How Flying into the Middle of Hurricanes Began as a Bet

 

How Flying into the Middle of Hurricanes Began as a Bet

Out of approximately 23,000 operational business jets in the world, this Gulfstream-IV business jet is arguably the most important one.

You see, this jet plane is not just giving rides to CEO’s and celebrities.

Instead it is filled with scientists. The scientists who not only save lives, but also save tens of millions of dollars for the American taxpayers each year.

Owned by the National Oceanic and Atmospheric Administration, or NOAA, this jet's primary mission is to fly into hurricanes, as frequently as twice a day, during the Atlantic hurricane season. Hurricanes form over oceans and while satellites can detect and track them, they cannot predict their movement.

 

But more importantly, satellites cannot determine either the interior barometric pressure or the maximum sustained wind speeds at the surface, meaning that satellites cannot figure out how bad the hurricane actually is! The only way to get this information is to measure it inside the hurricane, inside the eye. Why use airplanes to do this?

Well, you wouldn’t want to send a ship into the eye of a hurricane. Not only would it be incredibly slow, but almost certainly deadly.

 

And you don’t really want to wait for the hurricane to pass over you to do your measurements, because by that point it would be too late. So the only viable option is to fly an aircraft into the hurricane. But why out of all commercial airplanes, only a business jet is capable of certain types of hurricane reconnaissance missions, why only a turboprop plane can fly into the eye of a hurricane while moving exactly at 210 knots, and how this all started with a dare, is Not What You Think.

 

How the Hurricane Hunters came to be back in 1943, as the Surprise Hurricane was approaching Texas, the US Army Air Force began evacuating their AT-6 Texan trainer aircraft from the Bryan Air Force base. This was noticed by British pilots who were being trained there by the Americans, which later started poking fun at their instructors, stating that the American aircraft lacked structural integrity.

The flying school commander, Colonel Joseph Duckworth, couldn’t take it anymore and bet his British students that he could fly into the middle of the hurricane and return intact. And he did! But only to immediately fly back into the eye of the hurricane for a second time, this time with the air base's weather officer, to measure temperatures within the storm.

 

And that is how the US Air Force began collecting data on hurricanes.

Three years later, in 1946, the term “Hurricane Hunters” was coined for the air force pilots who flew weather reconnaissance missions into the hurricanes. Today, the Hurricane Hunter duties are performed by both NOAA and the 53rd Weather Reconnaissance Wing of the US Air Force Reserve.

 

The NOAA hurricane hunter’s fleet consists of 2 WP-3D aircraft which are nicknamed “Miss Piggy” and “Kermit”, and also “Gonzo” - a Gulfstream - IV business jet. Fun fact, Miss Piggy got her name as she suffered from years of cosmetic neglect, being referred to as “the pig of the fleet”.

After some TLC that restored the aircraft to her former glory, she was named Miss Piggy. Meanwhile, the 53rd Weather reconnaissance wing has 10 WC-130 aircraft and 20 aircrews that perform hurricane surveillance missions. The Hurricane Hunters can conduct up to 5 sorties per day and provide 24-hour day continuous operations with the ability to fly into up to 3 storms at the same time. Typical hurricane hunters’ mission lasts between 8 to 10 hours, with about 6 hours on station.

 

Frequently, Air Force and NOAA Hurricane Hunters make rotational flights to hurricanes to have constant data flowing into the forecast models. In fact, flying into the hurricane non-stop is the only way to feed the weather models How Hurricane Hunters improve the weather forecast with the required data to make accurate predictions about the strength and the movement of a hurricane.

 

The Gulfstream business jet alone can improve the short term forecast accuracy up to 25%. And it has been doing so since 1997. Combine the business jet data with WP-3D Orion’s and WC-130s that fly directly into the eye of a hurricane and you get an additional 30% improvement in hurricane track accuracy. But to be clear, the forecast accuracy comes primarily from deploying drop sounds, a practice that began in the mid-1980s. Anywhere between 20 to 40 drop sounds are deployed during every mission.

They measure temperature, humidity, wind speed and direction.

 

The data is collected and transmitted in real-time to the national hurricane center via a satellite link for further processing, all while the drop sounds descend to the surface with the help of a parachute. What happens to the drop sounds?

