How- User defined fix A320 MCDU

[satpak77]

New guy in the A320. For situational awareness, Tried to build a fix at 30 miles, for a 250 speed/10,000 user created constraint due to going into rural airport with no STAR. the other day I did this via FPLN page, L1, entered destination airport into amber boxes, then 30 mile as radius.

after that a small asterisk would appear to allow me to insert into the flight plan

On a recent flight NO asterisk appeared whatsoever, and we never figured out why.

any MCDU experts have some advice? Aircraft was 2015 year model 321. Honestly don’t know if it was a Thales or Honeywell box.

be gentle. New guy trying to learn.

Thank You

[TheEdge]

Hi, Just go to FIX INFO page, insert airport name, then type 30 and choose RADIUS, immediately you will get in the ND a radius of 30 NM centered on the Airport.....did i understand well what you need ?

[FlightDetent]

Not fully.

He's trying to find why the asterisk did not show up after inserting 30 and getting the ring. Which creates a waypoint at the intersection with F-PLN trajectory.

[TheEdge]

Ok...so from FCOM:


When the circle intercepts the current flight path, the FMGS compute the time, the along path distance and the altitude at the first intersection point, from the current aircraft position (small green font).
A large blue star is then displayed to insert the intersection waypoint into the flight plan.....etc


Based on the above i can only imagine the airport inserted was not the corrrect one ? or maybe the flight plan was not completed thus not intercepting the circle ?

[satpak77]

Not fully.

He's trying to find why the asterisk did not show up after inserting 30 and getting the ring. Which creates a waypoint at the intersection with F-PLN trajectory.

correct. no asterisk, and no insert ability

[FlightDetent]

maybe the flight plan was not completed thus not intercepting the circle ? I was also thinking 2 itersection places if the airport was along the route while they were conducting the research. Even a destination where a STAR takes you in and out of 30 NM is not beyond imagination, which would be 3 intersections then.

Somehow the tone of OP suggests he would have noticed.

[KingAir1978]

Is it possible that there was a route discontinuity? Maybe the final airway point was more than 30 miles from the field, therefore the 30 NM radius didn't intersect with the flight plan?

[satpak77]

thanks guys, yeah not sure what the issue was.

[Amadis of Gaul]

Is it possible that there was a route discontinuity? Maybe the final airway point was more than 30 miles from the field, therefore the 30 NM radius didn't intersect with the flight plan?

That would be my guess as well. In fact, in my Honeywell R1A guide, it states:

"...Pushing 4L, after a radius has been entered, calculates whether a radius point exists on the flight plan from the waypoint on the FIX INFO page. IF A RADIUS POINT IS FOUND (emphasis mine), an asterisk is displayed in 4L next to the entered NM radius...

<snip>

"...If a radius point does NOT (emphasis mine) intersect the flight plan, white dashes are displayed in the UTC, DTG and ALT fields on the MCDU..."

So, it sounds like Fifi did not see where the flight plan was going to be within 30nm of the field.

[Amadis of Gaul]

Honestly don’t know if it was a Thales or Honeywell box.


May I ask why?

[satpak77]

May I ask why?

can’t remember, flew multiple tails that day. We have both boxes in the fleet

[Amadis of Gaul]

can’t remember, flew multiple tails that day. We have both boxes in the fleet

We only have Honeywell, so I don't have a Thales guide, but I suspect in this regard they're similar.

[Black Pudding]

Were you in heading or NAV

[FlightDetent]

Nice catch. The 'abeam/intersect' cannot be input if this would invalidate the active leg, i.e. replace the current TO waypoint, right?

[Server too busy]

The asterisk will not be visible if it will be over a waypoint that is on the active flight plan.

You can leave the ring there but not insert it.