ALTERNATE AIRPORTS

Alternate Airports Lesson by wifiCFI


Alternate Airports

What is an Alternate Airport?

An alternate airport is an airport included in a flight plan other than the destination airport.

This airport is filed and used if conditions (weather, emergencies, etc.) do not permit a landing at the desired destination airport.

When is an Alternate Airport Required for an IFR Flight?

Weather Conditions at the Destination Airport: FAR 91.169(b)(2)(i)

1, 2, 3 Rule:

Between 1 hour Before to 1 hour After the Estimated Time of Arrival:

Ceilings < 2,000’ and/or

Visibility < 3 SM (Statute Miles)

If the weather is reporting less than these values at the destination airport, an alternate airport must be filed on the IFR flight plan.

Approaches at the Destination Airport: FAR 91.169(b)(1)

If the destination airport does not have an approved IAP (Instrument Approach Procedure)

Note:

It is considered wise to file an Alternate Airport on all IFR Flight Plans.

However, it is only mandatory under the 2 conditions listed above.

1, 2, 3 Rule Examples:

Scenario 1: ETA is the 13th at 1830Z Time, weather is as follows:

KOGD 131740Z 1318/1418 20010KT P6SM SCT120   FM131900 27007KT P6SM SCT120   FM140300 16006KT P6SM SCT120

Is an Alternate Airport Required for this flight to Ogden, UT?

No.

Explanation

For 1 hour before to 1 hour after our ETA of 1830Z, the forecasted visibility is greater than 3 SM and the forecasted ceilings are greater than 2,000’.

Scenario 2: ETA is the 13th at 1830Z Time, weather is as follows:

KOGD 131740Z 1318/1418 20010KT P6SM SCT120  FM131900 27007KT 2SM BKN010  FM140300 16006KT P6SM SCT120

Is an Alternate Airport Required for this flight to Ogden, UT?

Yes.

Explanation

For 1 hour before to 1 hour after our ETA of 1830Z, the forecasted visibility is less than 3 SM and the forecasted ceilings are less than 2,000’.

Scenario 3: ETA is the 13th at 1830Z Time, weather is as follows:

KOGD 131740Z 1318/1418 20010KT P6SM SCT120  FM131900 27007KT 4SM BKN010  FM140300 16006KT P6SM SCT120

Is an Alternate Airport Required for this flight to Ogden, UT?

Yes.

Explanation

For 1 hour before to 1 hour after our ETA of 1830Z, the forecasted visibility is greater than 3 SM but the forecasted ceilings are less than 2,000’.

How to File an Alternate Airport

Prior to selecting an alternate airport, we must verify that the desired airport complies with the rules listed in FAR 91.169(c)(1)(i)(a-b)

Standard Alternate Minimums:

Airports with an approved Precision Approach Procedure:

Minimum of 600’ Ceilings and 2 SM Visibility at the ETA

Airports without an approved Precision Approach BUT with an approved Non-Precision Approach Procedure:

Minimum of 800’ Ceilings and 2 SM Visibility at the ETA

Airports with no approved IAP (Instrument Approach Procedure):

Ceiling and Visibility to allow a descent from the MEA down to the Alternate Airport (and landing) under VFR Conditions at the ETA

If the weather does not meet the above minima, the pilot must select a different Alternate Airport.

Non-Standard Alternate Airport Minimums

The previous slide showed Standard Alternate Airport Weather Minimums.

However, not all airports and approaches have Standard Minimums.

Some have Non-Standard Minimums.

You can tell if an approach procedure has Non-Standard Minimums by looking at the Approach Plate.

You can find the Non-Standard Alternate Minimums for the specific approach in the “Instrument Approach Procedures Chart” under the Airport Name and Approach name you desire to use.

No Alternate Airport Fuel Requirements: FAR 91.167

If there is no Alternate Airport on an IFR Flight Plan, the pilot must plan enough fuel to:

Fly to the: 

Destination Airport then -  

Additional 45 min Fuel Reserve.

If it becomes necessary to file an Alternate Airport on an IFR Flight Plan, the pilot must plan enough fuel to:

Fly to the: 

Destination Airport then to - 

Alternate Airport then have - 

Additional 45 min Fuel Reserve.

FAA Sources Used for This Lesson

Federal Aviation Regulations Part 91


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