Step 1: Step One: Take the Seat and Level Off
Examine the artificial horizon (Shown in the image below - it's the blue above the brown, with a little pair of wings in the middle). The blue up top represents the sky, and the brown below represents the ground. Gently take the yoke (The stick controlling the aircraft), and pull up or down accordingly to make the little wings in the middle, between the blue and the brown.
If it seems that this is not working, look outside, and visually level off.
Levelling off means that you will fly straight, and not hit the ground or stall and start dropping fast.
Step 2: Step 2: I've Made the Little Wings Go in the Middle, But the Plane's Falling Like a Rock.
If you've levelled out the plane, but you're falling fast, and you're hearing this strange insistant buzzing or wailing sound, you've stalled. This is very, very bad. It means that the plane is no longer flying, but falling.
The thing to do is pitch down and go into a nosedive. As you near the ground, slowly pull up, so you don't crash. If you continue to fall, then buckle your seat belt, 'cause it's gonna get bumpy. Level out as you approach the ground, and try to belly land (Land without the gear down).
Step 3: Step 3: Okay, It's Level. Now What?
There is something called a radio stack in every aircraft, which allows radio communication. Grab the microphone, and look for a button labelled "PTT", which stands for "Push To Talk". Grab the pilot's headset as well, and put it on. Push the button, and yell "Mayday! Mayday!" into it. Then, still holding down the button, describe your situation (E.g. "I'm on a 747 bound for Germany, and the pilot's just died!"). Release the button, and wait for a reply. After 10 seconds, try again. If there is still no responce, change the frequency to 121.5 as you would with a normal radio. Then repeat what you did before. 121.5 is the emergency frequency.
If you get a reply, explain your situation again, and you will recieve help. Follow instructions exactly.
If you can't set the frequency, and/or you still hear no reply, look at the bottom screen on the stack. This is the transponder. Set it to 7700. This will alert ATC (Air Traffic Control) to your emergency.
Step 4: Step 4: Okay, I've Done What They Said, Now What?
The first thing to do is line the plane up with the runway. Make sure you are headed right for it, and flying parallel, so you won't start veering off. Point the nose slightly down, and start to decend. Make sure the wheels are down! ATC should explain which lever does this, as it varies from aircraft to aircraft.
From Phil B:
"There is also the matter of slowing the plane for landing speed, but not so much that it stalls. Slowing is a combination of pointing the nose up slightly while manipulating the throttles to keep speed up, but also not too much extra throttle to keep the plane from climbing. Adjust the throttle so the plane descends about 500 feet per minute. Add a notch or two of flaps so the plane has enough lift at lower speeds without stalling and dropping as if it were a rock."
"Lining up with the runway can be deceiving. It is easy to aim for the end of the runway and not notice the plane is not really lined up. It is a lot like looking down the length of a board to see if it is straight or warped. Looking at the whole length of the runway at the same time helps to know if the plane is too far right or left of the runway so there are no surprises at the last few seconds. Aim for the large numbers painted at the end of the runway."
As you approach the runway, gently pull up, so the main wheels touch down first. When you hit the ground, slowly put the nose back down, and apply the brakes (Which usually come one automatically - if not, ask ATC which button to press or lever to pull).
More from Phil:
"Pulling up just before the wheels touch down is a fingertip sensitive operation. If you pull up too much the plane shoots back up into the air. You pull up just enough to hold the plane off of the runway while it settles down gently onto the runway. (When planes bounce back up into the air a few feet on landing, it means the airspeed was too great, yet.) All of this also is based on the infrequent circumstance that there might be no crosswind that will cause the plane to drift off to one side of the runway during the approach. In the event of any crosswind you need to know to use a combination of dipping a wing slightly into the wind to make the plane pull toward the wind while also adding a little rudder in the opposite direction to keep the plane from going too far toward the wind and keeping it headed toward the runway."
Keep the plane going straight, and slowly come to a stop.