Landing performance at alternates

[Flyingmac]

I hate cats.

[Timothy]

Pete,

You can't have it both ways. The OP was about VFR. I gave the OP a full answer about VFR.

You started talking about IFR, and talking bollox while you were about it.

Then, when I question you on your premise, you accuse me of willy waving.

I am not convinced that you have helped the OP.

[Keef]

Wie magst Du Deine Rednerei!

The thread drifted, as they do all too often. Pete mentioned the IFR 1-2-3 rule, which Timothy informed us was far more restrictive than the JAR/EU Ops (" I reckon 100' above decision altitude is fine."). Despite that, it's still the FAA IFR "alternate rule" that Pete and I were taught. I don't think anyone (apart possibly from Timothy) disagrees.

I gave what I thought was a reasoned answer to the OP on page 1, avoiding commercial ops, WAT, MEDAs and the rest.

[bookworm]

The thread drifted, as they do all too often. Pete mentioned the IFR 1-2-3 rule, which Timothy informed us was far more restrictive than the JAR/EU Ops (" I reckon 100' above decision altitude is fine."). Despite that, it's still the FAA IFR "alternate rule" that Pete and I were taught. I don't think anyone (apart possibly from Timothy) disagrees.

Well I certainly disagree. The Part 91 rule is quite clear: an alternate is required if the destination is forecast to be worse than 2,000 ft and 3 SM for +/- 1 hour of ETA. If an alternate is required, the weather minima for the alternate are 600 ft and 2 SM for an airport with a precision approach, 800 ft and 2 SM for an airport with only a non-precision approach, unless higher alternate minima are published.

That is more restrictive than the corresponding UK/ICAO rule for private flights: either your destination or alternate must be above aerodrome operating minima. To be perfectly honest, if you played at the edge of that one regularly, you wouldn't live long.

What Pete said was:

Meaning that at your proposed alternate the weather forecast should be at ETA + or - 1 hour,'1' , '2' ceiling should be 2000ft and '3' vis should be 3 SM

That's wrong, and would be much more restrictive.

[Keef]

I'm not disagreeing! The 1-2-3 rule is the "alternate rule" - ie "an alternate is required if...".

[PortAndCheese]

I'm with bookworm. As I said earlier today, the 1-2-3 thing describes when you don't need an alternate.

But I'm still waiting for the bit that links this back to our EASA/JAA PPL VFR scenario the OP began with! No legal requirement for alternate, but good practice to do as he described, and certainly good airmanship.

[Skyhawk-N]

.

[Pete S]

C Crispy:

Please disregard my post re the 1-2-3 thingy.

Clearly it applies to USA land, refers to IFR and doesn't solve your question of over egging the alternate pudding one bit.

And who needs statute miles when we have perfectly good kilometres to peer through.

Peter

[421C]

For anyone interested, pages 2-5 of the article here: http://www.pplir.org/images/stories/ppl ... 20v133.pdf
describe the FAA, UK ANO and EU OPS weather planning rules for IFR in some detail.

You say this based on what? The only reason I ask is I'm interested to hear how long have I got to live.

I think what BW is referring to is that a reasonable interpretation of the applicable rules for a private G-reg aircraft for destination and alternate weather (both planning rules and continuing in-flight) can be surprisingly non-restricting.

Firstly, as BW say, only one of your destination or alternate needs to have weather forecast at or above the "specified" operating minima. Secondly, note that cloud ceiling is not one of those limiting minima, only RVR/Visibility is.

In principle, imagine a flight to an airport in the south of England with an ILS. The minima applicable to you could be 550m RVR if you have the right AP and the airport has full approach lighting. You might be able to legally depart on an IFR flight to that airport as long as its forecast RVR was 550m or greater, even if the cloud base was forecast OVC 100' and every other airport in the south or anywhere within your fuel range, including your filed alternate, was forecasting zero-zero. It's a pretty extreme example, and to an extend dependent on how you interpret some more general text about a commander's responsibilities in the ANO. But I think BW's point was a fair one - that exercising the full flexibility that could be read into the letter of the law would be an unwise and high-risk practice.