They are mostly biodegradable. The increased accuracy in the hurricane forecast track gives advance warning to vulnerable population centers to prepare for the storm.

 

It also saves a lot of money. Reducing the forecast error by 25% means reducing the warning area, which means millions of people won’t have to be evacuated unnecessarily. This saves public agencies tens of millions of dollars.

Besides drop sounds, hurricane hunters are also starting to deploy drones that can fly into more dangerous parts of the hurricane. This will provide additional data which works hand in hand with the data gathered from the drop sounds. Hurricane Hunter aircraft are also equipped with powerful radars.

 

The business jet is equipped with a tail Doppler radar and the Orion is equipped with both tail radar and a lower fuselage radar

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The idea is to look at a hurricane like it’s a piece of cake, and by that, I don’t mean “easy”, but to see all the layers that the hurricane is made of. Additionally, the Orion’s are equipped with Stepped Frequency Microwave Radiometers which help measure surface level wind speed and the rate of rain in hurricanes. But why does NOAA fly two distinct aircraft into a hurricane? Each aircraft has a different mission. The mission of WP-3Ds and WC-130s is to find and measure the exact center of the storm, which involves flying inside the eye of the hurricane. Both aircraft fly in an alpha pattern at 8 to 10 thousand feet, which is about one third of the way between the surface and top of the storm. They penetrate the eye of the hurricane multiple times during a single mission.

 

Each penetration is referred to as “penny”, and any hurricane hunter that reaches 300 penny flights, will become a member of the small and exclusive “300 club”. In contrast, the business jet flies much higher, over the storm, as well as in front and around it while collecting data on how the surrounding weather affects the hurricane track.

 

The data collected by the Gulfstream drop sounds is mostly used by forecast models to predict which direction the hurricane will go, while the propeller aircraft are mostly used to figure out how bad the storm actually is. What is like to fly inside a hurricane?

According to the pilots, flying through a hurricane is like riding a roller coaster through a car wash! But every storm is different and has its own personality, which is why each one gets a different name.

 

Sometimes you can have extreme turbulence, and other times it's the smoothest ride.

Imagine a table top, the faster it spins, the more stable and symmetrical it is. That is a category 5 hurricane. But as it starts to slow down, or lose its intensity, it starts to wobble, and that really determines how rough of a ride it will be. Another fun fact: no hurricane in the Atlantics has ever been named Chuck, in the fears that it would destroy everything! All three hurricane hunter aircraft also have a nose radar that is primarily used for safety of the aircraft.

 

It helps pilots avoid flying through dangerous parts of the hurricane. The crew don't mind flying through the red areas on the radar, but they want to avoid magenta, which means heavier rain and more turbulence. Flashing white means severe turbulence. With smaller hurricanes, if there’s a bad cell, the aircraft would fly around it. But with category 4 or category 5 hurricanes, it's a 360 degree eye wall, so there’s no way to avoid it.

The aircraft has to fly through it. Flying an aircraft in the middle of a hurricane, with varying wind speeds, updrafts and downdrafts is a very different operation from flying a regular commercial jet.

 

When it gets too turbulent, the autopilot will disengage, and the plane has to be operated manually. This can get stressful and tiring for a pilot which is why NOAA’s Orion airplanes have three pilots onboard. Two pilots are flying, while the third one rests in the rack behind. NOAA’s business jet also frequently employs a third pilot during night time surveillance missions. Besides the three pilots on the Orion, there’s also a flight engineer who sits between two pilots. The pilot on the left makes sure that aircraft is following the proper flight path and altitude. Meanwhile, the pilot on the right monitors the whole operation, handles all the communications with the rest of the crew and backs the other pilot.

 

The flight engineer is responsible for the aircraft speed, constantly adjusting engine power levers from max power to idle in mere seconds. This is not how one would normally fly this aircraft, but in a hurricane, you have no other choice. The speed and direction of winds change incredibly fast. If airspeed drops to 200 knots while at max power, that is too slow, so the pilot has to pitch down to gain more speed … or risk stalling the aircraft. On the flip side, flying too fast can put too much G-forces on the aircraft, and it's also too turbulent.

