Judge restricts NOAA hurricane hunter jet

There is little worth mentioning in the tropics today. The tropical disturbance in the Gulf of Mexico has moved ashore into Texas. A strong tropical wave is approaching the Lesser Antilles Islands, but is under 30 knots of westerly wind shear that will prohibit development. A large area of cloudiness off the east coast of Florida is also under high wind shear. Tropical storm development in the Atlantic is unlikely for at least the next two days.

Judge restricts NOAA hurricane hunter jet
A federal labor judge ruled Friday that the high-altitude NOAA Gulfstream jet cannot fly into the core region of hurricanes any more. The judge ruled in favor of the NOAA's labor union, which argued that flying the jet into the core of a hurricane, even at high altitude where turbulence is generally light, posed an unacceptable risk to the crew.


Figure 1.The NOAA Aircraft Operations Center's Gulfstream IV jet, nicknamed "Gonzo" after the Muppets character, operates out of MacDill Air Force Base in Tampa, Florida. Image credit: NOAA.

The NOAA jet generally files at altitudes of 43,000 feet around the periphery of hurricanes, dropping dozens of dropsonde probes that fall on parachutes through the storm that radio back information on temperature, winds, pressure, and humidity. These measurements have been shown to improve track forecasts of hurricanes by as much as 25%, and are crucial to the Hurricane Center's operational forecasts. Generally, the NOAA jet avoids the central core area of a hurricane, where the potential for dangerous turbulence is highest. However, in 2003 the NOAA jet flew into the eye of Hurricane Fabian near Bermuda, by entering through a large gap in the eyewall. Flights into the core regions of Tropical Storm Emily and Franklin in 2005 were also performed, although in all these cases the aircraft was careful to avoid penetrating thunderstorms, and just flew through the high cirrus clouds of the Central Dense Overcast (CDO). Nevertheless, the union argued that such flights were too dangerous, and collected little valuable data.

The Gulf Stream IV jet is a much different king of aircraft than the low-altitude P-3 and C-130 hurricane hunter aircraft, which can shrug off the moderate turbulence one typically finds in hurricane clouds. Moderate turbulence poses a much higher risk to the Gulfstream IV jet, because is flies so much faster. Flying through CDO in the core region of a hurricane presents an increased risk of moderate turbulence, due to the presence of strong wave-like features that propagate through this region. I question whether this increased risk is worthy of causing a ban on all flights into the core region of a hurricane, because in nearly all cases this can be safely accomplished if the crew and pilot exercise good judgment. However, as a member of a crew that once exercised bad judgment in deciding to penetrate Hurricane Hugo's eyewall, I can certainly sympathize with the union's case.

While the new ruling will not significantly affect the Gulfstream IV jet's current ability to provide improved data in support of better hurricane forecasts, it may substantially affect its future role. An airborne Doppler radar system was due to be installed on the NOAA jet by 2009. Data from this radar would be of most value if the jet could fly into the inner core region of hurricanes. With the jet now restricted from going to where the radar data would be of most value, the plans for the new radar may have to be scrapped. This is not necessarily a bad thing, since the heavy new radar would substantially reduce the the flight altitude of the jet. This would significantly decrease the value of the dropsonde data, since the probes would not be able to sample the upper reaches of the storm any more. In the end, the union's victory may turn out to be a positive for all concerned.

Jeff Masters