Descending through cloud without a procedure

[Dude~]

I have a question about flying on top of cloud.

Pilot takes off in good viz with a layer of cloud 2000ft above the local terrain. Pilot gets a RIS and climbs on top for some general handling then decides to descend until in sight of the surface again. If in Class G airspace, and not using any procedure, but perhaps tracking a VOR and fairly certain of location, how low can you go, assuming the cloud base had lowered since climbing on top? Is this a judgment call or should it always be 1000ft above nearest obstacle? One can well imagine the temptation to try a little bit lower. Didn't Hill crash at Elstree doing that?

Could it still be acceptable to descend below MSA if you knew exactly where you are? If you were to unable to break cloud, presumably you'd have to divert to an airport where there is an instrument approach, but would ATC give you ILS frequencies or would you have to be carrying full approach charts everytime you go on top?

Yes I do have an IR, but no I have not really used it, and frankly find the idea of using it is daunting since the training for the IR was a entirely on pre-planned school routes.

Also, if you want to navigate out of sight of the surface, but there are no radio aids suitable to track, is it acceptable to dead reckon and back up with position fixes, or should you always be tracking a radio aid?

[dwshimoda]

Dude,

I may be way off the mark here, and if I am, I apologise. But if you are out of sight of the surface, and have no radio aids to track, how are you going to position fix?

[DFC]

dwshimoda,

One could have 2 VORs, 2 DMEs and 2 ADFs but if the track is not taking you to or from one of the VORs or NDBs within useable range you can not "track" them. You can however fix your position from the information they provide.

There is also VDF for the situation of having none of the above.

Failing that most of Europe has radar and some unit can give a fix.

----------
Dude~,

The answer is that provided you can fix your position using NDB(s) within the DOC, or VORs within the DOC and 50nm of the station, with DME if available, you should descend to not lower than 1000ft above the highest obstacle within 10nm of the indicated aircraft position (The 10nm being made up of the 5nm possible error and the 5nm you have to be away from obstacles).

The best place to be just after reaching MSA in your scenario and discovering that you are not visual is back up on top again. That makes the flying easier and gives you many oportunities for;

1. Calling the radar unit you used and finding out where the nearest hole is (if any) and what the weather is at various places.

2. Spotting a suitable hole yourself

3. Diverting to a suitable place where you can either descend to a lower MSA or to the same MSA but some pilot has reported a higher ceiling. Remember Fohn effect from the met?

4. Divert (radar vectors) to an aerodrome for an SRA........if you need more than a non-precision approach then you realy did get yourself in a pickle and if that is the case then ATC will pass the procedure details to you!

If operating on a DR track of any length, the allowance gets very big very quickly. Can't remember the exact figure but from memory when leaving the last fix, the area to be considered for obstacles quickly expands to 60nm each side and at some stage (I can't remember when) to 120nm.

You say that Yes I do have an IR, but no I have not really used it, and frankly find the idea of using it is daunting since the training for the IR was a entirely on pre-planned school routes.

Perhaps you should consider the school training provided as being the correct and safe way to operate. By that I mean do not go IFR unless you have planned the trip or part of the trip IFR and have the required charts, weather and planning completed.

If you like the idea of getting above the clag in the local area then take the time in the planning stage to check out the navaids you will use to define the area once above cloud. Make sure that you have a good MSA calculated. Carry diversion charts and fuel.

Don't push your luck with descending below MSA if the conditions are not right (and that includes visibility below cloud as well as ceiling!). Shame to spend 8 to 10K+ on an IR just to make a splat on some hill.

Regards,

DFC

[dwshimoda]

DFC,

Sorry - just reaqlised the difference in what Dude said, re tracking.

Agreed.

DW.

[Dude~]

Thanks DFC, so going for a jolly on top in the local area where there are stacks of radio aids around still needs careful planning and considerations, especially re diversions.

I didn't realise Radar might be able to help with finding a hole in cloud.

Thanks for the info about obstacle clearance when dead reckoning, any idea where that is written down?

[FlyingForFun]

Dude,

This question has been discussed many times, and no conclusion ever reached.

My own belief is that, legally, you are allowed to descend as low as you like. The reason I say this because you are exempt from the 1000' rule "as required for take off and landing". So if you argue that descending below 1000' is required for landing, then it is legal.

There are many others, though, who believe that this exemption only applies for a published approach. However, there is nothing in writing which confirms this. What's more, there was a proprosal by the CAA, a few years ago, to explicitly ban unpublished approaches. Although this proposal never came to anything, the fact that it existed in the first place suggests that the author believed that unpublished approaches (which is basically what you are talking about) are legal... otherwise he would have had no need to try to make them illegal.

If you agree with my legal point of view, the next question is the practical issue of how low do you actually go. That's something you can only work out for yourself.

Yes I do have an IR, but no I have not really used it, and frankly find the idea of using it is daunting since the training for the IR was a entirely on pre-planned school routes.

