The Federal Aviation Administration is the latest government agency to shift its e-mail systems to the cloud.

The FAA has awarded a $91 million contract to the Computer Sciences Corp. to implement Microsoft’s Office 365, which includes e-mail, instant messaging and Web-conferencing capabilities, CSC and Microsoft announced Thursday. Sixty thousand FAA employees and 20,000 Department of Transportation employees will make the migration.

Last month, the Interior Department awarded a $35 million contract to Onix Networking Corp.of Lakewood, Ohio, to shift it to a Google-supported cloud e-mail service.

The General Services Administration and the Agriculture Department migrated to the cloud in 2011.

In 2010, the White House implemented a cloud-first policy to streamline many government computing functions. Cloud services are often more efficient and more secure than computing handled in-house, said Steven Van Roekel, the U.S. chief information officer, in an interview this week.

On Wednesday, the GSA rolled out a basic security standard that companies would have to meet before providing cloud services to federal agencies. The Federal Risk and Authorization Management Program, known as FedRAMP, provides for accredited third party assessment organizations that will verify whether companies meet the basic security requirements.

FedRAMP lists more than 160 such requirements.