[bookworm]

To be perfectly honest, if you played at the edge of that one regularly, you wouldn't live long.

You say this based on what? The only reason I ask is I'm interested to hear how long have I got to live.

Very much as C421 says. I don't believe you "play at the edge of" the letter of the law. Bear in mind that the only reason you need an alternate under UK law is if you want to start or continue a flight when your destination is below minima. It's not, as it is under Part 91, a contingency in case the forecast for above-minima conditions at the destination turns out wrong.

The ANO requirement for an alternate only came in after an ICAO audit a few years ago. Prior to that, there was no legal requirement other than the broadly worded requirement to carry enough fuel for reasonably predictable contingencies.

For what it's worth, though I believe that some commercial ops rules (EU-OPS etc.) are quite inappropriate for private flying, and I will defend your right to take the risk if you choose, I'm chicken when it comes to alternates, and I can't imagine launching without enough fuel to get me somewhere with 600 and 2.

[CaptCrispy]

Perhaps a little drift from my original post, but good reading as always.

I am the kind of person who likes too much rather that not enough information so I can take what I need or want from from it. Even though the 1-2-3 rule may not actually apply, I will take the idea of this (along with other feedback) to help further my knowledge and understanding, and to perhaps create my own conservative rules I am happy with.

Thanks again all.

[Timothy]

I'm not disagreeing! The 1-2-3 rule is the "alternate rule" - ie "an alternate is required if...".

...and so has nothing to do with the matter in hand. Stop digging.

[Keef]

Stop digging.

[BackPacker]

First of all, is there a specified list of approved alternate airfields or do we just choose something reasonable in terms of distance and runway length?

Next, if I have a short flight with with a single alternate (for example to Beccles with Norwich as an alternate), I usually make detailed performance calculations for both the destination and the alternate. For example using elevation, pressure altitude, temperature, surface wind, POH factors and supplements then always the CAA factors (1.43). Is this overkill or good practice.

Next, if I have a longer flight with with several alternates, for example one close to departure, one or two en-route and one by the destination, should I make detailed calculations for each of these also?

It's a good idea to think in advance about the scenario where your destination is not usable. Regardless of that's because of weather or for instance an accident on the runway. So you should always make sure you have a realistic plan B and the fuel to execute that plan. Even if that plan B is simply to return to base.

In fact, the AFE Flight Guide (at least) shows a suggested alternate for each airfield. This is typically the nearest 'big' airport with a whole host of facilities, and, more often than not, instrument approach procedures.

Whether detailed calculations are required for everything, well, I don't think so. I have done a few 'worst case' calculations and I know that for the types of aircraft I fly, 1000m is plenty in all but the very worst conditions. And there are plenty fields with 1000m runways, pretty much everywhere.

If you go to a sparsely populated area where potential alternates are few and far between, a more detailed analysis would be required.

The same goes for en-route alternates. Unless you are flying in sparsely populated areas, you are usually spoiled for choice in alternates with sufficiently long runways, fire cover, on-site maintenance and whatnot. You don't need to nominate a specific en-route alternate, and don't need to do specific performance calculations.

Which airfield eventually becomes your alternate will also be determined by the reasons for the diversion, and the larger context of the flight. For a weather diversion on a bacon butty run, any alternate will do - they do bacon butties almost everywhere. But if you need to find a weather alternate on a business trip with a specific destination, good public transportation links might be a consideration. If you have a technical problem (short of an actual mayday), you might want to choose an alternate that has on-site maintenance, and so forth. (But in any case safety is the most important consideration!)

And finally, if I do have divert, what would be an example R/T sequence, changing from say Wattisham with a basic service to Norwich to divert?

Remember that R/T messages are standardized so that standard situations do not take up unnecessary airtime. A diversion is NOT a standard situation, so you'll find that the R/T will be far from standard. Once you have said something along the lines of "...diverting to XXX because of..." you'll find yourself talking in plain English a lot.

