TyroPichard said "How do you know this? Have you found the DFDR?"
No, the fact the aircraft entered the ocean in basically a wings level state at a high rate of descent and lowish forward speed is from the BEA interime report. I assume, perhaps incorrectly the aircraft was probably in a stalled state at that time.
What I'm really trying to understand and this is perhaps backed up by the lack of life-jackets on passengers - so I presume no message back to cabin to prepare for crash landind in sea, is whether the crew had accurate or any altitude information.
i.e. Perhaps it wasn't just the pitots that iced up, but so did the statics but there just happened to be no acars which pointed to it.