IMC in VFR

[arn3696]

I have performed a few searches for info on this but I cant seem to find much about it...although im sure i have seen a similar thread on pprune before.
I'll ask the question anyway...

My understanding is that if you hold an IMC rating (or an instrument rating) in the uk, you can fly VFR with the 3km rule reduced down to 1500m. If you want to fly out of sight of surface you can do that, but have to fly IFR, with the associated flight plan filed.
Although, this seems to contradict what I have seen in practice. People fly through cloud to fly 'VMC on top' on 'VFR' flights. Surely this is illegal for the reasons mentioned above. Can someone please either correct me or clarify this for me because everywhere I look I seem to get different opinions on this.

Thanks in advance

[helopat]

Not sure about the british rules but for what its worth...

Terminology of your question is a little confusing...if I unintentionally condescend, please forgive me. If you are a VFR (visual flight rules) aircraft, you should not, under any circumstances, break cloud clearance rules...not even to get to or operate in VFR on top (ie. in visual conditions on top of a solid cloud deck). Now, if you hold an instrument rating (ie. able to operate IFR in IMC) then you can file your flight plan, go flying, and operate in IMC (in cloud) or penetrate cloud to operate VFR on top.

As to what people do in practice, they might do whatever they want as long as they are prepared for the possible unpleasant consequences (ie. a VFR bugsmasher penetrating cloud, perhaps without a flight plan filed, and coming in contact with terrain, other aircraft, etc). Here in Australia, if an IFR aircraft takes off, it will be flying such that it maintains terrain clearance throughout the takeoff, cruise and landint. ATC look after making sure that it stays clear of other IFR traffic. VFR traffic (ie bugsmasher aircraft operating in visual conditions) are still see and avoid. THEY get height separation from operating at the correct VFR cruise altitude (and hopefully not on routes used by lots of IFR aircraft). VFR aircraft are supposed to maintain the appropriate cloud clearance at ALL times to keep from hitting an immovable object (mountain) or other aircraft.

Hope I haven't prattled on too much...any help?

[Mark 1]

There are several issues wrapped up in your question.

To fly VFR you must maintain VMC, which means 5km vis, clear of cloud and in sight of the surface (outside CAS and below 3000'). With an IMC rating (UK only) or an IR then flight is allowed as above without the visibility restriction.

A flight plan is not required for IFR outside of CAS on a private flight, so an ad-hoc ascent or descent through clouds, in accordance with IFR, is quite legitimate if you have the licence privileges and aircraft equipment required for compliance.

Of course, these regulations are virtually unenforcable on private, non-CAS flights, so its possible you may observe other 'interpretations'of these rules.

[helopat]

A flight plan is not required for IFR outside of CAS on a private flight, so an ad-hoc ascent or descent through clouds, in accordance with IFR, is quite legitimate if you have the licence privileges and aircraft equipment required for compliance.


Mark 1,

Is that right? You can fly IFR in IMC outside controlled airspace in the UK without filing a plan? Amazing! Here in Australia there are lots of RPT aircraft zapping around in uncontrolled airspace (little regional fields everywhere) and they've all got to file, especially when they will go into actual IMC...traffic handling is all done procedurally (very little radar coverage in the bush)...thats not to say that Bloggs doesn't take his Cessna out for a bash and go in cloud for a jolly...but if he's IMC and the Dash 8 with a flight plan is also IMC in the same bit of airspace:eek: ...you get it.

As you said, unenforceable if the VFR driver does it, but damn scary nonetheless wouldn't you agree?

[Mark 1]

Yes, it is true.

In England especially, there is good availability of radar services, and very little commercial traffic outside CAS.

I usually squawk mode C 7000, and get a radar information service for those occasions. I guess with mode S and ADSB becoming more widespread, it should afford even more safety.

Legally, a non-radio Tiger Moth could fly through the instrument approach sector of say Coventry or Gloucester (class G airspace) airports in IMC and without telling anyone. And that would be scary.

[Lucifer]

Legally, a non-radio Tiger Moth could fly through the instrument approach sector of say Coventry or Gloucester (class G airspace) airports in IMC and without telling anyone. And that would be scary.
And not to mention, very foolish!

There are also loads of RAF fields with published instrument approaches in class G, for which the same could occur.

[bookworm]

As you said, unenforceable if the VFR driver does it, but damn scary nonetheless wouldn't you agree?

Flying in IMC without an Air Traffic Control Service (in class G) is one of those aspects of flying that is perceived as a huge risk in one culture, and is standard practice in another.

In reality, your chances of being involved in a midair collision depend on the probability of encountering something on a collision course mulitplied by the probability of not seeing it until it's too late. For flying on a fine VMC day with correspondingly high traffic density, the first factor is considerably higher than in IMC on a foul day. While we assume that see-and-avoid works, in VMC the second factor is actually rather higher than any of us would like to think. Thus, despite relatively congested airspace, there hasn't been a midair collision in IMC in the UK for something like 40 years, while midairs in VMC occur at a rate of the order one a year.

The UK does have a network of radar services that provide advisory services (rather than control and guaranteed separation) outside controlled airspace. Though particpation is not mandatory, it undoubtedly further reduces the risk.

[Coldbear]

Here in Denmark, you can fly VFR on top of a cloud base, VFR without ground sight, if you have more than 150hours PIC. however there must be "good" weather at the destination aerodrome.

Martin