Does the US not still operate the SOSUS systems? I would think that in that general area, we would have arrays operating that could pickup something as violent as a large aircraft impact. We would at least know if it hit the water or not. Am I making too many assumptions here? We’ve used them to pick up less dramatic events in the past...
It is my opinion that ‘skunk works’ type operations knows exactly what is happening. If it landed, they’re looking at it right now. If it sank in the ocean, they know where.