DADE Aircraft Communication Systems 3 — Questions and Answers
Question 1: During oceanic operations, when does a dispatcher typically use CPDLC (Controller-Pilot Data Link Communications)?
- Only when HF radio is unavailable due to solar flares
- To send and receive ATC clearances and position reports digitally, reducing voice congestion (Correct answer)
- Exclusively for weather deviation requests within domestic airspace
- As a backup to TCAS resolution advisories
Correct answer: To send and receive ATC clearances and position reports digitally, reducing voice congestion
CPDLC allows ATC and pilots to exchange messages digitally, reducing frequency congestion and improving accuracy in oceanic and remote airspace.
Question 2: What is the standard VHF communications frequency band used for air-to-ground aeronautical communications?
- 108.0–117.95 MHz (navigation band)
- 118.0–136.975 MHz (Correct answer)
- 137.0–144.0 MHz (satellite uplink)
- 156.0–174.0 MHz (marine VHF)
Correct answer: 118.0–136.975 MHz
Aeronautical voice communications use VHF frequencies between 118.0 and 136.975 MHz, with 25 kHz or 8.33 kHz channel spacing.
Question 3: Which of the following best describes the HF communication challenges dispatchers should anticipate on North Atlantic tracks?
- HF provides highly reliable, static-free communications at all times
- HF communications may be degraded by ionospheric disturbances, especially during solar events (Correct answer)
- HF is only usable during daylight hours due to ionospheric absorption
- HF has a maximum range of 500 nm regardless of frequency selected
Correct answer: HF communications may be degraded by ionospheric disturbances, especially during solar events
HF propagation is subject to ionospheric conditions, and solar activity can cause blackouts or significant signal degradation.
Question 4: An aircraft transmits an ACARS OUT message. What event does this typically report?
- Aircraft has landed at the destination airport
- Aircraft doors have closed and the aircraft has pushed back from the gate (Correct answer)
- Aircraft has reached its cruising altitude
- Aircraft fuel load has been verified by the captain
Correct answer: Aircraft doors have closed and the aircraft has pushed back from the gate
ACARS OUT (O) message is generated when the aircraft leaves the gate/pushes back, with doors closed and brakes released.
Question 5: What is the purpose of the 8.33 kHz channel spacing now required in European airspace?
- To provide better voice quality on crowded HF bands
- To triple the number of available VHF communication channels in congested airspace (Correct answer)
- To allow ACARS datalink to operate on VHF voice frequencies simultaneously
- To enable TCAS to use voice warnings on discrete frequencies
Correct answer: To triple the number of available VHF communication channels in congested airspace
8.33 kHz channel spacing replaces 25 kHz spacing, tripling available VHF frequencies to reduce congestion in high-density European airspace.
Question 6: Under Part 121, how frequently must a dispatcher attempt to contact a flight that has not checked in as required?
- Every 30 minutes until contact is established
- As soon as practical and at intervals specified in the ops specs (Correct answer)
- Every 2 hours during oceanic flight only
- Only once per duty period unless an emergency is declared
Correct answer: As soon as practical and at intervals specified in the ops specs
FAR 121.99 and operator ops specs define specific contact requirements; the dispatcher must make contact attempts as specified and document efforts.
Question 7: What does an ACARS 'IN' message signify?
- The aircraft has entered Class B airspace
- The aircraft has arrived at the gate with parking brake set (Correct answer)
- The aircraft has intercepted the ILS localizer inbound
- The aircraft has entered international airspace
Correct answer: The aircraft has arrived at the gate with parking brake set
The ACARS IN (I) message in the OOOI sequence is triggered when the aircraft arrives at the gate and sets the parking brake.
DADE Aircraft Communication Systems 3
During oceanic operations, when does a dispatcher typically use CPDLC (Controller-Pilot Data Link Communications)?