From
Where We Came...
Identify..
Friend or Foe
By Robert Ezell
October 14
The Transponder --The forerunner to today's
Air Traffic Control (ATC) Radar Beacon System was developed during Would
War II to enable military radar operators to Identify aircraft as friend
or enemy. That system was known as IFF (identification friend or foe).
Utilizing both ground and airborne equipment the system's ground
transmitter sent a Signal to the aircraft transceiver which in turn
replied in a set code depending upon how the pilot had tuned his
selector. Only a few codes were used at that time and these were changed
daily or more often.
When radar was first implemented in the Air Traffic Control System
the normal radar echo return from the metal surfaces of aircraft seemed
to be sufficient to identify an aircraft on the radar scope. But as
traffic increased, particularly in the high density terminal areas, the
need for positive means of identification was soon recognized. The old
World War II IFF, 10 code, system seemed to be the answer or at least a
beginning for the Air Traffic Control Radar Beacon System The first ATC
transponders developed for the system had a Capability of 64 different
codes There are now 4,096 individual codes and in addition by using a
transponder with mode IC attachment the system is capable of reporting
the aircraft's altitude.
Who Needs a Transpondor? Pilots normally prefer to fly VFR and
will continue to do so in most of the U.S. airspace in the foreseeable
future. They may continue to fly VFR and still enjoy the advantages of
the FAA radar service network without being under the control of ATC.
When flying within an area of radar coverage, and the aircraft can be
identified, pilots may request radar assistance or service providing
they have a two-way radio for communicating with the radar facility.
This does not place them under positive control but they can receive
radar assistance and surveillance especially when their aircraft is
transponder equipped. The transponder is simply an electronic device
that aids the controller in making faster and more positive
identification of aircraft.
Aircraft without a transponder can normally be detected by radar but
not as distinctively and may require the pilot to alter course so the
radar operator can establish positive identification. With radio
communications and a transponder, a pilot knows that the controller at
the radar facility has an immediate, electronic picture of the
aircraft's identity, speed, and direction of flight. And with the mode C
attachment the controller also knows the altitude of the aircraft which
greatly reduces the need for communication between pilot and controller.
The transponder is your best ticket for sharing the advantages of the
FAA's Air Traffic Control network especially in busy terminal control
areas.
Terminal Radar Service
There are currently three stages of terminal radar service:
Stage I - provides traffic information and limited vectoring to VFR
pilots when the controller's workload permits. Stage II - offers traffic
information and vectoring, plus sequencing of arriving VFR aircraft into
the traffic pattern and traffic advisories for departing aircraft Stage
III - provides all of stage I and II plus separation service for VFR
pilots from IFR and other participating VFR traffic within a Class B
area.
Procedures for operation within or through a Class B are:
- Plan during pre-flight preparation for
alternative routes and altitudes in the event that you are unable to
obtain your desired clearance. Refer to your Sectional Aeronautical
Chart or VFR Terminal Area Chart for Class B boundaries.
- Do not enter a Class B without specific
clearance.
- Contact the controller far enough from the Class
B boundaries to permit altering your course if traffic conditions do
not permit your immediate clearance into the Class B.
- When you contact the controller state the
following:
- Your full call sign
- Make/model of your aircraft
- Whether or not your transponder has Mode C
capability
- Your position
- Your destination
- Your route
- The altitude you are requesting
VFR flight following will give you another set of
eyes to get you to your destination. You are still responsible for
avoiding other aircraft, clouds, and obstacles--so keep scanning. Most
controllers will often remind the pilot using flight following to remain
VFR. Never get complacent while flying. You’re still Pilot In Command
and you’re responsible for everything that goes on while the plane is
airborne. Look out the window.
|