'CAT II/III' on holding point signs

[rich_g85]

Hi all,
I vacated left off runway 26 at Bournemouth on Sunday and was instructed to hold at G3 (first time doing so, normally backtrack to November). While holding I noticed the sign showed '08/26 CAT II/III'

Does the CAT II/III simply denote the type of runway I'm holding short of, or does it mean something else?

Sorry if it's a daft question, if there's a document I should be reading instead let me know!

Many thanks,
Rich

[HoweC614]

I think, and I'm sure someone will correct me if I'm wrong, but CAT II/III relates to the autoland procedures available on that runway.

Airliners have different Categories of automatic landing available to them, certain runways/airfield have differing equipment which will determine what category of autoland is available.

Chris

[24Carrot]

I believe it marks the boundary of the 'critical area' inside which your aircraft might interfere with the ILS used by aircraft on CAT II/III precision approaches.

[FlyingStone]

Exactly as 24Carrot says. In theory, during Cat II/III approach there shouldn't be any aircraft or vehicle between aircraft performing the approach and localizer (antenna array located at the end of the runway). If an aircraft is performing such an approach (either because of the prevailing weather conditions either for currency), you might be asked to hold at the Cat II/III holding point instead of the usual (Cat I) holding point.

[S-Works]

Of course if the CAT2/3 is being used in anger then you are not going to be sat at the hold in your spam can..... :ok:

[excrab]

Bose X,

That seems a rather sweeping statement. Is there any legal (as opposed to airmanship ) reason why the holder of an instrument rating shouldn't depart in weather below cat 1 minimas in a well equipped light aircraft?

[rich_g85]

Thank you for all the replies. Luckily curiosity and 'easy' questions seem to be welcome here.

And bose-x is probably right - at the time I had just landed after a solo circuit, flying under a student callsign. :)

[S-Works]

excrab, might be worth having a look at the requirements for visibility etc for Cat 1 aircraft.

[mm_flynn]

excrab,

To save looking, If CAT II approaches are in use it is likely the weather is below CAT I and above Cat II. That means either the cloudbase is less than 200 feet but more than 100 feet or the RVR is less than 550 m but more than 300 m. Remember RVR is typically greater than visibility.

So you are looking at some pretty grim weather. In the US on a private flight you can legally depart in 0 0. However, you would feel a bit of a muppet if you had a problem and needed to return to the now inaccessable airport! Hence it is not viewed as a good idea.

[BackPacker]

Am I correct in assuming that CAT II/III approaches, and thus the CAT II/III holding points, are only used when the weather is below VMC?

In other words, if I'm a PPL without an IR/IMC, do situations exist where I need to hold at a CAT II/III holding point, or otherwise need to concern myself with them, instead of the normal runway holding point?

Thing is, the meaning of the CAT II/III holding point plus the associated R/T terminology was never covered (as far as I can remember) in my training. I have so far always assumed that it would be covered in the IR.

[mm_flynn]

Am I correct in assuming that CAT II/III approaches, and thus the CAT II/III holding points, are only used when the weather is below VMC?

See Flyingstones earlier post. They are used for training approaches just like people shoot CAT I approaches for training

[almost professional]

You may find that the CATII/III holds are in use in VMC for a training Approach, crews are required to do so many for currency so in the summer months will ask to do one for practice-we do not always give them full protection but if we do we will keep traffic at the respective holding point

[IO540]

What are the departure minima in Europe, G-reg, N-reg, at a CAS airport and at a OCAS airport?

I know the US airport (N-reg) Part 91 case which is indeed zero-zero. And during my IMCR training the instructor said (FWIW) one can depart in the UK in a G-reg in zero-zero too, though this may have been for a Class G (OCAS) airport only.

I know the arrival min vis is 550m or 800m, depending on various factors like runway lighting and whether you have an autopilot, but the departure is a different thing.

However, you would feel a bit of a muppet if you had a problem and needed to return to the now inaccessable airport!

That's true, but there are other airfield scenarios where the cloudbase could be say OVC005 and the vis could be 10k+ and this makes a legal return impossible. People frequently depart in such conditions, even VFR ;) but they could not land back at the same airport. Is there ever a requirement to return to the airport of departure, in private ops?

[mm_flynn]

What are the departure minima in Europe, G-reg, N-reg, at a CAS airport and at a OCAS airport?


I just had a look and the relavent criteria for UK (and I assume EU-OPS, but have not checked) is Public Transport vs Others and then Single Engine/Multi-Engine and then multi-engine defined by takeoff performance.

The UK AIP simply says for private single engine operations that the weather needs to .. be adequate to ensure a high probability of a successful
forced landing being made should a failure of the engine occur after take-off.

