Radar handoffs- Before automation and after
Before automation, all radar handoffs were verbal over the "shout line" i.e. direct telephonic connection with adjacent air traffic facilities for rapid communications.

With automation, radar handoffs can be done silently

Later software improvements allowed a radar handoff to be initiated automatically

Manual handoffs

In order to provide positive control of Instrument Flight Rules (IFR) aircraft controllers may not allow a target to enter the airspace of another controller without their approval. This approval is accomplished through a "Radar Handoff". To give an idea of why manual radar handoffs were time consuming and distracting, below I provide a simulated scenario of a typical handoff between two ficticious radar approach control facilities Charlietown and Hotelburg,

A Controller at "Charlietown" approach control presses the hot-line button and says Hotelburg approach

"Hotelburg approach, handoff" -waits for Hotelburg to answer

Hotelburg approach is busy and doesn't take the call

Charlietown approach is busy also and impatiently says again

"Hotelburg approach, I've got a handoff for you!"

Hotelburg answers, "okay, okay, go ahead Charlietown"

Charlietown: "Handoff three south of Pulga intersection: Baron Three Five Three Seven Romeo (N3537R), seven thousand, requesting straight-in to runway 33 at your place - I've got him on a 350 heading right now to miss that guy at his eleven o'clock, he'll be direct to Charlietown Airport
on contact"

Hotelburg: "Radar contact Baron Three Five Three Seven Romeo"

Then finally the controller at Charlietown says to the pilot Baron Three Five Three Seven Romeo contact Hotelburg approach on 124.5

That is about six transmissions including the last one to the pilot.

As you can see, one manual radar handoff required a lot of coordination over the shout-line, during which time not directly listening to the radio frequency, and attention is divided between making the handoff and watching the radar display

Radar handoffs with automation

Charlietown approach using a track or slew ball, kind of like a computer mouse, but stationary and really, really heavy-duty. He/she slews out to Baron 3537R's data block and presses the button on the slew ball.

At Hotelburg approach, although busy talking to aircraft sees the "datablock" of Baron 3537R flashing, indicating a handoff. Hotelburg approach slews out to the target and clicks on it, indicating acceptance of the handoff, equivilent to saying "Radar Contact" on the manual handoff.

Now Baron 3537R's datablock flashes on Charlietown approach's display which means that the handoff has been accepted.

As in the above example the controller at Charlietown says to the pilot "November 3537R contact Hotelburg approach on 124.5

The whole series of verbal communications was eliminated

Automatic handoffs
As software was upgraded, one of the major enhancements was "Automated Handoff". With this feature the automation specialist could define a volume of airspace with a series of latitudes / longitudes, upper and lower altitudes, and based on the the route of flight. If a flight enters this volumn of airspace on the a proper heading the Air Traffic computer itself would initiate the handoff to the correct facility. That's a big deal because the controller does not have to remember to do it. It just happens. However the controller has to make sure that the that the automated handoff initiated and is accepted by the facility to which the handoff was sent. But still that is a lot less to worry about than the two previous scenarios. If the auto-handoff fails for any reason a warning is flashed to the controller.
Continue to ATC Automation part 6 The Tower Controller"
Alone in a sea of non-programmers
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