she had done two practice runs , one slowly in twinkle and the other in her own aircraft arabella , but now it was for real , and as she skimmed over schools ( with all the children outside in the play-ground , waving at her ) , houses and farms ( with their owners waving at her ) and under the high voltage cable that spanned a motorway , the top of her fin a metre below the bright orange balls that made the lines visible to vfr aircraft ( light aircraft navigating by the aa book of the road ) .