The family of one of the Tesla employees lost in last year’s Cessna crash at East Palo Alto has filed suit against the estate of the Cessna’s pilot.  The suit alleges that the pilot’s decision to takeoff in foggy conditions was negligent.

The air traffic controller told [the pilot]: "The runway is not visible so it’s at your own risk." Thirty seconds later, the controller repeated: "I cannot clear you for takeoff because I don’t have visibility on the runway, so the release is all yours and it’s at your own risk, sir."  [The pilot] replied: "OK," and took off anyway.

The pilot had received his "release."  (". . the release is all yours".)  That means that air traffic control had reserved airspace for him so that, once off the runway, he could safely fly in the clouds.  But the pilot had not been issued a takeoff clearance. ("I cannot clear you for takeoff.")  What was that about?

When a tower controller clears a pilot for takeoff, the controller is assuring the pilot that there is no one on the runway that the pilot needs to worry about hitting.  If the controller can’t see the departure path due to restricted visibility, he can’t clear the pilot, and so the takeoff is at the pilot’s "own risk." 

But just because the controller can’t see the runway from up in the tower cab, it doesn’t mean the pilot can’t.  And as long as the pilot can see what lies ahead, there’s really no problem. 

The helipad at Palo Alto airport is on the southwest side of the field.  The tower controller’s view of that area is blocked by obstructions.  As a result, every helicopter takeoff, regardless of the weather conditions, is at the pilot’s "own risk."  It’s up to the pilot to make sure he doesn’t hit something.  That’s standard procedure.

No one would argue that every helicopter pilot who takes off at his own risk is thereby negligent.  Hard to see why the Cessna pilot should be viewed any differently.