Professor Chesterfield was truly a gentleman, but there was no need for him to sacrifice himself. (Quite apart from anything else, he would never hear the end of it from Raphael if he let that happen.)
He was going to crash the helicopter, then he would come to their rescue. Lucifer’s pet had to be stopped before it destroyed the whole country; he could always deal with confused police officers and frightened crowds later.
(The one thing he couldn’t fix was Roy Steel; not yet, at any rate. He knew he would have to let him go eventually, though he could easily keep a weather eye on him from afar. That was the entire reason why he was there after all.)