# Use Alt Calc

Alt Calc estimates alternate availability using the fuel at the hold fix, alternate fuel requirements, final reserve, extra fuel, and hold burn.

<figure><img src="/files/cSkcrPPiudRtrGAtmfsh" alt=""><figcaption></figcaption></figure>

## <mark style="color:$warning;">Load from OFP</mark>

If you already loaded an OFP:

1. Open the OFP alternates section.
2. Send alternates to Alt Calc.
3. Open **ALT CALC**.
4. Review the imported aircraft, alternates, fuel figures, and hold fix time.

<figure><img src="/files/2EL7recA0w6Z1cEWNUIh" alt=""><figcaption></figcaption></figure>

## <mark style="color:$warning;">Enter manually</mark>

You can also use Alt Calc without an OFP.

1. Select or create an aircraft type.
2. Enter fuel at the hold fix.
3. Enter extra or delay fuel if applicable.
4. Enter final reserve fuel.
5. Enter a hold fix UTC time if you want live countdowns.
6. Add alternates with their OFP fuel requirement.

<figure><img src="/files/ZTLcEDfLJei3zLJgINr3" alt=""><figcaption></figcaption></figure>

## <mark style="color:$warning;">Read statuses</mark>

| Status                                        | Meaning                                                             |
| --------------------------------------------- | ------------------------------------------------------------------- |
| <mark style="color:$success;">Ample</mark>    | Sufficient holding fuel remains after divert.                       |
| <mark style="color:$warning;">Marginal</mark> | Holding margin is reducing and should be monitored.                 |
| <mark style="color:$danger;">Critical</mark>  | The alternate is near its limit.                                    |
| <mark style="color:$danger;">Lost</mark>      | The alternate is no longer available using the entered assumptions. |

## <mark style="color:$warning;">Last exit time</mark>

For each alternate, Alt Calc can show the latest time to leave the hold and still preserve the required fuel. Treat this as an advisory calculation based on the entered data and assumptions.

## <mark style="color:$warning;">Declare divert</mark>

The divert modal helps log the selected alternate and event time in the alarm/event log. Use company and ATC procedures as the controlling source.


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