Lowering cloud base rising terrain

[Miserlou]

But it still requires that certain atmospheric conditions are present, all of which can be forecast.
The only uncertainty is precisely when it will occur and that is no excuse to get caught out in it.

[Fuji Abound]

"But it still requires that certain atmospheric conditions are present, all of which can be forecast."

I am glad you said "can".

It is very common along the south coast - my pet theory is it is getting commoner.

It is often forecast - rarely very accurately in terms of time or duration - and often forecast just before or even after it has occurred.

I do agree however no particulay good reason to be caught out by it though as you can see the wall of fog from some distance and are already likely to be above it. If you happened to be routing along the coast I suppose it might well "blow in" around you if you were relatively low level. IMO this would be another very good example of the right occasion to climb above - totally safe because you know it is only a few thousand feet at most, and the weather will remain as predicted north in shore.

[Miserlou]

Getting on top by remaining VMC is a much safer option although still should not be necessary.

I just remembered an incident I overheard a couple of weeks ago.

PA-28 VFR into IMC. We came on frequency when the a/c was already at 1500' and perhaps 10nm from the runway. He was getting vectors to the ILS and they were confirming the frequency. His heading was 280 (the ILS was 269). There were a number of small heading instructions, between 260 and 275 and after a pause he was asked for his current heading.
"Heading now 180!"
My colleague and I stared at each other. We concluded that this was unlikely to end well.
By some miracle it did end in a successful landing as he broke out of cloud at about 700' and got the runway in sight.

Judging from the short radio exchange after his landing I really don't hitnk he understood the gravity of his situation. He asked why he should contact the ATC unit by phone!

[Flyin'Dutch']

Hey what is 100degrees between friends!?!

M, you can not be serious when you write that you can see DFC's point of view surely.

DFC claimed that IR/IMC rated drivers litter the countryside due to being in the majority in CFIT accidents and furthermore that those rated should make a precautionary landing when they encounter weather!

Not sure what planet DFC operates on, but it seems a different one than the one the rest of us seem to live on.

[Miserlou]

DFC only quoted AOPA's report which shows one quarter of the CFIT accidents to be IMC qualified.
You've got to ask yourself why there are IMC qualified pilots in that group at all.

My experience is that the pressure of going from VMC into IMC when you weren't planning/expecting is not to be dismissed. I'd much rather take-off with 90m RVR, solid IMC all the way and a CAT 2 ILS an hour later.

Scud-running is also quite a strain. It isn't hard to imagine a pilot, after a certain period getting tired and just wanting a way out, not realizing the effort required. In this case, when a 180 is no longer an option, a precautionary landing would still be much the better option. From a human performance point of view, it is a way out and it gives you all the time in the world to work out a new plan.

The situation is much like that of the remaining engine on a twin when one fails. It takes you to the scene of the accident!

If the pilot of the twin used the other engine as a means to extend his glide range but didn't actually expect to or try to FLY on it, we might also so see a drop in multi-engine accidents.

Twins only have two engines because they NEED two. (And depending on the operation, no requirement to be able to climb or fly on one.)

The change can be made safely but one must have a good plan from the start and know how little one can get away with, chart-wise.

Don't discount the scenarios which DFC mentions either. I made a flight a few years ago where I got to 10,000', still IMC and found the trim to be frozen. Just over an hour later, I found that one of the tip-tanks' vents was also iced up and with no aileron trim to help though I was VMC on top by then. Eventually, the tip-tank did transfer it's fuel but the elevator trim meant I was still 10 kts off the speed I wanted to fly at.
Finally, I got to the destination and had to fly a full procedure NDB approach to minimums, worse than forecast weather.

Not quite finally actually. Finally came a week later. One of the fuel tanks had a collapsed rubber cell. I'd landed with a lot less fuel than I thought I'd had and had come too darned close to needing it!
Made me think very hard, that did!

[justsomepilot]

Miserlou, what was the OAT gauge reading when you found the trim frozen?? If you are in freezing conditions, things might freeze up and are more likely to do so on a plane not designed for known icing.

There is so much nonsense written on this forum!

I just hope that anybody that reads it has a 50kg bag of salt, and a big scoop with which to empty it every time they come in here.

[Flyin'Dutch']

M,

Yes even IMC and IR rated jockeys come to grief in IMC and icing as do twin pilots in twins when they have an engine failure.

