Nav Aid input on a 747-400 CDU

[DownloadDog]

How do you tune specific nav aids on a 747-400 CDU?

In particular, I'm interested in knowing the key presses required. Furthermore, does it auto-identify the beacon/ILS?

Thanks in advance.

DD

[spannersatcx]

ADF
(1) The CDU tunes the ADF receiver directly or through the FMC. The CDU provides mode and frequency selections for the ADF receiver. Frequency and mode data are entered on the left or right CDU. The CDU sends frequency and mode data on an ARINC 429 digital data bus to both FMCs. The master FMC sends tuning to the left and right ADF receivers. The master FMC is determined by the position of the FMC master switch.
(2) The operation of CDU on ADF system is as follows:

(a) Pushing the NAV RAD key on the left or right CDU causes the NAV RADIO page to be displayed on the associated CDU display CRT when FMC is the tuning source. (The ALTN NAV RADIO page will be displayed when both FMCs fail). The frequency and mode of operation for the ADF receivers can be selected on this page.

This information is sent to both FMCs. The master FMC then sends the tuning information to both ADF receivers.
(b) To tune the left ADF receiver, enter a valid ADF frequency by pressing the appropriate numeric keys on the CDU keyboard. Valid ADF frequencies consist of a three or four digit number optionally followed by a decimal point and a tenth digit and must be in the ADF frequency range. This frequency will appear in the CDU scratchpad.
(c) To transfer this frequency to the line below ADF L, press the line select key 3L. The left ADF receiver is now tuned to this frequency and operating in the ADF mode.
(d) If the ANT mode is desired, enter the letter A after the frequency. If the BFO mode is desired, enter the letter B after the frequency. If only the frequency is entered without specifying which mode is desired, the ADF receiver will default to the ADF mode.
(e) To tune the right ADF receiver, use the same procedures described above except line select key 3R is used.

VOR
(1) The VOR receivers can be tuned automatically or manually. The VOR receivers are normally tuned automatically by the FMC if a flight plan has been previously entered.

The following paragraphs describe the manual tuning procedure.
(2) The CDU keyboard is used to input tuning data. The tuning procedure depends on whether or not the FMCs are operational.
(3) If at least one FMC is operational, both receivers can be tuned by selecting the desired frequency on either the left or right CDU keyboard as follows:

(a) Press the NAV RAD key on the CDU to show the NAV RADIO page.
(b) Enter the desired frequency into the CDU scratch pad using the alphanumeric keypad.
(c) Press the line select key next to the VOR L display. The new frequency value is moved from the scratch pad on the CDU screen to the current VOR L frequency line.
(d) Enter the desired frequency into the CDU scratch pad using the alphanumeric keypad.
(e) Press the line select key next to the VOR R display. The new frequency value is moved from scratch pad on the CDU screen to the current VOR R frequency line.

(4) If neither FMC is operational, only one receiver can be tuned at a time using its onside CDU as follows:

(a) Press the NAV RAD key on the left CDU to show the ALTN NAV RADIO page.
(b) Enter the desired frequency into the CDU scratch pad using the alphanumeric keypad.
(c) Press the line select key next to the VOR frequency display. The new frequency value is moved from the scratch pad on the CDU screen to the current VOR frequency line. The selected frequency input is sent directly to the left receiver.
(d) The right receiver is tuned in a similar manner using the right CDU.

DME

The DME interrogator has two types of tuning control modes - AUTOTUNE and MANUAL TUNE. When autotuning, both interrogators are controlled by the on line flight management computer (FMC). Manual tune of the left and right interrogators are performed exclusively by the left and right CDUs respectively whenever both FMCs are disabled.

(1) AUTOTUNE Mode - Control of the DME interrogator is provided by either the left or right FMC, depending of the position of the EICAS select panel - FMC switch
Based on information in the FMC data base or from information entered in on the CDU, the DME interrogator is sent an encoded 32-bit data control word via an ARINC 429 data bus. This control word directs the DME system as required by the FMC. The NAV RADIO page display on any CDU displays current DME system configuration tuning data and allows manual entries by the flight deck to change the existing DME tuning or control configuration.
(2) MANUAL TUNE Mode - The DME interrogator is controlled in the manual tune mode whenever the system does not have a valid input from the FMC. Control of the interrogator is then provided by the onside CDU. The left and right interrogators are therefore controlled exclusively by the left and right CDUs respectively. Each interrogator has a direct input from its respective CDU. The CDU can only tune the interrogator to only one station at a time. To tune the interrogator, the CDU must have the ALTN RADIO NAV display showing.

[DownloadDog]

Thanks for that, can you also enter the 3 letter identifier for a beacon/ILS and the FMS will tune the appropriate navaid?

[banana head]

Yes you can.

[Dan Winterland]

Here's something the books don't tell you. Most pilots know that you suffix an NDB frequency with a 'B' for BFO, but you can also suffix it with an 'A' for antenna only. This gives you clearer audio reception and is great for listening to Radio 5 live for the sports results!