My suggestion is to go and fly some routes IFR. Take foggles and a safety pilot if it's a Cavok day. If it's not Cavok, and you're happy you can get into your home airfield safely (given what we've just been discussing) then leave the foggles off, because you want to start learning what real weather looks like. It's very rare you'll fly a whole route in solid IMC, for example, although this is all the IR has trained you for.

FFF
----------------

[PPRuNe Radar]

I didn't realise Radar might be able to help with finding a hole in cloud.

The help is actually totally dependent upon either another pilot or an adjacent airfield ATC unit who is able to report a hole (assuming the radar unit is socked in) ATC radars are not that great at weather detection since we process much of the clutter out so we can see the aircraft.

[IO540]

"Yes I do have an IR, but no I have not really used it, and frankly find the idea of using it is daunting since the training for the IR was a entirely on pre-planned school routes"

Speaks volumes about JAA IR training, doesn't it. I guess you are very familiar with the approaches at Bournemouth, Oxford, Cranfield, or Cambridge?

Best to do some flying with an IR pilot, doing some airways routes. You have an IR so you can be PIC. Pick some nice destinations in Europe and he'll be more than happy to come along just for the trip

Legally, it's not illegal to execute a DIY instrument approach, in a G-reg. (There are some complications doing this in an N-reg, due to a FAR regulation whose number I don't recall off hand)

How to do one satisfactorily depends on your attitude to risk. I'd use GPS plus VOR/DME fix and descend to 500ft over the highest obstacle within 5nm. Having got QNH from a nearby proper airport and verified it against the GPS derived altitude. This rule often yields an "MDH" of 1000ft or so. I've gone below that but wouldn't do it again.

As regards a position fix, well use your common sense. If you get it wrong, you will die, so it's desirable to get it right. (Actually personally spoke to one man who did a CFIT at an estimated 120kt but the angle was quite shallow and he is still here, having spent some time in hospital).

So, two independent position fixing methods, and obviously one of them should be a GPS or radar.

If you have no nav gear, a PAR approach is the #1 choice.

Next option: you can get a radar letdown from most military (LARS) units. They do it over nearby surveyed terrain and they will take you down to 1000ft over the obstacles. You just hope to be in VMC by then.

Next option is to get VDF from some airfield (most can do this) out over the sea and descend out there. I guess D&D on 121.50 can also give you a fix over the sea; I don't know if they like doing that. Obviously if you have enough fuel then a PAR approach is better because ending up over the sea under an OVC003 limits your options to coastal airfields with offshore wind

But surely you knew all this

Anybody who flies in IMC without nav equipment, and particularly a decent GPS, needs their head examined, IMHO.

[pipertommy]

while your on the subject!

Hi all,I have a an IMC rating and it was never actually covered about minmum equipment ie nav aids required to enter IMC conditions in non-controlled airspace?I currently fly a tomahawk with ADF and VOR/ILS but its not fm immune does this make it useless?I back this up with my own GPS pilot 3.By entering IMC i only mean to climb on top!Not to cruise in IMC.cheers:

[IO540]

pipertommy

Sounds like you have been listening to one of the countless old patronising farts who make up much of the UK GA airport scene and who say things like

"the IMC Rating is a get out of trouble Rating", or

"the IMC Rating is a get into trouble Rating",

"the IMC Rating is only a get out of jail free card, young man"

etc
etc
etc

Your privileges are IFR in Class D,E,F,G in UK airspace, and that includes all instrument approaches therein, subject to 1800m minimum visibility on the ground, and you can legally fly down to the approach plate minima.

It may be an idea to fly with a half decent instructor, or an experienced IR pilot.

The problem is that a monkey can be taught to fly a plane straight and level in IMC, so saying you won't fly en route IMC doesn't really help you. The instant you enter cloud (which a plain PPL must never do, of course ) you are facing the possibility of having to stay in it for a while, and fly an instrument approach to get back down.

Even flying VMC on top (which is everybody's preference, no matter how good they are, simply because it's so much nicer) means that you may have to fly an approach to get back down.

My suggestion, which is worth what you are paying for it, is that you need to get good enough to fly the common approaches i.e. VOR, NDB/DME, ILS. An ILS is the most important because it is the easiest to fly and will get you down and save your life even in the worst conditions.

FM Immunity is required only for IFR in controlled airspace which for you and in England means Class D. In Class G you are OK. I am not aware of any actual problems ever having been reported (and never met anyone who has) however. It is a theoretical measure to prevent interference from FM radio stations near the top of the FM band e.g. 104MHz, affecting VHF navaids such as ILS and VOR. Anyway, you can fly an ILS into say Biggin but not Bournemouth, well not legally anyway. Of course the schools that fly non-FM-immune planes never go to Class D airports IFR

If you fly an NDB approach then you need a working ADF. There is some debate about this if in Class G but I wouldn't go there. What I would do is use the ADF together with the GPS though, because a 30 degree error on an ADF is common.

Similarly with DME. However any approach which says "DME mandatory" obviously needs one. Sometimes there is a radar range substitute available if you don't have a DME.

I would also carry a very good moving map GPS and spare batteries, with a remote (window mounted) antenna.