In addition, the minimums need to be calculated consistent with the state of registry and need to ensure sufficient guidance to control the aircraft through the takoff roll, a rejected takeoff and a departure with an engine failure.

The lowest published number is 150m for Class A-C multiengine that can continue a departure with an engine failure on the ground and on a runway lit up like a Christmas tree.

For multi-engine public transport, all of these low viz departures will (CAT II/III excepted) require a departure alternate to be filed.

Regardless of the details of the regulations it would seem remarkably bad decision making to depart in a single with weather below that which a safe return to the field (or another very local field) could be made.

[Tail-take-off]

Cat 2/3 holding points only apply when "low visability procedures" are in force. The requirements for which are many. ATC will rarely instigate LVPs for training or recency purposes. Airline pilots will make their practice auto lands with the caveat if you don't like what its doing take over manually. It's the checks, calls & procedures that are being practiced. So unless the vis is less than 1500m and/or cloud ceiling below 200' LVPs are unlikely to be in force & cat 1 holding points will be in use.

In any case I'm sure ATC would tell VFR traffic if they expect you to use cat 2 holds.

[172driver]

Is there ever a requirement to return to the airport of departure, in private ops?

Engine or other failure shortly after t/o ?

[almost professional]

Tail-if a pilot requests the full protection for the localiser for his practice approach then within reason we will give it to him-even when CAVOK- and that requires the use of the CATII/III holds, but you are correct in that we would clear the taxying A/C to the relevant hold and explain why

[BackPacker]

you are correct in that we would clear the taxying A/C to the relevant hold and explain why

So what's the CAP-something compliant R/T that's being used then? "Taxi to the CAT two slash three holding point of runway XX and hold; practice ILS CAT three approach in progress" seems a bit long-winded to me.

[Spitoon]

Something like "G-CD, taxi to holding point B2".

[TWR]

You just hold at the lit stopbar...

[almost professional]

Spitoon has it right-for us the club A/C would get 'taxy holding point S2' instead of S1, then just reinforce that with amplification about practice ILS traffic-would not neccessarily have stop bars up for a practice in VMC

[VMC-on-top]

So, if I'm doing an ILS approach (I have an IMCR), will ATC tell me if the conditions are cat I, II or III?

I'm still not clear why the holds for the different categories are at different positions? Surely, the ILS is the ILS and if the position of holding traffic has some effect on the accuracy of the ILS then all holding traffic should be at the safer (further away from the runway) holding point - particularly when we are only talking about a handful of metres from the CAT I to the CAT II / III board?

[BackPacker]

Something like "G-CD, taxi to holding point B2".

Okay, so these holding points simply have their own designator. Fair enough.

[Human Factor]

So, if I'm doing an ILS approach (I have an IMCR), will ATC tell me if the conditions are cat I, II or III?

You will hear the phase "Low Visibility Procedures are in force". In which case, you check your minima and see if an Approach Ban applies to you. If the RVR given to you by ATC is below your required approach minima, it is illegal for you to procede below 1000'AAL or the Final Approach Fix.

I'm still not clear why the holds for the different categories are at different positions? Surely, the ILS is the ILS and if the position of holding traffic has some effect on the accuracy of the ILS then all holding traffic should be at the safer (further away from the runway) holding point - particularly when we are only talking about a handful of metres from the CAT I to the CAT II / III board?

If you think about it, the DA/visibility miinima for a Cat 1 approach (generally 200'AAL/550m RVR) allows for a manual landing. Therefore there is a greater margin of error permitted, hence the ILS protection requirements are less.

When you get into Cat 2/3 minima, an ILS becomes a necessarily much more accurate procedure so the protections must be enhanced. The protection requirements for Cat 2 or more are broadly the same with RVR minima reducing to a minimum of 75m (note that is RVR - that could potentially mean a vis of around 40m at night), depending on aircraft capability. Cat 3 certainly requires an autoland so any form of interference with the beam is a big no-no.

At some airfields, the Cat 1 and Cat 2/3 holding points are coincident. At most, the Cat 2/3 point is a few metres further back. Remember that an ILS beam at its narrowest point (near the transmitter) is only a few metres wide in itself. At certain airfields, it allows an auto-rollout down the centreline. How wide will the beam need to be to allow that?

In summary, the protections are there to allow lower minima. The higher the minima, the less protection needed. There is an element of protection with Cat 1 holding points. The other extreme is in the USA where in anything above Cat 1 conditions, the ILS beam is not protected at all.