The notion though that this means that you should make a precautionary landing upon encountering IMC or best just fly with one engine to start off with is non sense.

[Miserlou]

Justsome,

Things will also freeze if you take a wet aeroplane into sub-zero conditions as I did.

The exposure to icing conditions was less than 5 minutes; I experienced not more than light airframe icing (may have been severe if I had stayed there). The frozen trim was not due to airframe icing but sub-zero air temperature otherwise it would have unfrozen at a similar rate to the rest of the ice on the aeroplane. Trim tabs are on the trailing edge of the surface. You're in a bad way if the ice has water frozen as far back as that.

In answer to your question, the ground level temperature was around +20 C and at 10,000, perhaps -10.

I don't see the where the reference to nonsense comes in. This is very similar to the type of situation to which DFC refers.

The difference in my case was that I was departing a VFR field into a low overcast with quite heavy rain and poor viz and had filed a flight plan where I would go IFR almost immediately. I could go to 13,000' for half an hour if I needed to but could also get back to non-icing conditions (lower level) as quickly as I could get up top. That is to say the rate of climb of the aircraft would not be a factor.

That's the way I planned it, that's the way it went. Didn't actually need to go to 13,000' or descend as 10,000' was riding through the tops and there was no further ice accretion.

The two main lessons are exercise the trim to it's full extent whenever you're going to fly at sub-zero temps (to get as much oil on it as possible), and if there is a fuel discrepancy (and there were three) find out exactly why and do something about it! I put it down to fuel seeping from one tank to another and due to the position of the fuel gauge (in the forward part of the main tank) when in flight, both phenomena which I had observed in the 350 or so hours which I had with this particular aircraft at the time.

You may not have anything to learn but these experiences are very relevant to the discussion.

[Fuji Abound]

I think we should keep this discussion in context.

Operating IMC carries a higher degree of risk than in VMC - period.

The types of IMC flying vary as widely as the conditions. There are a whole range of conditions that potentially increase the risk - icing, embedded CBs, heavy rain, turbulence etc.

IR pilots operate in the range of conditions (some wisley , some less so).

Broad statistics of CFIT accidents without knowing the conditions at the time, the experience and currency of the pilot etc tell us very little. It seems banal to comment that x% of CFIT accidents happen to IR pilots when in theory ALL CFIT accidents should involve instrument rated pilots because non instrument rated pilots should not be in those conditions anyway. I appreciate this is not the reality because non instrument rated pilots may inadvertently find themselves in these conditions. In that eveident the statistics do tell us they are unlikely to perform well.

So come on lets keeps things in proportion. Yes with an IR in the circumstances orginally outlined there may still be very good reasons for not transitioning into IMC - freezing conditions, CBs, rising terrain in the climb etc., and an IR pilot might be better of landing or continuing VFR. Thats an important part of his assessment and I dont think anyone has suggested that simply because the pilot has an IR he ignores other options.

However I still find nothing here to suggest that a curent IR pilot, subject to the aircraft systems working correctly and him not encountering freezing conditions, CBs, or rising terrain, will have many difficulties transitioning IMC and nor do I find any evidence (again subject to the caveats) that he would be safer scud running with rising terrain given the circumstances the orginal poster outlined.

DFC appears to suggest otherwise and I think he is wrong. I also think he is wrong becasue the "evidence" on which he relies does not support his arguement. It may well support other arguements - but not this one.

[boomerangben]

It is interesting to see the tussles between pilots on this thread and shows the differences in training. I suspect that DFC is ex military - certainly his comments reflect my own experience (I am not military but fly with ex military pilots and crew). Military pilots have a much better handle on the risks that flying may present than do civvy pilots. They are also much better at thinking ahead, risk assessing and updating plan b. So in that context I think DFCs comments are valid. I can understand the stance taken by IO540 and one or two others, but reading between the lines, these guys are flying several hundred hours a year and are very current at class G IFR flying. But they are not representative of the average private flyer.

So back to the original post, for the average ppl by far the best option is to recognise the warning signs and turn back early. No IMC, no landing in a field, no fancy aerobatic turns. What is it they say about good pilots? Something about never getting into the position where they have to demonstrate their superior skills.

[IO540]

Boomerangben is right about some of the pilots here, which I why I dislike the blanket comments being made about a transition into IMC being dangerous.

