Have you ever heard an automatic terminal information service (ATIS)at a busy airport that was spoken by a robotic voice instead of a controller? If Mr. Roboto is telling you the weather, it means that the ATIS is generated digitally, known as D-ATIS. This won’t mean much to you in the cockpit unless you’re operating an aircraft with an Aircraft Communications Addressing and Reporting System (ACARS).
ACARS, developed in the late 1970s, uses VHF radio frequencies to transfer data between ground stations and aircraft. Acting like an old modem to connect to the Internet, ACARS interfaces with ground station terminals in much the same way. Networked across the United States and elsewhere in the world, messages to and from aircraft are routed to various airlines and flight departments via computer.
This service provides lots of automated features as well as communication enhancement. Most airlines that use ACARS have automated OOOI reporting, or Out, Off, On, In (Out of the gate, Off the ground, On the ground, In the gate).
These values are used for calculating en route delays and updating arrival times, as well as to pay flight crew. On most aircraft, the “out” time is generated when the main cabin door closes and the parking brake is released. When the aircraft takes off, a weight-on-wheels switch sends a signal to the ACARS and the “off” time is sent. Reverse the process for an “on” time and an “in” time. Most flight crews are paid from “out” to “in.”
Other aircraft also have the ability to automatically send maintenance messages when systems on the aircraft experience failures or faults. This can help reduce aircraft downtime and increase dispatch reliability and airline profitability; it also promotes better on-time performance (a.k.a. customer satisfaction).
In addition to automated reporting, ACARS allows flight crews to receive the ATIS information from airports with digital ATIS broadcasts as well as IFR clearances (indicated on charts as PDC—predeparture clearance).
While en route, flight crews can receive updated weather reports from destination and alternate airports, providing enhanced awareness regarding changing weather conditions along the route of flight. Should a route change be required for weather or other reasons, the flight dispatcher can send the new flight path data directly to the pilots. If there’s a change in the winds aloft along the route of flight, the dispatcher can update your fuel requirements and send you the new fuel burn numbers.
Some airlines even provide flight crews with their entire dispatch release via the ACARS. The dispatch release is a required document for scheduled air carrier service that contains details pertinent to the route of flight.
Add up all the utility and communications enhancements and it’s easy to see why nearly every major airline and flight department utilizes this technology.
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