IN THE CENTER OF GUSTAV—You can feel it when this plane gets close to its destination. It dips, bumps and skips. The chatter on the radio turns from banter to business: barometric pressure, temperature, wind speed.

As one of only 10 specially equipped C-130 Hurricane Hunters, its mission is helping forecasters know where tropical storms and hurricanes will go and when.

On Wednesday, it was headed to 19 degrees north latitude, 74 degrees 18 minutes west longitude: the last known coordinates of the center of Tropical Storm Gustav, which was messily churning through the Caribbean.

The flight plan sounds straightforward: make a series of passes through Gustav’s winds, try to locate its center and quickly get the information back to forecasters at the National Hurricane Center in Miami.

Even today, satellites don’t get extremely accurate readings of what’s going on at the core of storms, says National Hurricane Center Director Bill Read. The sooner the center gets firsthand information from the plane, the better forecasters can predict a storm’s direction, size and intensity over hours and days. Air Force Reserve Hurricane Hunter flights operate around the clock when there’s a storm.

Flying in this $72 million aircraft is completely different from a commercial airliner. For visitors, it starts with a preflight warning about sudden drops.

“There have been a few people who have hit the ceiling unexpectedly,” says Lt. Col. Troy “Bear” Anderson, who headed Wednesday morning’s flight of 13 people.

Passengers strap into red fabric benches along the sides of the utilitarian cargo hold, where the unfinished ceiling is crisscrossed with bundles of white wires and tubes wrapped in pale green fabric blankets. The toilet is cordoned off by a green curtain. The motion-sickness bags assure those about to lose their lunches that “even veteran travelers are subject to occasional motion sickness.” At first glimpse, the storm’s center appears like a comma on the radar, a crescent of green and yellow. And the first pass is mild. “We’re going to chase this one a little bit,” says Maj. Brian Schroeder, one of three weather officers onboard.

Schroeder, who is completing his training, guides pilot Capt. Dena Schulz into what he believes is the center of the storm.

“Give me left 40,” Schroeder says on his headset, “As fast as you can whip it.”

“You’re going to nail it this time,” says Lt. Col. Valerie Hendry, the weather officer training Schroeder. When instruments tell Schroeder that the winds have shifted from battering one side of the plane to lashing at the other, Schroeder knows: We’re at the center of the storm.

Schroeder asks that the plane position be marked, and the flight’s loadmaster, Tech. Sgt. Troy Bickham, releases a package of instruments out of the plane. Called a dropsonde, it’s a cardboard tube about the length of one’s forearm and stuffed with sensors. For a few minutes before it hits the water, the dropsonde will relay data back to the plane, including wind direction, wind speed, air temperature, relative humidity and barometric pressure. “The wind speed and the barometric pressure haven’t changed much, so the storm hasn’t strengthened. Schroeder calls it “tropical trash,” but that doesn’t mean the danger has passed. “It’s almost like it’s gathering up its belongings here,” Schroeder says on one of the next passes through the storm, “like it’s wanting to be a hurricane again.”