Automated transmissions prevent error

FAA expects the Controller-Pilot Data Link Communications system to make routine communications easier.

The system will automate much of the information pilots say over their radios and will reduce the chance of miscommunication.

A typical voice exchange under the current system follows:
  • Controller: 'American One Twenty Three, descend and maintain flight level two three zero, then cross three zero miles northwest of Miami at and maintain one zero thousand at two five zero knots. Miami altimeter three zero one niner.'

  • Pilot: 'American One Twenty Three will descend to flight level two three zero then cross three zero northwest of Miami at and maintain one zero thousand at two five zero knots, altimeter three zero one niner.'

The pilot reads back the message'that American Airlines Flight 123 will descend to flight level 230 then cross 30 miles northwest of Miami at 10,000 feet and maintain 10,000 feet at 250 knots, altimeter 3019. If the pilot says this incorrectly, the controller must reread the clearance, and the pilot must read it back again, Thornton said. Once the clearance is correctly acknowledged, the pilot executes the clearance and the controller updates the host computer in about six keystrokes.

On the menu

Using CPDLC, the controller would select the clearance from a menu, select the flight, American Airlines Flight 123, and press 'enter' in about six keystrokes. The host computer is updated automatically.

Aircraft avionics would alert the pilot that a new ATC message has been received. The pilot displays the message and pushes a single button to send a response to the controller. This takes about three keystrokes.

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