You don't know what you're talking about. The above are not opinions or assertions. They are widely known facts. Your refusal to accept them says more about you than it does about the real world.
Have a good sleep.
-Gumboot
Good morning.
Yeah that's right Gum just like no one mistaked any of the flights for military aircraft. That's what you claimed last time you said I didn't know what I was talking about. To say they knew for sure what objects they were tracking is an opinion and a wrong one.
http://en.wikipedia.org/wiki/Transponder_(aviation)
Operation
In flight a pilot is told to squawk a given code by air traffic control over the radio, such as in the phrase "Cessna 123AB, squawk 0363". The pilot inputs these digits and his blip on the radar becomes correctly associated with his identity.
Because
primary radar gives position information
but lacks altitude information, mode C and mode S transponders report altitude. Around busy airspace there is often a regulatory requirement that all aircraft be equipped with an altitude-reporting mode C or mode S transponder. In the United States, this is known as a Mode C veil. Mode S transponders are compatible with transmitting the mode C signal, hence no need for a separate designation. Without the altitude reporting, the controller cannot see any altitude information, and
the controller must rely on the altitude as reported by the pilot. This has resulted in at least one accident. On 31 August, 1986, a Piper Archer with a pilot and two passengers had inadvertently penetrated the 6,000-foot floor of controlled airspace without a clearance and collided[1] with Aeromexico Flight 498, a DC-9 with 58 passengers and 6 crew at an altitude of 6,650 feet. The Archer had only mode A reporting capability and the controller assumed it was below the controlled airspace.
Secondary Surveillance Radar is referred to as "secondary", to distinguish it from the "primary radar" that works by passively bouncing a radio signal off the skin of the aircraft. Primary radar works best with large all-metal aircraft, but not so well on small, composite aircraft. Its range is also limited by terrain and rain or snow and also detects unwanted objects such as automobiles, hills and trees. Furthermore not all primary radars can estimate the altitude of an aircraft.
Secondary radar overcomes these limitations but it depends on a transponder in the aircraft to respond to interrogations from the ground station to make the plane more visible and to report the aircraft's altitude.