First, ATC will want to know a bit more about your reasons for the diversion. They will want to help you, but will need to know what's wrong. Is it weather, a sick passenger, a technical problem, a fuel miscalculation or anything else. Their pre-programmed response (dispatch fire cover, ambulances, ...) will depend on your problem, but also on, for instance, POB. ATC will also want to make things easy for you so if you're on an en-route frequency, they will contact the alternate on behalf of you, pass your details as far as possible, give you vectors, squawk codes and everything, before they eventually hand you over to the alternate. (Also consider that you may be outside the Designated Operational Coverage of your alternate by the time you declare your diversion, so your en-route frequency might not be able/allowed to hand you over right there and then. But they will want the alternate to know about your situation as soon as possible.)

So don't worry about standard R/T too much in situations like this. If there is something for which a standard phrase exists, use standard R/T phraseology. Otherwise use plain English.

As it happened, I was flying EGSF -> EHRD in the PH-SVN last week, when I needed to divert. I was just past the Lakenheath overhead at FL55 when I noticed the oil dipstick hatch loose. I was on a Basic Service from London Info at the time. Here are the more important messages in this context.

"London Info, P-VN"
"P-VN, London, go ahead"
"London, P-VN is just east of Lakenheath. Be advised I have a minor technical problem and I need to divert to an airfield somewhere east of my present position for a quick repair."
(... that sure got their attention. Other aircraft calling London were put on hold at this time ...)
"P-VN, London, state the nature of your problem"
...description of the problem...
"P-VN, say your alternate"
"I'm thinking of Old Buckenham or Beccles"
"Standby while I contact them. Be advised these are normally strict PPR."
...This took a while. In the meantime I pulled out my flight guide and tried to raise Old Buckenham and Beccles by radio (COM2) as well...
"P-VN, London, I cannot get hold of Old Buckenham or Beccles. They've probably closed already. May I suggest Norwich"
"Okay, diverting to Norwich"
"P-VN standby"
...
"P-VN Norwich is OK with your diversion. Squawk XXXX. Proceed Norwich your own navigation"
"Squawk XXXX, diverting to Norwich, own navigation, PH-SVN"
...
"P-VN now contact Norwich Approach on XXX.XXX"
"XXX.XXX and thanks for the service, PH-SVN"
...
"Norwich Approach, PH-SVN"
"P-VN, Norwich Approach, radar contact 10 miles south, proceed direct Norwich, say again the nature of your problem"
... loose hatch, yadayada...
"P-VN, say POB"
"One POB, P-VN"
... That's a sign they're taking this seriously...
"P-VN proceed direct right base 09, report field in sight"
"Direct right base 09, wilco, P-VN"
...
"P-VN field in sight"
"P-VN Contact tower on XXX.XXX"
"XXX.XXX P-VN"
...The rest of the messages were pretty standard approach messages...
"P-VN, cleared to land 09, vacate right when able"
"cleared to land 09, vacate right when able, P-VN"
...
"P-VN be advised the fire tender will follow you as a precaution"
"Roger P-VN"
...
"P-VN I'm going to give you progressive taxi instructions to the Saxon Apron"
... nice. I did have the flight guide out but I had rolled out further than I thought so I wasn't quite sure where I was at this time.
"P-VN, I would like to release the fire service at this time. Do you require any further assistance from them?"
"No, that's allright. Thanks for your help, guys."
...
"P-VN you now see the Saxon hangar dead ahead. A marshaller will be waiting for you."
"Thanks for the help, marshaller in sight. P-VN"

So you see it's a mixture of plain English and standard R/T messages. All handled very calmly at both ends.

(The locking mechanism of the hatch on this particular aircraft locks behind a little metal plate that's held to the cowling by two rivets. Once on the ground we found that one of these rivets had come loose, and the metal plate had rotated away. So the hatch lock had nothing to lock onto anymore. It's not an urgent technical problem, but losing the hatch would surely cost more than the cost of the diversion. And there's a small risk of the hatch striking the canopy or tail, causing even more damage. So despite the really minor nature of the problem, I'm still happy I diverted.)

[peterh337]

The most important requirement for an alternate is this



and this



and this