The question is, what is the "average private flyer"? It is a low hour PPL, about 20 hours/year according to one CAA man I spoke to recently. What does this mean for our discussion? Nothing much. A PPL shouldn't be in a cloud in the first place, and if he gets into one he will probably lose it.

Perhaps you meant "average private flyer with an IMCR" or "average private flyer with an IR". I am not trying to be difficult or stupidly pedantic here, but there is no doubt that the average IMCR holder is lapsed! As is the average IR holder! How many of the instructors at your local school, who once had an IR, still have a valid IR? Almost nobody will keep an IR valid unless they fly (or plan to fly) commercially, or fly regularly into Europe and need to be able to do so IFR.

The currency of the average IMCR or IR holder (private ops obviously) is just as piss poor as the currency of the average plain PPL holder. This is because most people that hang in GA today can't afford to do 100-300 hours/year, and they can't afford to buy the nice well equipped plane which is required for safe IFR.

There are IMCR pilots (like myself) who fly IFR anytime, in IMC if necessary, and don't bat an eyelid. The issues are 0C below the MSA, etc. (so the example given with someone's elevator trim freezing is daft; if one climbs into IMC and OAT is < 0C then one can expect this, which is why 0C below the MSA continues to be a planning issue even if VMC is expected en-route) But IMC itself is a total non-event and the VMC/IMC transition might be done 10x in one short flight.

[Fuji Abound]

"There are IMCR pilots (like myself) who fly IFR anytime, in IMC if necessary, and don't bat an eyelid."


But IMC itself is a total non-event and the VMC/IMC transition might be done 10x in one short flight.


This is exactly the point I have been trying to make and why I was very careful to say with a CURRENT IR or IMCR.

I think it is wrong and misleading to suggest with a CURRENT IR trasitioning from VMC to IMC is SO dangerous even when the transition is unexpected. I bet nearly everyone who has just passed their IMC could do so safely. Whether they keep up to speed is a different matter - I think we all agree on that point.

The transition whether planned or unplanned is not in itself illegal.

[IO540]

Yes, that's correct.

[Miserlou]

IO540,
There was actually nothing wrong with the planning. With a ground temperature of +20 C and tops forecast at around 10,000 there is very little space to get icing. Unless you find a little convective cell as I did.

There is nothing wrong with having a look as long as your OUTs are in order. Mine were, and I could still go up almost as quickly as I would have gone down, performance-wise.

It's still not the alternating change from VMC to IMC and back when flying IFR. It's the change TO IMC when you wanted to remain VMC that has a higher risk.

[IO540]

Miserlou

With +20C on the ground and the very far from reliable tops forecast on F215 forecasting tops at 10k ft, this means one is very likely to get freezing before one climbs on top. Even the usually useless 2C/1000ft formula says it will be 0C at 10k ft.

The only time I would regard a tops forecast as reliable is

a) when I look up and from the holes showing blue sky above it is obvious the layer is some 2000ft thick (and with a de-iced prop I would fairly happily climb through that even if it was all freezing), or

b) I can get a Skew-T from e.g.

http://weather.uwyo.edu/upperair/sounding.html

(choose region=europe and type of plot = GIF/skew-t) and a nearby station shows (in a very recent ascent) something like this

http://weather.uwyo.edu/cgi-bin/soun...400&STNM=03354

which shows a well defined top at about 1500m. This is in effect a METAR.

Otherwise, a 10k ft top forecast could be anywhere from say 5000ft to 15000ft. The great thing about F215 weather is like ISO or BS Standards - there are so many to choose from

[DFC]

It is very interesting to note that many seem to link use of the pitot heat in imc or even flight in IMC at all with the 0C level. The pitot heat must be on when operating in any visible moisture even when VMC and it is possible for ice to form on the aircraft in VMC and in IMC when the OAT shows a tempeature above 0C.

AOPA has an online course for the Single Pilot IFR and NASA has another for Flight in Icing conditions. Both are well worth the time and are free.

As for the question about flying over Wales - If I planned a VFR flight over wales I would not plan VFR unless I could expect to be 2500ft vertically clear of cloud at cruise level during the proposed flight and any possible diversion. If I can't get that then I will plan IFR and hope that I can remain VMC to enjoy the view but it will not matter much if I can't.

