You don't need a cops nose to know that in a pursuit you are going to have to terminate for safety unless the helicopter gets here quickly
Jay, suggest you read the ACPO pursuit manual, pursuits should be terminated for safety reasons
immediately, it makes no mention of how close an aircraft is, if it's unsafe its unsafe.
As a Police Officer who has been involved in many pursuits, when it gets unsafe I have the brains to quit. I value my life and my livelihood, it's crass stupidity to suggest otherwise.
Pursuits still go on when aircraft are unavailable for weather, engineering etc. We are a nice to have when it comes to pursuits, they don't get terminated whether an aircraft is overhead or not. I have been on pursuits where ground units where withdrawn and in the end so was the aircraft as it was affecting the manner of driving.
Pursuits are like aviation, in the end it all comes down to safety, when the pucker factor gets high its time to leave.