Safety Recommendation A-20-016

We note that, in response to Safety Recommendation A-20-16, the FAA and National Oceanic and Atmospheric Administration’s National Severe Storms Laboratory are working on an enhancement to the Graphical Forecasts for Aviation – Low Altitude (GFA-LA), formerly the HEMS Weather Tool, that would add continuous TDWR data to the Multi-Radar/Multi-Sensor System mosaic. We also note that, in response to Safety Recommendation A-20-17, you are continuing to work with the NWS to incorporate into the GFA-LA the Next Generation Weather Radar 0- to 4 kilometer above-ground-level reflectivity capability, which will gray out any areas without coverage.

Although we believe the ongoing work that you described is responsive to both safety recommendations, we urge you and the NWS to seek feedback from the pilot community on your plan to gray out areas without weather radar coverage and address any concerns they may have.

Pending completion of the improvements to the GFA-LA (in place of the HEMS Weather Tool, as specified in these recommendations), the Board has voted to keep Safety Recommendations A-20-16 and -17 classified OPEN-- ACCEPTABLE ALTERNATE RESPONSE.

Footnote: Safety Recommendation A-20-19 asks the NWS to add TDWR data to the HEMS Weather Tool overlay (as recommended in Safety Recommendation A-20-16 to the FAA). This recommendation is currently classified Open—Acceptable Alternate Response. Safety Recommendation A-20-20 asks the NWS to provide capability in the HEMS Weather Tool to graphically display areas of weather radar limitations, including areas where beams may lack low-altitude coverage, areas that lack radar coverage, and areas of beam blockages (as recommended in Safety Recommendation A-20-17 to the FAA). This recommendation is currently classified Open—Acceptable Alternate Response.

-From Bryan Bedford, Administrator: In response to the National Transportation Safety Board’s request in their letter dated April 24, 2025, the National Severe Storms Laboratory (NSSL) developed NEXRAD 0-4 km above ground level (AGL) composite reflectivity mosaic. However, when operating this experimentally, NEXRAD 0-4 km AGL would not have detected the snow showers that were occurring at the accident site because the nearest Weather Surveillance Radar,1988 (WSR-88D), overshot the snow showers.

The National Oceanic and Atmospheric Administration’s NSSL has proposed incorporating Terminal Doppler Weather Radar (TDWR) data into the Multi-Radar/Multi-Sensor (MRMS) system mosaic. The development and testing of software to read in and use the TDWR data will be a multi-year effort due to complicating factors, including limitations of the MRMS reflectivity computation methodology, differences in WSR-88D and TDWR wavelengths and power modes, TDWR vertical gap issues, and quality control challenges.

There is currently no estimated date for when the TDWR data will be implemented in MRMS or the graphical forecasts for aviation low altitude (GFA-LA), formerly known as the Helicopter Emergency Medical Services (HEMS) tool.

We note that, in cooperation with the NWS, you continue to investigate a prototype Next Generation Weather Radar (NEXRAD) capability that has a 0- to 4-kilometer, above-ground-level reflectivity radar mosaic; may provide better low-level detail than current radar mosaic products; and includes alerts to identify areas without coverage. Although you had initially planned to incorporate the new NEXRAD low-altitude mosaic in the HEMS Weather Tool, that tool has been integrated into the interactive Graphical Forecasts for Aviation – Low Altitude (GFA-LA), which is located at aviationweather.gov.

It is our understanding that you intend to include the new NEXRAD capability in the GFA-LA and anticipate completing that work in calendar year 2026.

Regarding Safety Recommendation A-20-16, we believe NEXRAD’s low-level radar mosaic could be an adequate replacement for TDWR data; however, for us to make that determination, the FAA needs to show us that the new NEXRAD low-altitude mosaic would have been effective in this accident. Specifically, we would like to know if the snow showers that were occurring at the accident site would have been detected by the new NEXRAD capability and displayed on the GFA-LA. In the meantime, we encourage you to continue including TDWR in the GFA-LA.

Regarding Safety Recommendation A-20-17, we believe including alerts in the GFA-LA about areas without coverage would satisfy the intent of this recommendation.

We point out that both safety recommendations specify changes to the HEMS Weather Tool, which is no longer available and has been integrated into the GFA-LA. We believe your ongoing work with the NWS to evaluate NEXRAD are positive; however, because any future improvements would be made to the GFA-LA (instead of the HEMS Weather Tool), they would represent an acceptable alternative solution to these safety recommendations. Accordingly, pending our review of the requested information and completion of the recommended actions, the Board has classified Safety Recommendations A-20-16 and -17 OPEN-- ACCEPTABLE ALTERNATE RESPONSE.

