Pre-planned diversions for VFR flights

[FlyingForFun]

Another thread got me thinking about the idea of VFR flights and diversions, so I thought I'd open the subject up for general debate.

The written navigatoin exam which we all remember well from our training involves completing a partly-filled-in plog for a route and a diversion. My observations on planning a diversion in this way are that it is a complete waste of time, far more suitable to an IFR flight than a VFR one.

Under IFR, it is reasonable to assume that in the vast majority of cases the flight will reach its destination. However, it may be that upon reaching its destination, the weather conditions are not suitable for an approach or landing to be made. The captain will then make the decision to divert to his alternate - a course of action which can (and should) be pre-planned.

Under VFR, the situation is different. If the flight makes it to its destination, the vast majority of the time it is possible to make a landing. But there is a reasonable chance (certainly with the British weather) that the flight will never make it, and a diversion will have to be made. However, this diversion will not be from overhead the planned destination (as the PPL written exams would have you believe), it will be for somewhere en-route. So it is not possible to pre-plan the headings and times - rather, the techniques which are taught on the PPL course for making an "unplanned diversion" need to be used.

What's more, it may be that the pre-planned diversion airfield is also out of reach because of the same weather system which is preventing access to the planned destination. In this case, part of the diversion planning involves selecting a suitable nearby airfield, taking into account the current location, and the location of any weather systems. In fact, my experience is that if I do have to divert it's rarely to anywhere that I would have thought of listing as a diversion airfield before the flight.

That's my thoughts on the subject, but do you guys agree or disagree? Discuss......

FFF
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[Genghis the Engineer]

I agree, the limit to my diversion planning nowadays is to keep the Pooleys pages for anywhere I'm expecting to pass close to on my kneeboard whilst en-route. All my experience tells me that the "unplanned diversion" skills are the most important, and the ones that I use.

That said, on a long route, particularly where weather might be iffy on the way, I do make sure that there are available diversions.

G

[Grainger]

Hey Genghis - that's exactly what I did for each leg of my recent trip. Several plates on the kneeboard just in case.

Luckily didn't have to use any, but it was kinda reassuring to know they were there.

In the event a quick call to the relevant ATC unit will get you vectors and all the help you need to a safe haven - but it makes sense to plan your route to pass close to, or through the overhead of, likely diversion fields - one less thing to worry about.

[justsomepilot]

FFF, I agree. That's why one should always carry the Pooleys book, the UK IFR touring guide (if one has the instrument option, even if flying "VFR"), and of course a moving map GPS .

[FormationFlyer]

Just a couple of thoughts here.

The sentiments expressed are fine - except if you fly in scotland or wales or other places where airports are a bit thinner on the ground (no pun, ok yes it was but it was very poor so don't laugh, no please really). In this scenario fuel could be an issue so a pre-planned diversion can be useful even VFR.

The other issue is when you arrive at your destination you find the conditions are out of *your* or your aircraft's limits. Again sometimes it is useful to think ah. The runway at my destination has a significant crosswind, if it gets any higher its going to be too much - therefore If thats the case then Ill divert to blah - given this situation (and depending on ATS) you may not find out until you try to land...so its good to have pre-briefed youself about where to go.

Now in the latter case it may seem a little excessive to plan this divert, but the fact you have thought about it and formulated a plan is much better than trying to do it all in the air. By doing the thinking on the ground you reduce the air thinking significantly...giving you more mental capacity - a valuable commodity in the air.

But, back to the original sentiment - yes unless you are flying in an inhospitable area (no im not talking about the alleged reception from the locals!) it is probably easier to stick with a mental plan, and plan the divert in the air if necessary given the situation at the time.

[High Wing Drifter]

FFF,

I disagree about the purpose of the planned alternate. My view is that the planning is to take account of unexpected problems at the field that prevent you from using it. These could be a gear-up landing for example. But really could be anything that simply causes the field to be unavailable and unusable and there is no way you can assess the likelyhood. In such a case you need to think about where else to go and it is easy to that thinking when planning, esp as at that point you maybe have only enough fuel for the alternate + 45mins reserve.

The wx diversion is a different kettle of fish. This is where the unplanned diversion skill that you are tested on during the skills test comes in. By its very nature you can't account for bad weather becasue the forecast says everything will be fine and you, as the pilot, have determined a stable or improving situation and not a degrading one. Therefore, there is no plan other than planning diversions every 20nm or so (crazy!), that can account for wx problems - other than a general situational awareness of what is arround you (hills, airfields, CAS, etc) at any time in the flight.

[N5528P]

Why not plan several alternates? Not to the last detail, but having a look at the maps before the flight (and not only on your planned route) will give you an advantage if you have a diversion somewhere en route.

Of course a GPS would help and having the Facility Directory with you is no disadvantage either, but when you plan a route properly, you have a line on your map, you make airports colse to the route just to be aware.

I would consider it rather crazy if some pilot only plans for exactly the cases required by regulations.

Regrads, Bernhard