Finished up the README.

README.md

@@ -50,4 +50,100 @@ altitude and speed.
 
 Airplane Tracking
 -----------------
-
+There are three basic methods of the `airplane.ControllableAirplane` class which allow for tracking:
+
+1. `getName()` - returns a unique identifies as an ASCII string. The string
+will include letters and numbers. These are displayed in the simulator above
+and to the right of each airplane's position.
+2. `getPosition()` - returns a `vector.Threevec` containing the current
+position of the aircraft. The coordinates are in meters, with the x-axis
+pointed East, the y-axis pointing North, and the z-axis pointing up with z=0
+being sea-level.
+3. `getVelocity()` - returns a `vector.Threevec` containing the current
+velocity of the aircraft. The components are in meters per second with
+directions corresponding to those in the `getPosition()` method.  
+
+Airplane Control
+----------------
+There are several methods of the `airplane.ControllableAirplane` class which
+send control commands to the airplanes. They are as follows:
+
+1. `isControllable()` - returns True if the airplane can be controlled. This
+will be true for all airplanes in the simulation.
+2. `sendHeading(heading)` - commands that the aircraft turn to heading where
+heading is an angle in radians that runs from 0 being North, through pi/2
+being East, pi being South, and 3pi/2 being West. The aircraft will not
+immediately assume this heading, but will turn toward this heading. The
+maximum turn rate of these airplanes is 1.5 degrees per second.
+3. `sendAltitude(altitude)` - commands the aircraft to climb or descend to
+altitude` in meters. The rate of climb and descent is limited by the pitch of
+the aircraft above or below the horizon. The maximum rate and which the
+airplane can change altitude is at its speed times the sine of the pitch
+angle. The maximum pitch angle for these airplanes is 7.5 degrees. The
+aircraft is also limited to cruising between 6,000 and 10,000 meters altitude
+and will not exceed those bounds.
+4. `sendSpeed(speed)` - commands the aircraft to travel at the speed speed in
+meters per second. The aircraft is limited to speeds between 215 and 250
+meters per second and will not exceed those bounds. 
+
+Airplane Request
+----------------
+The airplane is trying to get somewhere. In order to do that it will have
+available a desired heading, altitude, and speed. These requested parameters
+are available using the following methods of `airplane.ControllableAirplane`:
+
+1. `getDesiredHeading()` - returns the desired heading in radians with 0 being North, pi/2 being East, etc. 
+2. `getDesiredAltitude()` - returns the desired altitude in meters above sealevel.
+3. `getDesiredSpeed()` - returns the desired speed in meters per second.
+
+After dodging any potential aircraft in the way, the airplane should be allowed to resume these settings, but you will have to send it the appropriate commands.
+
+Flight Control
+--------------
+
+You will be modifying the `flight_control.py` file, which contains the flight
+control system. The system is encapsulated in a class called
+`FlightController`. This class is instantiated by the simulator and then every
+10 seconds the `executeControl` command is called with a single argument that
+contains a list of all airplanes in the simulation. An example is provided in
+the source code, which I copy below.
+
+```python
+import airplane
+import vector
+import math
+
+class FlightController(object):
+    """This is the flight controller class. Its job is to send commands to
+    the airplanes to make sure they don't hit each other
+    and get where they are going."""
+    def __init__(self):
+        """If you need to initialize any data structures do it here."""
+        pass
+
+    def executeControl(self,airplane_list):
+        """Every 10 seconds a list (airplane_list) of flying objects will be
+        passed to you. You can find the positions of the airplanes and issue
+        flight control commands to them."""
+        for a in airplane_list:
+            a.sendHeading(a.getDesiredHeading())
+            a.sendAltitude(a.getDesiredAltitude())
+            a.sendSpeed(a.getDesiredSpeed())
+```
+
+Note that the example only sends airplanes their own desired headings,
+altitudes, and speeds. It does not check for or avoid collisions. You will
+need to change that by making sure that airplanes do not get too close or
+crash.
+
+During the simulation you will receive penalties for airplanes crashing or for
+airplanes being too close together. Airplanes crash if they are within 100
+meters of one another. Airplane are too close if their altitudes are within
+600 meters of another airplane while they are within 10 km of one another. You
+will receive a 1000 point penalty for any airplane that crashes and a 100
+point penalty every 10 seconds for each airplane that is too close to another.
+
+At the end of the simulation you receive 1000 points for each airplane that is
+still flying. You get a bonus of 500 points for each airplane on the right
+heading, 250 points for each airplane at the right speed, and 250 more points
+for each airplane at the right altitude at the end of the simulation.