Originally Posted by
ackattacker
I agree with this post. I hate to second guess the crew, but from the video the cabin was pretty clear by the time they landed, and nothing was on fire internally or externally. Sounds from descriptions like the smoke was likely engine oil or combustion byproducts getting into the pack and once the engine was secured the smoke stopped.
Luckily it sounds like nobody was injured during the evacuation, and it makes good press I suppose, so all's well that ends well.
As for dropping the masks... probably doesn't do much for the passengers (as noted, the masks don't seal well against your face) but with no actual fire in the cabin it doesn't hurt anything either and makes everybody feel like they're doing something instead of just sitting there coughing and waiting for the end to come.
The masks are not designed to seal to the face. They work on the same principle as nasal cannula type GA systems. They simply inject a small amount of O2 into the ambient air. They should not be deployed in a smoke situation and the O2 canisters burn very hot and can create some smoke which makes things more confused.