Hope that helps. :ok:

[almost professional]

Without going into more detail than I have time for-it is more critical for the CatII/III A/C with regard to potential ILS deviations due to objects close to the runway than a Cat I because of the Minima in use, so additional protection is given to those movements

[junction34]

VMC-on-top: "So, if I'm doing an ILS approach (I have an IMCR), will ATC tell me if the conditions are cat I, II or III?"

With an IMC rating your absolute ILS minimums are 500ft and 1800m RVR, therefore you'll not be making an approach in anything less then Cat 1 conditions.

-j34-

[VMC-on-top]

You will hear the phase "Low Visibility Procedures are in force". In which case, you check your minima and see if an Approach Ban applies to you. If the RVR given to you by ATC is below your required approach minima, it is illegal for you to procede below 1000'AAL or the Final Approach Fix

My minima are 500ft AAL for a precision approach so are you saying that even though I am legally permitted to descend below 1000ft to my DA, i would be doing so illegally because the low vis procedures are in place?

This seems quite an important omission from my IMCR!!

[Human Factor]

My minima are 500ft AAL for a precision approach so are you saying that even though I am legally permitted to descend below 1000ft to my DA, i would be doing so illegally because the low vis procedures are in place?

This seems quite an important omission from my IMCR!!

Yes, however read on.

The legal position is this. Your RVR minima is 1800m so in your case, if the ATC transmitted RVR is less than 1800m, you are not permitted to descend below 1000'AAL or the Final Approach Fix on an instrument approach.

In practice though, the maximum RVR which is transmitted is "greater than 1500m" so keep an eye on the ATIS or Actual Weather. It is then for you to decide whether you want to operate within the requirements of your rating or not. If in doubt, ask ATC what their visibility is and be aware that visibility and RVR are not the same thing (it depends on whether it is day or night and whether the runway has high intensity approach lighting - during the day an RVR of 1800m would equate to vis of about 1200m with HI lighting).

Therefore, you should never find yourself in that position.

[Sir George Cayley]

I'm beginning to bore even myself with pointing at CAP168, but that's where you'll find some helpful info.

For distances from the runway in different categories of operation have a look at the tables in Chapter 3.

The interesting question one should now pose is why they are what they are?

With lateral accuracy better now than when ILS was first deployed and the benefit of GPS approaches enhanced with EGNOS soon, is the 137m at the CAT ll/lll relevant in this day and age?

The Localiser Sensitive Area (LSA) has to be protected as lumps of metal can cause the ILS to wobble a tad. If the signal is coming from space.....?

But for PPLs both new and old, having an appreciation of what the weather is and the effect on ops, and hence which hold is in use, could stop an embarrassing runway incursion.

Good question and some good debate without the usual "ahem" problems.

Sir George Cayley

[Spitoon]

As Sir George mentions, CAP168 will give you plenty of relevant information. The location of holding points is also determined by the requirement for protection of the Cleared and Graded Area and the obstacle limitation surfaces, the latter itself being determined by the length and fin height (usually) of the aircraft and the pavement geometry. One of these will be the dominant factor which sets the location that must be used - all the details are all in the book. Suffice to say, designing an aerodrome is a pretty skilled task and there are many, many variables that need to be taken into account!

Fortunately for pilots, in the UK all holding points on an aerodrome will have a unique identifier and ATC will state which one to taxi to....and the aircraft should not go any further until specifically cleared to do so regardless of weather conditions or the category of approach procedures that you may think are being used by approaching aircraft.

[west lakes]

A view from the flight deck during a Cat III autoland

http://i225.photobucket.com/albums/dd161/west_lakes/aviation/emafog.jpg

[IO540]

What would you say the vis was? Looks like 50-100m to me.

I thought below 75m they cannot land because they cannot taxi around afterwards - is that true?

Regardless of the details of the regulations it would seem remarkably bad decision making to depart in a single with weather below that which a safe return to the field (or another very local field) could be made.

Not sure I would entirely agree, if based at any of a good number of UK Class G airfields ;) Unless one regards LHR or LGW as the alternate, which I suppose I would if I was on fire.

It comes down to the old chestnut of the risk of engine failure, and this leads to a debate re any flight above an area of low cloud... no difference really between a OVC002 departure (whether you call yourself VFR or IFR is a separate issue) and flying at FL150 when the bases are OVC002 down below.

I was interested in the legal departure minima, N-reg in my case, for a Class G or a Class D airport, in Europe. I think in Class G it is zero-zero. A Class D airport will have its own minima for all classes of ops, and what are they? The relevance of legal departure minima is that if you bust them, you might get done for it.

[Human Factor]

What would you say the vis was? Looks like 50-100m to me.

