About 57 nm — roughly 29 minutes in a midsize jet. 3 legs live on this route right now.
Every price on EmpTleg buys the entire aircraft, not a seat.
Nothing on this route today? Widen out: every empty leg across San Diego.
Nobody schedules an empty leg. One shows up here because an operator has an aircraft finishing a trip near Palm Springs and needs it near San Diego — or needs it home, and this direction happens to be the way home. That is why the flight can be a fraction of a full charter, why it can vanish within hours, and why the return direction is a different flight entirely with its own price and its own aircraft. Watching the route beats searching it once.