Why must lifevests be inflated just before exiting the aircraft during an emergency landing on water?

There are several reasons why lifevests are to be inflated just before exiting the aircraft:

• Inflating life vests within the cabin will create hindrances and slow down the evacuation of passengers during an emergency.

• Passengers may not be able to manoeuvre through smaller emergency overwing exits with their inflated life vests. Also, the life vests may also become damaged in the process and will not be able to serve their purpose in water.

• Inflated life vests are also very stiff and will keep passengers' necks in an upright position, impeding their ability to brace on impact.

• If a cabin becomes engulfed with rising water during an emergency landing on water, passengers may become trapped inside a cabin as an inflated lifevest will prevent a passenger from being able to dive underwater to reach exits.