-From Michael G. Whitaker, Administrator: The Federal Aviation Administration (FAA) met with the National Transportation Safety Board (NTSB) on April 13, 2023, and discussed other possible solutions to address the intent of these safety recommendations. The FAA and the NWS are investigating the use of a prototype Next Generation Weather Radar (NEXRAD) capability developed by the National Severe Storms Laboratory (NSSL) as a possible alternative to address Safety Recommendations A-20-16 and -17.

The NEXRAD prototype provides a 0-4 kilometer above ground-level reflectivity radar mosaic that may provide better low-level detail than current radar mosaic products and includes alerts to identify areas without coverage. The NTSB meteorologists are collectively studying all these merits as well as the potential for the prototype to provide a quicker path to operations.

The next steps are user assessments to be conducted by the Aviation Weather Center Testbed and the FAA’s Aviation Weather Demonstration and Evaluation services team to evaluate the prototype from a Human Factors standpoint to ensure that users understand the changes and interpret the product correctly before it is implemented into the operational Multi Radar Multi-Sensor (MRMS) operated and maintained by the NWS. The anticipated completion date for this work is September 30, 2026.

Although the FAA will continue integrating TDWR into MRMS, we believe the new 0-4 km NEXRAD capability may be a much better solution to these safety recommendations and will continue to collaborate with both NTSB and NWS meteorologists concerning this option.

I anticipate providing an update to Safety Recommendations A-20-16 and -17 by April 30, 2025.

We note that a working group that includes representatives from the FAA and the National Oceanic and Atmospheric Administration (NOAA) has recommended integrating TDWR data into the NWS’s Multi-Radar/Multi-Sensor (MRMS) system. We also note that you have contracted with NOAA to develop an enhancement to the HEMS Weather Tool that would use continuous TDWR data to create a radar mosaic with three-dimensional TDWR data and Next Generation Weather Radar (NEXRAD) information, and that the NWS is planning to display this information at aviationweather.gov.

In addition, you reported that the NWS is planning to evaluate a potential replacement for the current HEMS Weather Tool reflectivity that provides a 0-4 kilometer above-ground-level reflectivity radar mosaic and includes alerts or flags to identify areas without coverage.

We believe the working group’s proposed plan is responsive to both Safety Recommendations A-20-16 and -17. Pending our receipt of future updates and completion of the recommended actions, these recommendations remain classified OPEN-- ACCEPTABLE RESPONSE.

-From Billy Nolen, Acting Administrator: The Federal Aviation Administration (FAA) continues to work jointly with the NWS to address Safety Recommendations A-20-16 and -17 and companion Safety Recommendations A-20-19 and -20, which are assigned to the NWS. The FAA-NWS Working Group continues to meet to coordinate how best to address these recommendations.

As stated previously, to address Safety Recommendation A-20-16, the FAA determined that the best course of action would be to pursue integrating Terminal Doppler Weather Radar (TDWR) data into the NWS’s Multi-Radar/Multi-Sensor System in a seamless, transparent manner. The FAA’s Aviation Weather Research Program has contracted with the National Oceanic and Atmospheric Administration’s (NOAA) National Severe Storms Laboratory (NSSL) to conduct this work. Contractual issues between the FAA and NOAA delayed the start of the work, which was expected to commence in the summer of 2022. Those contractual issues have been addressed, and NSSL is ready to begin the integration.

However, this is not a trivial effort due to differences in the TDWR and the operational Next Generation Weather Radar (NEXRAD). Development of the integrated capability is expected to be a one-year effort followed by quality assessments and user evaluations. The resulting radar mosaic will integrate three-dimensional TDWR information with NEXRAD information to be displayed by the NWS at aviationweather.gov.

Safety Recommendation A-20-17 will ultimately be addressed by the abovementioned integrated capability. In the interim, NSSL has a prototype capability using NEXRAD information that is a potential replacement for the current Helicopter Emergency Medical Services Tool reflectivity (the radar at lowest altitude). This prototype provides a 0-4 km above ground level reflectivity radar mosaic. It also includes alerts to identify areas without coverage. This prototype will be provided to the NWS for evaluation as a possible initial upgrade that will eventually be subsumed by the integrated capability.

We will continue to work with the NWS to determine additional activities and timelines for operational implementation and remain on schedule to complete these activities by December 2025.

I will keep the Board informed of the FAA’s progress on these recommendations and provide an update by April 30, 2024.

-From Billy Nolen, Acting Administrator: The Federal Aviation Administration (FAA) continues to work jointly with the NWS to address Safety Recommendations A-20-16 and -17 and companion Safety Recommendations A-20-19 and -20. The FAA-NWS working group has met several times since 2020 to coordinate how best to address these recommendations. The FAA and the NWS also met with the Board on March 17, 2021, to discuss several options to meet the intent of these safety recommendations.

