NAIROBI, Kenya — Sudan Airways regularly ranks among the worst airlines in the world. The national carrier has only one working plane, and it has suffered so many deadly accidents in recent years that passengers have acquired the habit of praying before takeoff.

The troubled airline, or rather, airplane, epitomizes some of the effects that two decades of American sanctions have had on Sudan, a predominantly Arab country on the edge of sub-Saharan Africa.

Since the 1990s, the United States has imposed a series of economic sanctions on Sudan over its government’s support of terrorist groups, including Al Qaeda, turning the country into a pariah state.

Most Western countries have shunned Sudan, making it hard for companies like Sudan Airways to procure parts or buy new planes from Boeing or Airbus. The airline’s general manager once described the sanctions as “hell.”