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IFR alternates in the real world

This subject came up over a cup of coffee the other day.

A student and an instructor where deep in the minutia of whether or not the TAF would allow a certain airport to be used as an alternate. I was asked for my opinion.

I said the legal alternate is the least important of the 4 alternates that should be part of every flight plan.

They are

  • The prefered alternate: This is the one you actually want to go to if you miss at your destination because it is the most convenient/cheapest/closest etc etc. It doesn't need to have alternate mins, just approach mins and is the airport you are going to ask to go to if you miss.

  • The gold plated alternate: This is for those really crap weather days and is the place you will go to if there is a significant and unforcasted degradation in the weather

  • The legal alternate: This is what you put on your flight plan

  • The enroute alternate: This is where you are going to go if the bad thing happens enroute and should be updated as the flight progresses.

Before looking for alternates you should first look at the overall weather picture. If there is a widespread area of cap weather then just because you can find one airport that is just above legal alternate mins doesn't mean you are automatically good to to go. Widespread morning fog/low stratus is a good example of a gotcha situation. I once had a case where the flight was to a destination 27 miles away but the nearest sold gold alternate was 375 miles away and so that was what the flight was fueled for.

Wine, Women, and Airplanes = Happy
Canada

Agreed.

Alternates should always be chosen for your and your passengers' convenience

Same with fuel stops: pick places which are worth spending a night in.

Enroute alternates is an interesting one. The concept tends to imply that you can get destination weather easily while enroute. Sometimes you can, sometimes not. I like that method for long flights because I can get the wx for various airports using a satphone internet connection. A GPS-linked fuel totaliser might be another factor in an early decision to go to an alternate.

Why is the filed alternate a "legal" alternate? You can nominate any airport as your alternate, enroute, and divert there. In Europe, filing an alternate merely means they will be CCd on the flight plan. They will ignore it until you actually turn up (very few airports take any action on receipt of a flight plan for potentially inbound traffic) and if you didn't comply with PPR/PNR requirements they might refuse a landing (rare but does happen) so then you have to declare a Mayday.

Administrator
Shoreham EGKA, United Kingdom

In Canada there is a regulatory requirement that every IFR flight plan have an alternate airport listed and that the listed airport meet legal weather limits for alternate airports. I assumed that was the case for EU airspace but I admit to very little knowledge of how things work in Europe especially with the EASA slow motion train wreck unfolding.

Enroute alternates considerations is more then just weather. Type of approach and terrain are also factors. Again in Canada airports can be few and far between with many having only non precision approaches and a lot of mountains in the West. While Europe has a much denser airport footprint it would IMO still be a good idea, say in the event of a partial engine failure, to at any given part of the flight have an idea of which direction you would want to point the airplane. At the very least it gives you something to do when watching the autopilot drive the little white airplane along the magenta line gets boring

Wine, Women, and Airplanes = Happy
Canada

I do not understand your reasons for listing, in your original post, the "legal" alternate and, separately, your "preferred" alternate. Since your "preferred" alternate must also be a "legally" acceptable one, I fail to understand while not to put your "preferred" alternate on each flight plan that requires an alternate to be nominated (?!)

YSCB

The preferred alternate only has to have weather above approach mins. The legal alternate has to have weather above the higher alternate mins. The two are often the same but when there is widespread bad weather they can be geographically far apart.

The bottom line is you need to know where you are going to go before you miss the approach because once you miss you can basically go anywhere you can get ATC to give you a clearance to. In training you are expected to mindlessly say you are going to your flight planned legal alternate, in the real world you have lots of choices and many factors could influence your choice, none of which are typically discussed in IF "this is what you must do to pass the ride" training.

Wine, Women, and Airplanes = Happy
Canada

Hypothetical scenario:

You just failed to become "visual" on your second ILS attempt at your Destination.

Your "legal" alternate (listed in your flight plan, where the weather has been forecast to be above the required, legal minima for the alternate) is 60-minutes away to the West.

Your "preferred" alternate is 60-minutes away to the East. The weather there has been forecast to be above this airport's ILS approach minima, but below the minima required of the alternate.

You are unable to get actual weather reports from either airport. All you have are forecasts, still valid, that you used while preparing your plan (and choosing your "preferred" alternate destination, I assume).

You have two hours of fuel left.

Where would you go now?

YSCB

I guess you would go to the airport which is more convenient.

I assumed that was the case for EU airspace but I admit to very little knowledge of how things work in Europe especially with the EASA slow motion train wreck unfolding.

Yes there is a requirement in IFR to plan and file an alternate which meets some criteria. But once you have done that, you don't have to divert to that airport. You can change your mind enroute.

So, as I read it, the moment you get airborne, the filed alternate does not rank any higher than any other.

On a related topic, I vaguely recall reading some discussions on US forums years ago, where this method was used to sidestep the FAA requirement that if your destination has only a GPS/RNAV approach then the alternate must offer a different type of approach (speaking from memory). Once you get airborne, it was argued, that all changes, and that is how US pilots are able to depart with only GPS and VOR kit for navigation.

Administrator
Shoreham EGKA, United Kingdom

In my opinion, the alternate is -- just like almost everything else on the flight plan -- just for the loss of communication (7600) case. Especially in Europe, you rarely (never?) fly the routing that Eurocontrol gives you and you can change just about everything once you are airborne.

You are unable to get actual weather reports from either airport. All you have are forecasts, still valid, that you used while preparing your plan (and choosing your "preferred" alternate destination, I assume).

That is a pretty unrealistic scenario in Europe or North America. Having to make such a decision (fly to unknown conditions using all the fuel you still have) is not good. I would try everything to avoid that. ATC can call airfields on the telephone, airliners in the upper flight levels can contact them on your behalf, etc.

The other option, inconvenient as it may be, is to land and pick up some more fuel

If I was facing such unknown conditions I would probably do that.

Administrator
Shoreham EGKA, United Kingdom

The other option, inconvenient as it may be, is to land and pick up some more fuel. >

A very sound advice indeed! But....

you just tried to land at your primary Destination and you failed, twice!

Thus, back to my question (#06):

where would you go now, Peter, "to pick up some more fuel" (to your "preferred" or to the filled alternate )?

PS PREVIEW POST button appears not to be working?

PPS How do I "finish" a quote that I started with >. ?

YSCB
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