To most people, hurricanes are to be avoided at all cost. The thought of intentionally flying an airplane directly into a hurricane is quickly dismissed as a very bad idea. Yet there are small groups of aircrew and scientists who regularly board planes that will not only but will spend hours crisscrossing it in order to get a better idea of what the storm will do next.

Hurricane Irma is one of the most powerful Atlantic hurricanes ever recorded and has plowed its way across the Caribbean this week. Irma has turned what once was beachside paradises into mostly uninhabitable stretches of land. and have suffered catastrophic damage, including to ports and airports, that will only hamper relief efforts. Unfortunately, much of Florida is now next for Irma and damage is expected to be catastrophic. Mass evacuations have been ordered for large areas of the state.

Like Hurricane Harvey before it, Irma has had a constant stream of aircraft flying in and out for several days as the planes gathered scientific data that cannot be obtained by satellites. Both the Air Force and the National Oceanic and Atmospheric Administration fly the aircraft that perform these missions.

The Air Force owns 10 WC-130Js and are all based at Keesler Air Force Base in Mississippi and assigned to the 53rd Weather Reconnaissance Squadron, which is part of the Air Force Reserve Command. (Keesler AFB is no stranger to hurricanes, suffering in damage from Hurricane Katrina.) The WC-130J is not much different than a normal J-model Hercules. No structural reinforcement has been provided. The only differences being the full-time addition of external fuel tanks to provide greater range and a radiometer on the starboard (right) wing. The is the primary tool used to determine a hurricane’s intensity. Typically, each WC-130H mission into a hurricane lasts nearly 11 hours and cover over 3,500 miles.

NOAA flies three aircraft to survey the hurricanes, named Kermit, Miss Piggy and Gonzo, with each wearing artwork depicting the . Gonzo is a Gulfstream IV-SP which does not fly into the hurricanes. Instead it flies around and above the hurricanes, usually at altitudes of 41,000 to 45,000 feet. Miss Piggy and Kermit are WP-3D Orions and are the penetrating assets of NOAA. Currently only Kermit is actively flying as Miss Piggy is being re-winged.

On Monday, three aircraft could be seen flying near and within Irma. One WP-3D, the Gulfstream and one WC-130J each had made observation flights of the storm and the flight paths provided a unique look at how they approach obtaining information.

For the WC-130J, they perform what is an Alpha Pattern. The plane will penetrate the storm from one “corner,” and will visit all four corners of the storm as it collects data. Depending on the size of the hurricane, the plane usually passes though the eye about every two hours. Hurricane hunters fly as high as 10,000 feet as they make multiple passes through the storm. They use a criss-cross pattern to fully analyze every quadrant of the hurricane, looking for an accurate depiction of the hurricane’s internal structure. The data then gets input into computer models, improving projected track and intensity of the hurricanes.

While weather satellites track hurricanes’ paths, manned missions help collect data on a storm’s temperature, wind speeds and directions, and barometric pressure. The lower the barometric pressure a hurricane has, the stronger the storm can be. Irma had a recorded pressure of 915 millibars and the lowest since 2007.

Hurricane hunting began in 1943 when a brave United States Army Air Corps colonel made the first successful flight into the eye of a hurricane. As the Surprise Hurricane approached the Texas coast, Col. Joe Duckworth and a trusting navigator took off from Bryan Field, northwest of Houston, with the intention of flying into a hurricane and (hopefully!) returning. A seasoned pilot who was regarded as of his time, Duckworth made a bet with a group of British pilots that the combination of his navigation skills and the sturdiness of the would allow him to fly into the storm and return. The pilot and his navigator did indeed make the flight successfully and, upon arriving back at their home field, were met by the base’s weather officer, who, learning of the flight, wanted his turn to fly into a hurricane. The navigator got out of the plane, the weather officer got in, and Duckworth once again took off and for the second time that day pointed his AT-6 at the coming hurricane.

It goes without saying that flying into hurricanes and typhoons is a very dangerous business. Since Col. Duckworth made the first flight into a hurricane 74 years ago, thousands of flights have been able to get inside storms—taking a look and recording measurements—before getting out.

But not everyone: six planes and 53 lives have also been lost. Five of the accidents occurred in the Pacific while the planes were inspecting typhoons. The first was in 1945 in the South China Sea, when a Navy was lost, along with the seven crew members aboard. That plane is also the only one of the six where the . Between 1952 and 1958, four more aircraft were lost, with the one in the Atlantic crashing in 1955.

The last aircraft to be lost was an Air Force WC-130H, which belonged to the 54th Weather Reconnaissance Squadron, based in the Philippines. On October 12, 1974, the aircraft departed as “Swan 38" and made their way to Typhoon Bess, which was a Category 1 typhoon with 75 mph winds. After making one penetration of the storm, all communications were lost after the WC-130 went back into the typhoon. Six crewman died, and since the tragic accident, the name Bess was removed from any future names given to typhoons.

In 1950, published an article about flying into typhoons that elucidated many of the risks. Typhoon Beverly, for example, was a strong storm and the B-29 that would fly into it was a veteran of World War II. But the storm popped rivets loose, and the aerial camera was torn free as maps belonging to the navigator floated around the cabin. Lt. David W. Lykins, the pilot in charge, described the experience as such in the magazine:

It is impossible for me to describe accurately or to exaggerate the severity of the turbulence we encountered. To some it may sound utterly fantastic, but to me it was a fight for life. I have flown many weather missions in my 30 months with the 514th Reconnaissance Squadron. I have flown night combat missions in rough weather out of England, and I have instructed instrument flying in the States, but never have I dreamed of such turbulence as we encountered in Typhoon Beverly. It is amazing to me the ship held together as it did.

Today, the violent effects of a hurricane still shake planes quite severely. Earlier this week, NOAA released footage on Twitter from inside one of the WP-3D flights, showing that hurricane flights are not for the average commercial flier.

Both NOAA and the USAF use two different systems to measure the intensity of a hurricane: the “Smurf,” or the SFMR, and a , which is an expendable collection device.

The Smurf is an exterior addition to the aircraft and can measure winds beneath the plane as well as determine rainfall rates. This information allows structural details of the hurricane to be established, better allowing for more accurate intensity forecasts. The Smurf was too late to help predict the devastation of Hurricane Katrina, but with its arrival in 2007 to the fleet it was estimated by NOAA that the device would increase the accuracy of hurricane forecasts .

As the chart shows above, a dropsonde is released from the aircraft and measures pressure, temperature and humidity. Dozens of dropsondes are dropped on a single mission and are tracked by GPS as they fall through the hurricane under a parachute. The real time data is passed back to the aircraft and the accompanying meteorologists.

Irma is expected to make landfall in southeastern Florida sometime Sunday, though the exact time and location are still unknown. In the meantime, the Hurricane Hunters will continue flying in.

NOAA is scheduled to fly four missions on Friday, two with each aircraft. The Air Force will also fly more missions to try and determine that Irma is hopefully weakening in intensity. As the evacuations and emergency preparations are made, much of the information that lead to issuing these warnings and orders came from the crews who fly into hurricanes. By risking their own lives, they are able to save the lives of many others.