To address Safety Recommendation A-20-16, the FAA determined that the best course of action would be to pursue integrating Terminal Doppler Weather Radar (TDWR) data into the NWS’s Multi-Radar/Multi-Sensor (MRMS) system in a seamless, transparent manner. The FAA’s Aviation Weather Research Program has been funding a project conducted by the NWS’s National Severe Storms Laboratory (NSSL) for several years to integrate TDWR data into the MRMS system, so significant progress has already been made on this endeavor. In this case, no separate step/selection would be needed since the TDWR data would be turned on all the time.

The resulting radar mosaic will integrate three-dimensional TDWR information with Next Generation Weather Radar information to be used in the HEMS Tool at aviationweather.gov. The differences in the output between the two types of weather radar make the merging non-trivial.

To address Safety Recommendation A-20-17, the NSSL is already developing the capability to replace the current HEMS reflectivity (the Radar at Lowest Altitude) with a 0-4 km above ground level reflectivity radar mosaic. This will include alerts or flags to identify areas without coverage.

The NSSL development of the radar mosaic commenced during the Summer of 2022, which will build on the above-mentioned project funded by the FAA. Initial development will be a one-year effort, followed by quality assessments and user evaluations taking an additional 6-10 months. We will continue to work with the NWS to determine additional activities and timelines for operational implementation into the HEMS Tool following the NSSL development and anticipate completion of these activities by December 2025.

I will keep the Board informed of the FAA’s progress on these recommendations and provide an update by February 28, 2023.

You reported that representatives from the NWS and FAA have agreed to form a joint working group to address these recommendations. We note that you are currently working with the NWS to identify work group participants from other government agencies who are familiar with TDWR and the HEMS weather tool.

We believe your planned working group is a necessary first step toward responding to these recommendations. Pending our receipt of future updates and completion of the recommended actions, Safety Recommendations A-20-16 and -17 are classified OPEN--ACCEPTABLE RESPONSE.

-From Steve Dickson, Administrator: At the joint FAA-NWS interagency meeting held on June 18, 2020, representatives agreed to form a joint FAA-NWS working group to coordinate and address these safety recommendations. Both the FAA and the NWS are currently identifying work group participants, and representatives from other government agencies involved with TDWR and HEMS will also be identified and invited to participate. We anticipate the first working group meeting will occur before the end of Fiscal Year 2020.

We envision there will be more substantial virtual meetings planned over the next several months to address requirements and research that will be identified for any implementation in regards to these recommendations.

I will keep the Board informed of the FAA’s progress on these safety recommendations and provide an update by September 30, 2021.

The attached letter from the NTSB Chairman provides information about the NTSB’s May 19, 2020, report Helicopter Air Ambulance Collision with Terrain, Survival Flight Inc., Bell 407 Helicopter, N191SF, near Zaleski, Ohio, January 29, 2019, NTSB/AAR-20/01. The details of this accident investigation and the resulting safety recommendations may be found in the attached report, which can also be accessed at http://www.ntsb.gov. For more information about NTSB and our recommendation process, please see the attached one-page summary.

The NTSB is vitally interested in these recommendations because they are designed to prevent accidents and save lives. We would appreciate a response within 90 days of the date of this letter, detailing the actions you have taken or intend to take to implement these recommendations. When replying, please refer to the safety recommendations by number (for example, A-20-13 and -17). We encourage you to submit your response to ExecutiveSecretariat@ntsb.gov. If your reply exceeds 20 megabytes, including attachments, please e mail us at the same address for instructions on how to send larger documents. Please do not submit both an electronic copy and a hard copy of the same response.

This letter provides information about the National Transportation Safety Board’s (NTSB) May 19, 2020, report Helicopter Air Ambulance Collision with Terrain, Survival Flight Inc., Bell 407 Helicopter, N191SF, near Zaleski, Ohio, January 29, 2019, NTSB/AAR-20/01. The details of this accident investigation and the resulting safety recommendations may be found in the attached report, which can also be accessed at http://www.ntsb.gov.

As a result of this investigation, the NTSB identified the following safety issues:

• Survival Flight’s lack of comprehensive and effective flight risk assessment and risk management procedures. • The lack of a positive safety culture endorsed by Survival Flight management and the lack of a comprehensive safety management system. • Need for flight data monitoring programs for helicopter air ambulance (HAA) operators. • Lack of HAA experience for principal operations inspectors assigned to HAA operations. • Lack of accurate terminal doppler weather radar data available on the HEMS (helicopter emergency medical services) Weather Tool. • Lack of a flight recorder.