If no descent reference waypoint with crossing
altitude is programmed, the system will use the arrival
airport and elevation, ARP reference point, not a
runway, to fix top of descent as long as an AFIS flight
plan is not used.
One minute prior to arriving at #TOD, the system
issues the VNAV WPT ALERT message and the
discrete waypoint light will flash for 10 seconds, then
(d) Pre-Selected Altitude Intercept Point
(#PRESL). When the system has an input from an
altitude pre-selector and the aircraft is flying toward
this altitude, a profile waypoint (#PRESL) appears on
the VNAV page. #PRESL, however, never becomes
the vertical TO waypoint. When the pre-selector input
is valid, ETE and RANGE to #PRESL can be found on
the VNAV Data page.
Descent reference waypoints have a fixed altitude
crossing. To create a descent reference waypoint, the
pilot can program a flight path angle or a cross at
If a programmed FPA violates a prior vertical
constraint, the system reassigns the descent reference
waypoint, using the default FPA from the VNAV Data
v. Remote Tuning.
(1) Tuning Communications Radios. This
procedure enables the pilot to keyboard tune the
aircraft radios via the CDU.
1. TUNE key Press. The Comm Radio
Tune page will be displayed.
2. Line select key Press (if necessary)
to position cursor over appropriate
3. Frequency Insert.
Trailing zeroes are not required.
4. ENTER key Press. TRANSFER?
will automatically appear.
5. ENTER key Press. The entered
ACTIVE and displays for a few
seconds before it goes to dashes.
The new frequency also displays as
appropriate comm control unit.
(MAN) adjacent to active comm frequency
indicates that the frequency has been
entered using the comm control unit. No
prompts are displayed when active comm
frequency has been keyboard entered.
The PRESET frequency displayed on the
PRESET frequency displayed on the CDU.
Each may be entered independently.
Depending on the system configuration,
the cursor can appear over the PRESET
field for either COMM 1 or COMM 2.
(2) Tuning NAV Radios By Keyboard Method
If Station Identifier Is Used.
1. TUNE key Press until Navigation
Tune page is displayed.
2. Line select key Press to position
cursor opposite the desired radio
(NAV 1 or NAV 2).
3. Station identifier Insert or verify
4. ENTER key Press. The new
frequency is displayed immediately
adjacent to the frequency field. If the
identifier is not found immediately, the
IDENT field will go to dashes until the
station is located in the database.
Once located, the identifier will be
displayed and the (KEY) annunciation
will shift to the identifier line.
When the CDU keyboard is used to tune a
navaid, the database will pair the frequency
and identifier to the nearest usable navaid.
Therefore, the identifier entered may not be
the same as the identifier that is displayed.
If the navaid is out of range, or a frequency
conflict exists, dashes will be displayed in
the IDENT field and the new frequency will
5. Frequency Verify that the ACTIVE
frequency on the control head and
CDU displays agree.