Mr. Shirima’s rise to the top started after he left Air Tanzania, with close associates saying it was a long journey from owning a barbeque to becoming a truck driver and finally starting Precision Air in the 1990s.
Precision Air was incorporated in Tanzania in January 1991 as a private airline and started operations in 1993. At first, it operated as a private charter air transport company, but in November 1993, it changed to offer scheduled services to serve the growing tourist market.
In 2006, Precision Air became the first Tanzanian airline to pass the IATA Operational Safety Audit.
Reports show that, in addition to his aviation interests, Shirima owned five percent of the stock of I&M Bank (Tanzania), a medium-sized commercial bank. As of December 2011, the bank's total assets were valued at about US$130 million, and the bank's shareholders' equity was approximately US$15 million.
Shirima was also the founder and proprietor of Cornelius Ngaleku Orphanage, located in Useri Division, Rombo District, Kilimanjaro Region, in northern Tanzania.
The orphanage looks after homeless children picked up on the streets.