Low Cloud
 

How low can you go? Avoiding the clag would be hard most days if we stick to the VFR flight rules so what should we do for avoiding cloud on those days when cloud base is 1000ft or less, stay in the hangar and talk it through or just jump in and go low level?

I always thought that if the birds are walking then I will stay on the ground. I`ll have a look at the books tonight, must admit I hadn`t thought about it before and just assumed that as long as I stayed below cloud base I`d be ok.

You must remain 500 ft clear of cloud unless on a special VFR clearance or have an IMC rating. You must also respect rule 5 (500ft from structures etc)
Stay in the hanger. Remember when the ground goes up the cloud doesn't.
DO

stocker,

If you do your flying in Scotland I am amazed that you "hadn`t thought about it before and just assumed that as long as I stayed below cloud base I`d be ok.".

Personally, unless I'm just doing circuits, I have a 1500' absolute limit, (or 1000' above the highest ground anywhere near my flightpath). Anything less and you stand a good chance of flying too low over a built up area or within 500' of property, people etc.

Do you?

Personally, I would not fly lower than about 700ft - the 500ft above people etc rule is the problem and (if you get reported) that is what will get you.

One needs to be sure of where one is when doing that, because a gap of 700ft between cloud and terrain is awfully small and could close up, and then you are stuffed. Quite a lot of people get killed doing that.

Question answered, saves me looking tonight.

I remember being sent out to practice bad weather circuits as a student with a cloudbase of about 800ft, a bit tricky to stick to the rules there. I also remember making the mistake of doing the circuits at the normal speeds and becoming overwhelmed quite quickly, it was nice to get back on terrafirma.

Good advice DO, stay inside....

Pulse....

to be totally honest I had thought about it before and like many others found flying in Scotland meant it would be wise to do an IMC but alas I dont always remember everything I learned.

Clear as mud.....

ok I got the bit about the 500ft rule both cloud and people so lets just say for example I am operating out of a farm strip and I own all the land around the circuit pattern, can I do a circuit at 100ft if the cloud base is at 600ft?

And does that mean that at any other airfield/port that I would need at least 1000ft base plus an allowance for building heights in the circuit?

Im confused.....:confused:

Below three thousand feet the VFR rules state that you should remain clear of cloud and in sight of the surface. There are no cloud separation rules below three thousand feet. The 500 feet from persons, vessels, vehicles or structures, is absolute except in the case of towns, cities, villages, settlements or gatherings of more than 1000 people, where it is 1000 feet

The testing of this question is probably the single largest cause of fatal accidents.

Assuming you are VFR, a PPL, less then 140 kts in an aeroplane, the UK law says you could operate over the sea or a known empty field at a ceiling of less than 100 ft and viz of 3 km. You are VFR (Clear of Cloud and 1.5 km viz), You meet your PPL viz limit (3kms), and you are more than 500 ft from people or structure. What is legal is not necessarily safe and this would certainly fall into the very unsafe camp.

Pulse1's 'greater of 1500 ft or 1000 feet above highest terrain nearby' is a reasonable limit for a flight away from the local area.

Taking into account that any obstacles below 300' doesn't appear on the chart, min needs to be 800' agl (watch for spot heights) and dog leg if you need to.
Look at the wind direction, if it is vearing as you continue, is will get worse - probably flying into a front.
Also, wind from the left won't be too good either.

meiklepap/IO540
Got the bit about 500ft clear of cloud wrong, apologies. However flying in Alba outside the circuit with 1000ft cloudbase is a no no. Guaranteed the weather 2 miles in some direction will be worse.

It is legal to fly along at 3000 ft, at <140kn above a broken layer of cloud provided you can see at least one blade of grass. You could be 1 foot under a solid overcast. Obviously this would not be sensible, as you would have no chance to exercise see and avoid.

The VFR minima allow flight in some very unpleasant conditions. It is up to the PIC to decide if his expertise and his aircraft equipment are up to the job on any given day. I often find that with a low scattered cloud base it is much safer to get above it and fly in the smooth air with plenty of margin above minimum safe, this can often be done VFR. The risk in this is the cloud may thicken and you need to be ready to get down through a hole if need be.

