standardization.


If we can define and train FSS specialists (and pilots) to adopt a procedural method of evaluating the weather products, we could apply that same methodology for an automated procedure that always follows the same steps and make consistent recommendations.