No Ken, when the lead aircraft is in a 30 bank turn I stay in formation position, the horizon is irrelevant to me as my leader is my horizon and I am in exactly the same position as I was in when the lead was straight and level. Now of course if I had done a flat turn I would lose sight of the lead.
EXACTLY!! and if you cannot see your lead, you cannot see your horizon. If in straight and level flight your lead is at your 9-10 O'clock at the same altitude and you both bank 30 degrees and both maintain altitude (meaning you cannot climb to stay on your lead's roll axis) you will not be able to see your lead unless you have an eyebrow window. Tactical airdrop formations in an airlifter are very different than formations in fighters.