Rod1

Depends on circumstances,

As stated, under 3000' you just have to be clear of cloud and observe the 500' rule. my airstrip is three miles from the coast with easy landmarks and no hills nearby. I've taken off from elsewhere in the past with very low cloud, knowing that I can fly along the coast at 500' or less and turn in to land with no problems. It helps that as an ex glider pilot, in a very slow STOL type I'd be happy to land in any available space if things deteriorated. In something faster and less STOL I'd simply revise my minima.

SS

Common Sense
 

Depends on the your experience and local weather.

Before I got my IMC rating I once flew under a load of 500' cloud but over the sea (less aerials) and vis was OK and weather at Southend was cavok.

Locally I don't mind doing circuits with a 1000' cloud base but why take a risk doing any more. IMC is a good skill but the scenery sucks once you can't see the wing tips and if you don't have an IMC or IR then its just a silly way to die.

Stay in the hanger and relax and live to fly another day.

The 500 foot rule doesn't apply:
I've got an IMCR, but I won't fly if the forecast cloudbase is less than 1000 foot above ground for the whole journey. That's because the cloudbase may be (often is) lower than forecast, and it's rather boring anyway. It's fine being VFR on top, but most places I go don't have instrument approaches, and I really don't want to descend through cloud except on an instrument approach unless I know I'll be able to see by 1000 foot above anything to bump into.

Rod, above 3000feet you require 1000 feet vertical and 1500 metres lateral separation from cloud for VFR flight. One of the reasons for this is so that in the event of engine failure, a descent through cloud does not have to follow, ( with no AI) and gives time to glide through the hole through which the solitary blade of grass can be seen , so one foot above a broken layer would not be legal VFR. (unless climbing or descending, which arguably you could keep doing indefinitely!)

However the one foot would be legal if IFR, even on a basic PPL with no intrument qualification (if otherwise meeting VFR weather criteria) and provided that 1000 foot above obstacles within 5 miles of the aircraft is maintained . Thus in good weather, above three thousand feet, set 1013, follow the quadrantals, maintain obstacle clearance, skim the clouds, and regard yourself as IFR!

Edited to say sorry Rod , you actually said one foot below, not one foot above! :uhoh:

“Edited to say sorry Rod , you actually said one foot below, not one foot above! ”

I also specifically stated under 3000 ft!:ugh:

Rod1

Erm, well to be pedantic " at 3000 feet" However, my apologies, my mistake not yours!

Nah, you're reading things into the legislation that are not intended. VFR are designed around separation from other aircraft, and separation from terrain and obstacles. VFR apply to twins and instrument rated pilots too. You actually make the point quite well later in your post.

Fair point Bookworm. Perhaps my "theory" is an unintended benefit of the VFR rules for non instrument rated SEP pilots!

Nobody has mentioned yet the missed approach height for imc rated approaches, these may well be above the actual cloudbase your flying around in.One thing I have had to do in the past is approach imc somewhere with an atc and half decent minimum approach height then skim in under the clag to get home.

Don't follow that one. You mean a radar unit decended you lower than the approved approach?

You fly either VFR or IFR. There is no "halfway hacking it" option.

If you arrive IFR and go missed, then you have to fly the published missed approach.

If you got visual before DA/MDA why didn't you land?

If for whatever reason you went missed and doing so you are still (or again) in IMC then you have to either fly another approach (as published) or divert, as per the normal rules.

You do not go missed on an IFR approach and then duck down off the published missed approach procedure to get below cloud again, to fly somewhere visually!! The missed approach procedure is designed to avoid terrain and if you do "your own thing" off it you might well hit something.

One cannot do IFR ad hoc. One has to either fly VFR (that means being visual) or fly IFR (which means you may or may not be in IMC). The planning is quite different for the two.

There is no such thing as an "IMC rated approach". An approach is flown as published.

some airports will allow you and help you to descend imc and then resume your own navigation before being on final approach. I did not mean that you can be on approach and then bail out and apologise for being misleading.

Rod,

you said 1ft under a thick overcast was ok, does that mean then that cloud seperation doesn`t apply to what is above you?

