View Full Version : 737 Beginner technical question

Adam S
24th Oct 2018, 07:50
I will soon have a sim assessment on a 738 and I am not sure about using nav1/2.

1) Is nav 1 only displayed on the left hand side and nav 2 only displayed on the RHS?
2) If two different frequencies are selected on nav 1 and 2 and we arm VOR/LOC, what's going to happen?
3) On the EFIS control panel, when choosing both VORs 1 and 2 to on on one side, what happens?
4) How is the ADF displayed in map mode? And what happens when an ADF is displayed and we change the "course" window? Is it somehow displayed on the ND?

Thank you.

24th Oct 2018, 09:56
Hi Adam,

I will try to keep my answers as simple as possible.

1. No, both are displayed on the PFD (ILS), ND (VORs/ADF) and RMI (VORs/ADF).
- VOR/ADF 1 is a thin needle - VOR/ADF 2 a thick needle. Only VOR 1 *or* ADF 1 can be selected at any given time, and same for VOR2/ADF2)

2. VOR/LOC will capture the radial selected on "master" side. the FD you selected first / or the side of which the AP is engaged.
- (HINT!) Selecting the same freq and course (ILS or VOR) on both sides (Nav 1 + Nav 2) will make life much easier.

3. Refer to Q1. It is possible to get 2 VORs (VOR1 + VOR2) or 2 ADFs (ADF1 + ADF2 ~if installed) to show up on the ND and RMI.

4. The ADFs will display similar to the VORs (Thin needle and thick needle, that is if you have 2 ADFs installed. 1 is more common). ADF needles are BLUE, VOR needles are GREEN
- (HINT!) Remember to verify the IDENT, every time you tune a new FREQ whether is be an ILS(PFD), VOR/ADF(ND)

4a. The Course, only affects the VOR. Remember that the ADF is a direction finder so changing the course will not affect your instrumentation.
- (HINT!) For reference, you should set the bearing you want to intercept on the course selector.

Hope this help. :ok:

24th Oct 2018, 10:00
1) When selecting a VOR on NAV 1 or ADF 1 on EFIS panel, it can be displayed on right hand seat (RHS) ND, an ILS cannot; when selecting a VOR or ADF on NAV2, it can be displayed on left hand seat (LHS) ND, an ILS cannot; so both pilots can always see VOR/ADF selections made on both sides of flight deck, but only see their side selected ILS;
2) The frequency being used by the flight automation is the frequency on the active side of Autopilot (AP)/Flight Director (FD); AP in CMD A & LHS FD use selected NAV 1, NAV 2 serves then as a backup; AP in CMD B & RHS FD use selected NAV 1, NAV 2 serves then as a backup; for dual channel approaches, with NAV's must be selected to the same frequency or they cannot compare each other.
3) ND will display both VOR's, each with ident, DME and needles;
4) ADF is displayed in different colour on ND, using a different pointer type; Course is not displayed on ND

A and C
24th Oct 2018, 11:30
Another useful thing with the ADF presentation is that just like the VOR if the signal is not valid the needle won’t appear in the screen, so it is not nessesary to listen to the ADF ident throughout an ADF approach ( the engineers call this function superflag ).

Adam S
24th Oct 2018, 16:40
Thank you very much for the replys.

- Will the VOR course deviation bar appear only in "VOR" move?
- If indeed both nav 1 and 2 have an in range VOR selected and both VOR 1 and 2 switches are on on either side and "VOR" mode selected, will there be two course deviation bars showing?
- Useful tips to flying a manual raw data hold based on an NDB? What would be the most helpful ND mode to use in this case?

Thank you

24th Oct 2018, 21:44
- Useful tips to flying a manual raw data hold based on an NDB? What would be the most helpful ND mode to use in this case?
Put the ND in CTR mode. On push of the button. Now you will see an ADF card with 1 or 2 bearing needles.