#as-278

Planned launch: August 1967

Launch Vehicle: Saturn IB SA-207 and SA-208

Spacecraft: CSM-101 and LM-2

Prime crew:

-Commander: James Alton McDivitt

-Command Module Pilot: David Randolph Scott

-Lunar Module Pilot: Russell Louis "Rusty" Schweickart

Backup crew:

-Commander: Patten "Tom" Stafford CDR

-Command Module Pilot: John Watts Young

-Lunar Module Pilot: Eugene Andrew "Gene" Cernan

The mission number of AS-278, came from Saturn IB AS-207 and AS-208. It was also known as Apollo 3 and was planned as an D-type mission.

"It was planned that McDivitt's crew would conduct the Apollo D mission - a first manned test in earth orbit of the Lunar Module. Separate Saturn IB launches would put Apollo Block II CSM 101 / AS-207 and Lunar Module LM-2 / AS-208 into earth orbit a day later. The crew would then rendezvous and dock with the lunar module and put it through its paces.

When Schirra's Apollo 2 / AS-205 mission was cancelled in November 1966, the booster went to McDivitt's mission, and it was called AS-205/208, or AS-258."

-information from Astrnautix.com: link

Command Module 101 for Apollo-Saturn 205 mission on the workstand.

NASA ID: S68-42486

LM-2 under construction in Bethpage, Long Island, New York.

NASA ID: S68-36263

This flight was cancelled due of the Apollo 1 launch pad fire on January 27, 1967. After the fire, it was decided to launch the mission on a single Saturn V as Apollo 9. The prime crew remained the same for Apollo 9 but the backup crew flew as Apollo 10.

Information from spacefacts.de: link

Launch of AS-205 (CSM-101/SA-205) from LC-34 while AS-208 (LM-2/SA-208) waiting on LC-37B to launch the next day

Screenshot from orbit-forum.com: link