David Garratt Hoag (October 11, 1925 – January 19, 2015) was an American aeronautical engineer who was Director of the Apollo Program at the Massachusetts Institute of Technology's Instrumentation Laboratory, later renamed the Charles Stark Draper Laboratory.

While in the military, he attended the Massachusetts Institute of Technology, where he received a bachelor's degree in electrical communications and later a masters in aeronautical engineering instrumentation.

[1] At MIT Instrumentation Laboratory, Hoag worked on the antiaircraft fire control systems and was Chief Technical Design Engineer and Program Manager for the Polaris Fleet Ballistic Missile Program.

They had to be created in a fail-safe way, as the astronaut crew would be in danger if one drifted, and needed to be carefully constructed to keep the gimbals from freezing and locking up.

NASA then asked the lab to also take on the work of creating a digital flight control system.