If, in some unimaginable circumstance, plan B is to fail then the airship captain is to do the following.

Tell the entire crew to jump from the dirigible(failing this then the captain is to push all those out).

The captain is then instructed to retrieve from under his seat the small metal box marked "Plan X". He is to open the box and remove the cigar and the lighter supplied by the Zippo company of the USA. He is to light the cigar before cutting a small hole in the forwardmost gas bag. He is then to throw the cigar (or the lighter) into the gas bag and run for dear life. The resulting explosion is sure to take any attacking aircraft out with the balloon. If the captain is found in one peice with the cigar then he is to return the cigar to RFC HQ so that it can be reused.