[pipertommy]

Thanks!basically what i`m getting at is doing an ILS back into Cardiff which i guess is now ruled out .I did SRA`s as part of my IMC training,would i be correct in saying i could use this as the let down?Oh and i have been told you must have two radios on board for class D or is this for flying actual airways?

[RatherBeFlying]

Lets just say that a GPS will teach you a lot about the accuracy of an NDB approach in your a/c.

You may want to have your compass properly swung after

Then go up and check it again on several bearings.

[bencoulthard]

Just a thought, which may be a crap one as I dont have IMC, is it worth practicing something which may kill you on flight sim software?

Surely its no disadvantage?

[justinmg]

Originally Posted by IO540

pipertommy
FM Immunity is required only for IFR in controlled airspace which for you and in England means Class D. In Class G you are OK.

In class G you are only ok if you don`t need to make an ILS approach . If you do, then you have to be FM immune. I have taken this up with local RADAR units and the CAA for clarification, with very little progress or understanding from anyone.

[dwshimoda]

Originally Posted by bencoulthard

Just a thought, which may be a crap one as I dont have IMC, is it worth practicing something which may kill you on flight sim software?

Surely its no disadvantage?

Ben,

I found MS Flight Sim invaluable for my IMC training - but only really for practising the holds and approaches with different winds etc. There is no point trying to fly it as a real aircraft, as there is no feel to it.

The biggest element of learning to fly IMC is training yourself to ignore the fact you feel like you are banked at 30 degrees and climbing, and set up a really good instrument scan, and even more imprtantly - believe the scan, not your senses. This can't really be done on Flightsim, apart from building your scan, although none of the gauges on my flight sim are in the same position, nor look anythig like the ones in the aircraft I use!

As part of your PPL you will do a little IMC, including how to execute a 180 turn and backtrack - try and get an instructor who will do it for real with you, rather than with foggles / hood, etc.

DW.

[buster172]

I have to agree with Dude,

There are lots of bits outside the training that aren’t covered specifically, and it appears from some of the answers there are a few things less than black and white.

Are there any experienced IR pilots out there who might be willing to take someone like Dude or myself along with them to experience some 'real' flights?

Id like to say I’ll buy coffee, tea, lunch etc for the chance to see it all and provide as much input as I can. Might it even be a benefit to the other pilot having someone who can do it alongside to share a little of the workload?

Regards,

Buster

[IO540]

Equipment requirements for UK airspace, applicable to any aircraft registration, are in schedules 4 and 5 of the ANO

http://www.opsi.gov.uk/si/si2005/20051970.htm#sch4
http://www.opsi.gov.uk/si/si2005/20051970.htm#sch5

In class G you are only ok if you don`t need to make an ILS approach . If you do, then you have to be FM immune.

I'd like to see the reference for that. If it's not in the ANO then I don't see how it works.

I saved four figures in training costs by spending many hours on FS2002, as it then was (now FS2004). One doesn't even need the yoke; a joystick is good enough because it is the procedures and situational awareness one is learning.

The IMC Rating does need a general improvement in the calibre of instructors that teach it. But one could say the same of the PPL

[rustle]

Originally Posted by IO540

The IMC Rating does need a general improvement in the calibre of instructors that teach it. But one could say the same of the PPL

You often make comments like that here, and I would (genuinely) like to know the sample-size you use to come to that conclusion.

Your earlier comment:

Originally Posted by IO540

Speaks volumes about JAA IR training, doesn't it...

was based on a sample of one.

I hope your comments about the pilot training industry in the UK are based on something more statistically significant than one? Have you a lot of anecdotal evidence or first-hand experience of lots of instructors?

While I have little sympathy for an fATPL or IR holder and/or flying instructor

Licence Type (eg CPL. Pilots only):
Frozen ATPL
Current a/c Type (eg B737. Pilots only):
PA28
Location:
Southern England
Occupation:
Flying Instructor

who doesn't know the "rules" about, or procedures for, descending through cloud, I think some of the throw-away comments are unnecessary too.

Just my 2p.

[Brooklands]

buster172,

Are there any experienced IR pilots out there who might be willing to take someone like Dude or myself along with them to experience some 'real' flights?

If you wander over to the flyer forums, and contact Timothy* I belive he offers to do this for people, as do one or two others.

Brooklands
*He does post here from time to time, but you'll get a much quicker response via the flyer forums.

[justinmg]

Originally Posted by IO540

Equipment requirements for UK airspace, applicable to any aircraft registration, are in schedules 4 and 5 of the ANO
http://www.opsi.gov.uk/si/si2005/20051970.htm#sch4
http://www.opsi.gov.uk/si/si2005/20051970.htm#sch5
In class G you are only ok if you don`t need to make an ILS approach . If you do, then you have to be FM immune.
I'd like to see the reference for that. If it's not in the ANO then I don't see how it works.

The actual issue comes down to interpretation of table 2 of schedule 5. I have tried to get `round this` by interpretation, espescially as FM inteference is more of a theoretical problem than a practical one. Anyway.....it may force us all into flying with correctly equiped aircraft, which is a good thing.
http://www.caa.co.uk/default.aspx?ca...90&pageid=5866