If you're flying a high powered aircraft, then you probably have a flash card with 'Emergency Descent' on it.
If you're flying a normal piston aircraft, then you likely have the muscle memory down from practicing an emergency descent.
Let's do a quick review of an emergency descent because this emergency scenario actually tends to happen more often than others.
1) Decreasing Lift
Bring the power back and, if needed, start rolling in bank ranging from 30 to 45 degrees. Remember the basics of aerodynamics! If you increase bank without increasing back pressure, you'll increase horizontal lift and decrease vertical lift. Therefore, losing altitude and beginning the descent.
2) Increasing Drag
If you have spoilers, extend them. If you're flying a constant speed propeller then you'll need to place the prop in low pitch and high rpm to make it LESS aerodynamic. You want to get the aircraft down as soon as possible without overspeeding.
As speed allows, start bringing gear and flaps down.
3) Decide Your Level Off and Advise
Now you're configured and in the descent but when will you level off? Well, it depends on why you're flying an emergency descent. If you started down because you lost pressurization, then you just need a level off low enough to safely breathe without getting hypoxia (around 10,000 feet) then go from there. If you're doing so because you've lost a critical system or have a sick passenger, the question then becomes which airport are you going to?
Consider factors when choosing an airport such as:
-runway length (most important if you're flying a larger aircraft)
-maintenance facility on the field so you can get your plane fixed
-emergency crews that can reach you quickly
Whatever you decide, let ATC know as soon as possible then start thinking ahead to getting your checklist completed and ready for approach/landing.
Lastly is don't forget during all of this that if you're flying a pressurized cabin you need to first get your oxygen mask on and during the descent ensure the passenger masks have deployed!
An emergency descent is a rather simple memory item, but a good review of the basics of each item never hurts!
Questions or comments? Feedback below!