For Paulus, an Eritrean refugee in northern Ethiopia, a helicopter is not only an aircraft people can spot above in the sky, but also a form of torture where victims are forced to balance on their belly with hands and feet tied together and legs bent behind their back.
And the evangelical Christian said he knows the helicopter well because, he claims, he was tied in that position for 136 hours in an effort to pressure him to recant his faith.
They kept asking me to sign a document, he told BBC News in a report last week, and agree to not participate in church activities or express my faith in any form. I was told I would be untied and released the minute I agreed to their requests.
Sitting in Shimelba refugee camp close to the border of Eritrea, Paulus told of different torture techniques he endured in his homeland for being an evangelical Christian.
He is among a growing number of Eritrean Christians fleeing the country to escape religious persecution. Inside Shimelba refugee camp where Paulus lives is the Ebenezer Evangelical Church where he and others like him can worship freely without fear of persecution unlike back home.
Eritrea, a small country in East Africa on the Red Sea, is one of the worst persecutors of Christians in the world. The government is highly suspicious of newer Christian movements such as the Evangelical and Pentecostal churches and frequently harasses their followers. A harsh crackdown began five years ago on all churches outside of the government-approved Orthodox, Catholic or Lutheran denominations
There are an estimated 2,000 Eritrean Christians under arrest without trial or legal charge for the sole reason of their religious beliefs, according to Compass Direct News, a Christian news agency that reports exclusively on persecution of Christians. Eritrean security forces raid weddings, baptism, worship services, prayer meetings, and other religious gatherings and arrest both hosts and guests.
College-educated Samuel (not his real name), 24, was arrested in 2005 along with 19 other people while attending a friends wedding ceremony. After he was imprisoned, Samuel was forced to perform backbreaking manual labor for the next 12 months and regularly beaten, according to BBC.
One of the tortures he had to endure involved being hung from a tree with his arms stretched in the form of a crucifixion for three days.
They asked me if I would like to leave [my faith]. They asked every night for four months, he told BBC News.
Other tortures faced by Christians include being held in metal shipping containers under the hot sun, beatings, and deprivation of food.
Eritrea also recently cracked down on the Orthodox Church, which it previously had a close relationship.
The head of the Eritrean Orthodox Church former Patriarch Abune Antonios, 80 was illegally dismissed from his position in January 2006 after criticizing the government for interfering in church activities and for its persecution of evangelical churches, according to human rights group Amnesty International. For nearly two years he has been under stringent house arrest with little news heard about his condition in the past few months.
The U.S. Commission on International Religious Freedom in May recommended that Eritrea be re-designated by the State Department as one of the 11 countries of particular concern (CPCs) for 2007. The U.S. Department of State for three straight years has designated Eritrea as a CPC the worst religious freedom violation label.