I am a regional FO, and was hand flying a visual approach to RWY 35 in KPHL earlier today. As we approached the Delaware River, a large oil tanker began to transit the final approach path on its way to sea. The ships can be large, with antennas to boot. We were watching it carefully and I mentioned that it looked as though it would pass directly underneath us as we flew directly over it. Height over the river on this approach is about 300’.

The captain said to be ready for the tower to call a go around if it was an issue, and remarked that if it wasn’t, they wouldn’t call one. Basically, that we were not the ones to determine if a ship posed an issue on short final and that ATC monitors that obstacle clearance.

I don’t have enough experience to know if that’s true, but we continued the approach and landed safely. As we passed over the ship, the bridge was directly beneath us and I swear I could have counted the crossbars on the antenna. It would surprise me if we had more than about 100’ of clearance between the top of the antenna and our main gear.

We were so close in fact that I became distracted from the PAPI and flew slightly high and off centerline. I had to correct to avoid a go around for being unstable at 200’.

All said, whether was the CA said is true or not I believe I was wrong not to assert my discomfort and go around prior to passing over the ship. That’s a lesson learned. But I ask my fellow aviators of Reddit, particularly those with a lot of Philly flying: is he right? Does ATC actually monitor and/or meter river traffic to ensure no transiting ships cause collision hazards to aircraft? And, if anyone knows, what are the FARs regarding watercraft clearance while on short final? Obviously obstacle clearance is different during the approach phase from the typical 1,000’ or 2,000’ in mountainous terrain, but I haven’t ever heard how it relates to ships and shipping lanes