# Thread: CDU and Alternate Destination

1. ## CDU and Alternate Destination

In the menu INDEX->ALTN the CDU shows the nearest alternate airports. But
the distanse the CDU is calculating is very wrong, if I understand the
function right. Its shows that the closest airport is about 138nm away, but

it is 55nm away.

What is correct?

_Best Regards
Tom Stian Bjerk

2. ## Re: CDU and Alternate Destination

> In the menu INDEX->ALTN the CDU shows the nearest alternate airports. But
> the distanse the CDU is calculating is very wrong, if I understand the
> function right. Its shows that the closest airport is about 138nm away,
> but
>
> it is 55nm away.
>
> What is correct?

Can you let me check that example? What position are you at, which airports

are listed and how do you measure the distance?

I did a quick check and it looks right to me.

3. ## Re: CDU and Alternate Destination

I am flying south of ENCN (Norway) at FL370. I measure the distance with
FSNavigator and with the VOR at the airport.. using the 0603 navdata.

Best Regards
Tom Stian Bjerk

"Enrico Schiratti" wrote in message
news:409607.81201@wb.onvix.com...
>> In the menu INDEX->ALTN the CDU shows the nearest alternate airports.

But
>> the distanse the CDU is calculating is very wrong, if I understand the
>> function right. Its shows that the closest airport is about 138nm away,
>> but
>>
>> it is 55nm away.
>>
>> What is correct?

>
> Can you let me check that example? What position are you at, which
> airports
>
> are listed and how do you measure the distance?
>
> I did a quick check and it looks right to me.
>

4. ## Re: CDU and Alternate Destination

>I am flying south of ENCN (Norway) at FL370. I measure the distance with
> FSNavigator and with the VOR at the airport.. using the 0603 navdata.

Ok, I checked.

Then it is really quite simple... how do you want the aircraft to descent
from FL370 down to the airport you are currently overflying?

There is a calculation inside that list which keeps in mind what altitude
you are at, and calculates the distance over ground it takes to get there. I

put it in a long time ago, and I won't remove it just like that unless I
find out it is completely wrong.

Ciao

Enrico

> "Enrico Schiratti" wrote in message
> news:409607.81201@wb.onvix.com...
>>> In the menu INDEX->ALTN the CDU shows the nearest alternate airports.

> But
>>> the distanse the CDU is calculating is very wrong, if I understand the
>>> function right. Its shows that the closest airport is about 138nm away,
>>> but
>>>
>>> it is 55nm away.
>>>
>>> What is correct?

>>
>> Can you let me check that example? What position are you at, which
>> airports
>>
>> are listed and how do you measure the distance?
>>
>> I did a quick check and it looks right to me.
>>

>

5. ## Re: CDU and Alternate Destination

Just to underline it... there is a time listed just next to the distance...

and that can't be the current time if you are at FL370 and 3 miles from the

airport.

Ciao

Enrico

"Enrico Schiratti" wrote in message
news:409854.81201@wb.onvix.com...
> >I am flying south of ENCN (Norway) at FL370. I measure the distance with
>> FSNavigator and with the VOR at the airport.. using the 0603 navdata.

>
> Ok, I checked.
>
> Then it is really quite simple... how do you want the aircraft to descent
> from FL370 down to the airport you are currently overflying?
>
> There is a calculation inside that list which keeps in mind what altitude
> you are at, and calculates the distance over ground it takes to get there.

> I
>
> put it in a long time ago, and I won't remove it just like that unless I
> find out it is completely wrong.
>
> Ciao
>
> Enrico
>
>
>> "Enrico Schiratti" wrote in message
>> news:409607.81201@wb.onvix.com...
>>>> In the menu INDEX->ALTN the CDU shows the nearest alternate airports.

>> But
>>>> the distanse the CDU is calculating is very wrong, if I understand the
>>>> function right. Its shows that the closest airport is about 138nm

away,
>>>> but
>>>>
>>>> it is 55nm away.
>>>>
>>>> What is correct?
>>>
>>> Can you let me check that example? What position are you at, which
>>> airports
>>>
>>> are listed and how do you measure the distance?
>>>
>>> I did a quick check and it looks right to me.
>>>

>>

>