ANCHORAGE, Alaska >> Claire Richardson remembers taking off in an airplane uniquely configured for Alaska when a horrible smell seeped into the passenger area.

The captain soon came on the speaker to apologize for the odor, which was coming from 70 skittish baby reindeer headed for Texas.

“Guess they all pooped as we lifted off from the runway,” said Richardson, a Jesuit volunteer at a Nome radio station during the 1980s flight who is now chief of staff for Alaska Lt. Gov. Byron Mallott.

Those days will be coming to a close as the special plane that hauls people, goods and even animals on the same flight is taken out of service in a state with few roads.

Alaska Airlines is retiring its last four combi planes, special Boeing 737-400s designed to carry cargo in the middle of the plane and 72 passengers in the rear, company vice president Marilyn Romano said ahead of this week’s unveiling of the first of three new cargo planes for the state.

“They’ve been our workhorses,” said Jason Berry, manager of the company’s cargo division.

The new cargo planes are a dedicated fleet of three 737-700s, and they are the first ever to be converted from passenger jet to cargo planes. Passengers will now fly separately in 737-700s.

Alaska Airlines is the only major airline in the U.S. that had combi planes, which were designed for the special challenges of the nation’s largest state.

A postage stamp placed in the middle of an average sheet of paper represents the area a person can reach in Alaska by coast line, river, road or railroad.

“If you want to see or do business in any of the rest of that sheet of paper, you only have two choices: You can fly an hour or walk a week,” said Mark Ransom with the Alaska Aviation Museum in Anchorage.

The combi planes made sense to deliver people and goods to remote hub communities in Alaska in the most cost-efficient manner.

The planes can carry up to four large cargo containers — weighing anywhere from 12,000 to 14,000 pounds — in the middle of the plane. Passengers fill the rear of the plane, and they get on board by using stairs like the pre-jetway days.

“It’s bittersweet,” Romano said of the planes’ retirement, especially for those who understand what they have meant to the people of Alaska.

The planes usually fly to communities like Nome on the Bering Sea coast, Utqiagvik (formerly Barrow) on the northern Arctic Ocean coast or Deadhorse, the supply town for the Prudhoe Bay oil fields, where there might not be enough cargo for a full planeload or enough passengers to fill a jet.

From those locations, smaller airplanes usually deliver the cargo and passengers to dozens of nearby villages.

The combi planes also make famous milk runs through southeast Alaska, leaving Anchorage and stopping about every 45 minutes to deliver goods — including milk — to little communities before heading on to Seattle, where the airline is headquartered.

It’s not just milk that gets delivered. In other parts of the United States, cargo planes deliver durable goods to businesses to make commerce run, said Berry, the cargo division manager.

“In Alaska, we are carrying their milk, the groceries, the fruit, the vegetables, the pharmaceuticals, the drugs, for these people, for these communities,” he said.

And animals.

“Because of where we are and where we live, we have the opportunity to help move a lot of unique things, and a lot of them are living,” said Romano, the airline vice president.

That could include shipping an injured eagle to the Alaska Raptor Center in Sitka for rehabilitation or giving a lift back to Anchorage for scores of exhausted sled dogs that had just finished the nearly 1,000-mile Iditarod Trail Sled Dog Race in Nome.

The last combi flight is scheduled for Oct. 18, which is also the Alaska Day state holiday. This year marks the 150th anniversary of the formal transfer of Alaska from Russia to the United States. The final flight will deliver the combi plane to Seattle from Juneau.