DC-10Tech From United States of America, joined Jun 2001, 298 posts, RR: 3 Reply 4, posted (11 years 7 months 3 weeks 3 days 12 hours ago) and read 1926 times:
It looks like an ADF loop to me. I know the TCAS is usually above and below section 41, but I have seen some placed in the rear. Some models do stick up that far, but they are rectangular shape. I have never seen a GPS antenna that large either. I mentioned TCAS because I don't see an upper TCAS on this plane... somebody must know!