 

The flight engineer’s goal is to keep the airspeed at exactly 210 knots, which is not too fast nor too slow. Why are business jets perfect to fly into hurricanes? But it makes you wonder: why fly a business jet into a hurricane? Why not use one of the existing turboprops instead, or a P-8 Poseidon which is essentially a Boeing 737 passenger jet?

The issue with turboprop engines is that they cannot fly high enough.

The Orion and the WC-130 both max out at about 28,000 feet. Same with commercial jets. They fly at 30,000 to 40,000 feet, and there are good reasons for that.

Jet engines operate most efficiently at higher altitudes, because the air is much thinner at 30,000 feet compared to ground level.

 

But if you climb too high, over 40,000 feet, the air becomes too thin for the engine to produce enough thrust and for wings to generate sufficient lift. Another consideration for commercial jets, is the “time of useful consciousness” or TUC, which refers to how long a person would remain conscious in case of a cabin decompression.

 

At an altitude of 35,000ft, TUC is between 15 to 30 seconds, while at an altitude of

50,000ft, TUC is reduced to just five seconds, which is not enough time for passengers to put on their oxygen masks. Military airplanes can fly higher than commercial jets, for example the famous U-2 spy plane can reach altitudes of 73,000 feet. But it would be too small to carry all the meteorological equipment. Now the B-52 Stratofortress can fly as high as 50,000 feet, but whenever it flies above 43,000 feet, its range is severely diminished. Not to mention that it would be impractical to reconfigure that plane for weather reconnaissance. The remaining option is business jets, which believe it or not can fly as high as 51,000 feet. In the case of NOAA’s Gulfstream-IV business jet, it can cruise at 45,000 feet, right over the hurricane, which is perfect for high altitude surveillance.

 

The gulfstream samples the upper and lower level hurricane winds, since those affect the hurricane’s movement. Furthermore, deploying drop sounds from 45,000 feet, can produce a complete picture of the hurricane, since it takes 15 minutes for drop sounds to descend from the top to the bottom. But how come business jets can fly so high?

 

If you guessed it’s because flying at higher altitudes means less air traffic congestion, so rich people can get to their destination faster … you are wrong! The reality is that business jets have larger engines relative to their smaller size, and that’s what allows them to cruise at higher altitudes. Why only turboprops can fly into the eye of a hurricane?

But why are turboprops used to fly into hurricanes, and not turbofan airplane?

The eye wall of a hurricane is basically non-stop rain!

It's the largest amount of rain you can imagine in the atmosphere, like a literal carwash.

 

If you fly a turbofan through it, the engine is more likely to flameout due to the massive amounts of water ingested. In contrast, the propeller in front of a much smaller ingestion intake on a turboprop engine, keeps a lot of the water from coming into the engine compressor chamber. The second reason is that when it comes to power throttling, turboprops respond more quickly compared to turbofans. Turbofan engines have a 1 to 2 second delay, since it takes time for the engine to spin up. In contrast, the thrust from a propeller can be adjusted by changing the pitch of the propeller blades, without having to change the engine RPM. This allows for near instantaneous ability to throttle up or down, which is especially useful when trying to fly at the constant speed of 210 knots in a turbulent environment.

 

Finally, turboprops are more efficient at lower speeds compared to turbofans.

Flying at lower speeds through the eye wall of a hurricane results in less stress on the airframe.

 

It also allows the hurricane hunters to spend more time inside the eye, in order to collect the necessary measurements. All this said, is it actually safe to fly through the middle of a hurricane? How safe is it to fly inside a hurricane? Since the inception of the hurricane hunters, 6 aircraft have been lost while flying into hurricanes.

The last incident occurred on October 12th, 1974, when a WC-130 flew into Typhoon Bess and lost radio contact. The aircraft was never found, and all six crewmembers were listed as killed in action.

 

There are definitely risks involved in flying into the middle of a hurricane, especially if it's your full time job. To the people who put their lives on the line in order to provide us with accurate information on incoming hurricanes, “thank you”.

 

As early as 2024, The NOAA’s Gonzo business jet is expected to be replaced with a Gulfstream G550 which can fly even higher at 51,000 feet.

As for Miss Piggy and Kermit, they are planned to be retired after 2030 with a turboprop replacement. And with regards to WC-130s, I guess they will just fly forever.