Cloud seldom "switches on or off" at defined heights. You gradually (or suddenly) loose forward vision. What rod1 said is technically correct but I am sure he didn't recommend it. Sorry for butting in rod.
DO

Yes you can certainly do that. They need to agree to that first, and you are not really flying a "missed approach" - what happens is that you go down the ILS glideslope, or the VOR/NDB inbound track, and then break off when visual. The published missed approach does not get flown as such.

But "before being on final approach" is not really correct because it is from the final approach track that one normally breaks off when visual.

What do you mean?

At an airport with a procedure you could fly the procedure and once established VMC ask to terminate the procedure and continue to make a visual approach or break off the approach completely and depart en route. With the consent of AT I see no reason why you should not do so at any point in the procedure. For example if you arrive in the hold in IMC at 3,000 and descend in the hold to 2,000 at which point you become visual and request to break off the procedure with consent I do not see an issue. This might for example prove a useful means of making a let down whilst ensuring adequate terrain clearance and in theory seperation from en route traffic.

That aside I dont see how else AT could "allow or help you" with a descent from to IMC to VMC - for example if you were to arrive in the overhead of an airport without a procedure in IMC and descend in their overhead they are not in a position to "guarantee" any terrain seperation or seperation from other traffic any more or less than en route.

It amy be true that they will have a better idea what traffic there is below the cloudbase than you might en route (assuming you cant receive a RIS and non transpoding en route traffic beside) and it may also be true that you know very specifically where you are and therefore what terrain implications exist but you are now involved in a "home made" letdown with all the risk involved in doing so.

“you said 1ft under a thick overcast was ok, does that mean then that cloud seperation doesn`t apply to what is above you?”

No! The VFR rule I was demonstrating is;

At or below 3000 ft, 140kn or less, clear of cloud and in sight of the surface, Min 3km vis.

If you fly at 3000ft and 140kn, you can see some ground below, the vis is 3km but there is a solid overcast directly above you then you are VMC. There is no “500ft from cloud” rule. I am not suggesting this is a good idea as you have lost any hope of see and avoid if some chancer is descending through cloud with no radar service and not talking to anyone then you could be in deep dodo, but that is admittedly statistically unlikely.

It is also fine to fly at 3000ft with a broken layer of cloud below you, provided you keep the above rule in mind. It is often possible to carry out long Xcountry flights in quite poor weather and remain totally legal by using the above rule. It is however vital that you have the skill and the equipment to get you out of trouble if the weather gets unexpectedly bad.

I recently toured Scotland from the midlands on a weekend when the vis was 3k but there was NSW and nil wind. I had to use VOR to backup the nav, but again this is perfectly ok. I have also configured my aircraft so its normal cruse speed is 138kn, so I do not get a speeding ticket!

Rod1

In real life, it would be exceptionally rare to have a cloud base lower than the MEA/MSA and not so low that you would not be be on the final approach leg when you broke out.

It is relatively common for a radar equipped controller to vector aircraft to intercept an extended final approach course and descend you to their minimum vectoring altitude, at which point hopefully you are right at/under the cloud base and can see ground straight underneath you and make the couple of foot descent into VMC. This is a reasonably sensible approach when the cloud base is around 1000-1200 ft AGL

Like, to pick an example scenario at random, if it's the weekend, so there's no radar service available.

mm flynn
Look at where meiklepap stays and have a look at the chart or the MDA at the few fields with radar.
I would be surprised if there was one with an MDA below 4500ft.
Come to think of it did this not start as a low level VFR question?
DO

Thread drift... Rod , you mean that you could make the MCR01 go even faster than 138kts if you wanted to? Seriously impressive....

All of them have MDA's less than 4500. I expect you meant MSA - which goes out 25 miles or grid MEA which covers a large distance as well. The fields I looked at all seem to have Minimum Vectoring altitudes at or near the platform altitude of the approach. But, as you say this was a VFR question.

mm flynn
You are of course correct. I really should not do this at work, half the brain is elsewhere.
The point I was trying to make is you can't go far in Scotland at 1000ft
do.

“Thread drift... Rod , you mean that you could make the MCR01 go even faster than 138kts if you wanted to? Seriously impressive....”