One big difference bewteen the VFR flight and the IFR one would be the fact that the VFR could be based on simple DR perhaps out of coverage of navigation aids while the IFR one would require some pre-planned use of appropriate Navigation aids.

Again if anyone thinks that needing such a high cloudbase for VFR flight would mean that many VFR flights would not take place they are correct. The answer is not to lower the operating minima to suit the climate (or the cost of obtaining an IR) the answer is to stick to safe operating minima and if that means not flying then either put up with it or move to a better climate.

If I go unplanned IMC on a VFR flight, it will be Climb, 7700, Mayday call and request diversion. It will hopefully end up with my making a report of how stupid I was to get there in the first place. I will not have learned about flying from the experience I will have learned about not flying.

However, reading IO540 and Fuji Abound's comments I think that they are talking about VFR flights operated in accordance with IFR i.e. they have made all the decisions pre-flight that enables safe IFR flight by as they say "current competent Instrument pilots".

One wonders how much the GPS has changed pilot's attitudes to going IMC on a whim. When one relied on VOR and NDB as the sole means of navigating in IMC one made darn sure that one was aware of one's position at all times even if it was hard work. Of course, GPS does bolster one's confidence in being able to avoid not only terrain but also airspace but last time I checked few VFR flyers have BRNAV approved GNSS units. Even those IR pilots who did have BRNAV were not aware of the requirement to plan to stay 5nm laterally away from controlled airspace when using BRNAV as sole means of navigation in Class G.

More importantly, when flying on a VFR flight and going from VMC to IMC and back to VMC 100 times during the flight does the pilot fly at the appropriate IFR level when IMC and if in receipt of an ATS service do they notify the changes so that other flights can be warned?........or would it not be simpler to say that the flight is IFR but intermittantly VMC!

Regards,

DFC

[IO540]

If I go unplanned IMC on a VFR flight, it will be Climb, 7700, Mayday call and request diversion

There isn't much point in debating flight in IMC with a pilot who would do the above. It's fair enough for a PPL but it removes all credibility for his views on the safety of flight in IMC. It's a bit like me expressing views on transatlantic navigation of a 747.

As for Wales, I fly there fairly often for a purpose, and the problem there is that the clouds are often below the hilltops. Conditions like that are simply not flyable VFR, no matter how slow the aircraft is. They are flyable IFR but then where is one going to land? An all-GPS DIY approach, or an unofficial NDB procedure into say Welshpool? A lot of the time, Wales just isn't flyable and that's it.

[Miserlou]

IO540,

Whatever the forecast, there is still nothing wrong with looking for yourself.

It's a thinking game and when ice is thrown into the equation your actions must have a good out or plan B (and C if you like).

What a plonker I'd have been to have sat at 4,000' with tops at 6 or 8 or 9 for that matter.

I may even also have got to 10,000 still IMC WITHOUT getting any ice. You just don't know.

The aircraft I was flying can get to that altitude in less than 5 minutes which doesn't represent a high risk for climbing to have a look, especially with the high 0c level.

As it was, the conditions at 10,000 were difused tops, no horizon, just a pale shade of white and there was no further ice accretion.

I have mentioned convective cloud in an earlier post and the ice exposure was very brief. These clouds often have limited lateral extent. In freezing rain or drizzle, which you can get in positive temperatures, where you are flying along quite happily below a warm front.

There was nothing wrong with that decision.

[IO540]

I agree the decision was fine, because the freezing level was (presumably this was UK) well above the MSA so you had a way out which was to descend a bit. I do the same. What I meant was that the possibility of ice accumulation was to be expected. But it sounds like you had a turbo/turbine aircraft (2000ft/min sustained to 10k ft isn't bad!) which is something else (even if it was not "known ice" cert)

[Flyin'Dutch']

DFC,

You write that your glibly go up into IMC:

If I go unplanned IMC on a VFR flight, it will be Climb, 7700, Mayday call and request diversion.

whereas a few pages back you suggest that:

if you are an IMC holder or IR holder then only go IMC if the divert/ precautionary landing option is not available

So what is it?

You furthermore state that:

1. Your personal minima for flying VFR in the UK is that you can stay at least 1000ft under the cloudbase (for fear of aeroplanes tumbling out of that cloudbase from nowhere)

2. That people should stick to their personal minima

3. That your personal minima over Wales is 2500ft.

So what is your personal minima and can you at least on here stick to that to avoid confusion amongst us poor readers.