APU’s are used on the ground (usually) and can provide electrical and hydraulic power for maintenance as well as bleed air to start the engines. You “throw out the RAT” (old F-105 reference) when your’ engine is spinning the wrong way.

Isn’t the harbormaster responsible for maneuvering the ship in tight quarters and not the captain?

Lakenheath

I believe that’s a TER, not a MER. And not all planes can carry a Multiple Ejector Rack, the A-10 was limited to the Triple Ejector Rack when I worked on them years ago.

Operation Praying Mantis II