The short answer is yes, but it is not as simple as that…

There are no figures on how to set up my kit built C/S prop on my airframe. This means I have to adjust and test, adjust and test. I have the fine pitch stop where I want it but the coarse pitch stop is too fine to achieve best performance, especially at altitude. In order to adjust and test I need a day, which is very smooth (no nasty bumps), as the aircraft does 152kn TAS (3000ft) flat out, and if I move the coarse pitch stop it will go faster (by an unknown amount). This brings up the other problem, the VNE is 162kn, which is ok, but the rough air speed is 128kn. There are certainly conditions, say above a broken layer, or on a still evening when it would be perfectly safe to cruse at 140kn plus, but it has its down sides.

My aircraft is an MCR01 Club, which has a bigger wing than an MCR01 Sportster. A well sorted sportster will cruse at 160kn (but has 30kg less useful load and needs more runway). To do this it uses a special “high speed” blade on the PV50 prop hub. I have the standard blades, but am now getting into the speed band where the “high speed” blades would be more efficient. There is no danger of my blades failing, but I am loosing performance. The importer would love to see what would happen if I fitted the high speed blades, but unless he loans me £700 worth of blades to try I am unlikely to find out!!:p

I am also getting 15lph (mogas) and I suspect that getting an extra 7 or 8kn would push the fuel burn up to 18lph+. I will probably have another play at some point, but I am having too much fun flying her long distance to go back to development right now. Over the winter I may upgrade the glass HSI to a full “synthetic vision” big screen system and maybe tweak the prop some more as well or I may just keep flying her as much as possible…:ok::ok::ok:

Rod1

Apart from being able to carry full fuel , 6 people and the kitchen sink ( none of which I ever do) I have to wonder why I put up with chugging along at a stately 135 kts at 18 gals an hour in a C206. I am gonna have to get me one of these plastic fantastics methinks......

PPL limited to VFR?
 

A number of comments have incorrectly stated that the holder of a PPL is restricted to VFR flight only. This is not strictly correct. The UK PPL(A) and JAA FCL PPLs allow flight in IMC in class G airspace as long as the pilot can still see the ground and maintains the specified flight visibility. (I,e the vertical and horizontal distances from cloud do not apply.) The NPPL does require the pilot to remain VFR at all times.

Where is this info? The Air Navigation Order - part of which is appended.

ANO Jan 2008 (CAP
PPL (A) & JAA FCL PPL
c) unless his licence includes an instrument rating (aeroplane) or an instrument
meteorological conditions rating (aeroplanes), fly as pilot in command of such an
aeroplane:
(i) on a flight outside controlled airspace when the flight visibility is less than
3 km;
(ii) on a special VFR flight in a control zone in a flight visibility of less than 10
km except on a route or in an aerodrome traffic zone notified for the
purpose of this sub-paragraph; or
(iii) out of sight of the surface;
(e) unless his licence includes an instrument rating (aeroplane), fly as pilot in
command or co-pilot of such an aeroplane flying in Class A, B or C airspace in
circumstances which require compliance with the Instrument Flight Rules;
(f) unless his licence includes an instrument rating (aeroplane) or an instrument
meteorological conditions rating (aeroplanes), fly as pilot in command or co-pilot
of such an aeroplane flying in Class D or E airspace in circumstances which
require compliance with the Instrument Flight Rules; or

NPPL
(5) He shall not fly:
(a) as pilot in command of such a SSEA on a flight outside controlled airspace when
the flight visibility is less than 5 km;
(b) as pilot in command of such a SLMG or microlight aeroplane on a flight outside
controlled airspace when the flight visibility is less than 3 km.
(c) as pilot in command of any such aeroplane:
(i) on a special VFR flight in a control zone in a flight visibility of less than 10
km;
(ii) out of sight of the surface; or
(iii) at night; or
(d) as pilot in command of any such an aeroplane in circumstances which require
compliance with the Instrument Flight Rules.

You are missing the piece which says "A pilot may not."
In sight of the surface, clear of cloud & 3km is not technically IMC therefore may be flown VFR.

Last time I read up on all this I came to the conclusion that a JAA PPL may not fly in IMC, but a CAA PPL may (there being one tiny little difference between the definition of IMC and the weather limitations on the CAA PPL, forget what the detail was now but it was weather conditions in which I wouldn't be flying anyway).