Do you talk that way at the dinner table? "At this time, salt is not available for guest consumption. We will inform you when it has been released for your dining pleasure."
Sounds really weird, doesn't it?
And yet that is how pretty much every airline announcement is worded. "At this time passengers are advised to ensure seat-belts are fastened securely around your persons."
The funny thing is, I suspect most flight attendants don't even know they're shifting into Airlinese - it's so natural to them.
Like that, most of us make shifts we aren't even aware of when we speak in front of groups or sit to write. It usually isn't as obvious, but sometimes it is. Different activities and circumstances elicit different mindsets - and languaging along with it. That's normal - but keep your naturalness in the process.