Count the centre-line lights. They look like they're standard 15m spacing (that'll give you an approximate RVR by the way - I make that 75m ;)).

For VMC-on-Top and anyone else, if the opportunity ever presents itself to ride in a simulator for a Cat 3B, no DH approach in minimum RVR conditions (the aforementioned 75m), do it. It's a serious eye opener. There is no legal requirement to see anything from the flight deck!!

The 75m requirements is there so you can find the turnoff and the emergency services can find you. :eek:

[west lakes]

What would you say the vis was? Looks like 50-100m to me.

I thought below 75m they cannot land because they cannot taxi around afterwards - is that true?

I think it was less than that! Warlier in the video the approach lights come visible just after the autoland announces 100ft.
I actually drove along a road the crosses the approach about 1 hour prior to the video being made, it was not good!

[Human Factor]

75m RVR with that lighting equates to about 50m vis. Interestingly, you're allowed to convert a vis to RVR (with certain provisos) but you're not allowed to convert an RVR to a vis.

[west lakes]

They look like they're standard 15m spacing

Yes they are, checked later in the video 6 are clearly visible.

[flybymike]

With an IMC rating your absolute ILS minimums are 500ft and 1800m RVR, therefore you'll not be making an approach in anything less then Cat 1 conditions.



Whilst the 1800 metres is mandatory, many years of discussion on this, and other forums, have concluded that the 500 feet is a recommendation only, and that full IR privileges apply to an IMCR for DH purposes

[SNS3Guppy]

That seems a rather sweeping statement. Is there any legal (as opposed to airmanship ) reason why the holder of an instrument rating shouldn't depart in weather below cat 1 minimas in a well equipped light aircraft?

One should have either the capability to return to the departure field (with a usable approach and weather above the minimums for that approach), or a takeoff alternate field nearby with weather above minimums.

[IO540]

Reference?

[VMC-on-top]

Whilst the 1800 metres is mandatory, many years of discussion on this, and other forums, have concluded that the 500 feet is a recommendation only, and that full IR privileges apply to an IMCR for DH purposes

An interesting view. Any further information how this has been concluded?

[Helen49]

As nobody has mentioned it, I will! The Cat II/III runway holding points mark the boundary of the Localiser Sesitive Area (LSA) within which neither vehicles nor aircraft are permitted when aircraft are making ILS Cat II or III approaches.

Notification that Low Visibility Procedures (LVPs) are in use is the indication to pilots that the ILS is protected from interference by aircraft and vehicle movements. The size of the LSA is the primary reason why aircraft movement rates are significantly reduced when Cat II/III procedures are taking place.

The holding point closest to the runway is either a Cat I or a Visual holding point.

[junction34]

flybymike: Whilst the 1800 metres is mandatory, many years of discussion on this, and other forums, have concluded that the 500 feet is a recommendation only, and that full IR privileges apply to an IMCR for DH purposes

I understood the +200ft increase on System Minima/OCH to be recommended, but the 500ft DH / 600ft MDH to be absolute for IMC Rating holders.

[IO540]

An IMCR holder can fly down to the published minima, same as an IR holder. This has been done to death and even the CAA have confirmed it.

However, the 500/600ft bit does apply in certain situations:

- In the IMCR exam (the paper was drafted by somebody who did not know the law) ;)

- On the IMCR fligh test (comment as above).

[junction34]

Thanks IO540, I've re-read the AIP and can see where that difference comes from.

I guess they mean: It's recommended to add 200 feet, and even if that gives you a DH of 450ft, it's recommended to use an absolute minimum of 500ft.

They could have made it slightly clearer!

Still, Cat 2 and 3 approaches are not going to be flown by IMCR holders as the 1800m bit is mandatory.

[Human Factor]

Whilst the 1800 metres is mandatory, many years of discussion on this, and other forums, have concluded that the 500 feet is a recommendation only, and that full IR privileges apply to an IMCR for DH purposes.

CAP168 refers and provides a link between RVR and DH/DA. In practice, you can probably operate to whatever DH you want (although 200'AAL would be the sensible absolute minimum - ie. Cat 1). However, as the RVR is always overriding, there are few situations where you would find an RVR of 1800m, especially in a light aircraft, where a DH of 500'AAL wouldn't work.

[IO540]

The key bit to appreciate is that you will never get busted for busting a cloudbase minimum (you may get killed) because the authorities have no way of knowing when you became visual with the runway environment.

Only in a multi-crew scenario is a prosecution possible, because (I understand) a pilot not flying is supposed to report the pilot flying if the minima were busted (I doubt they do, of course).

But you can get prosecuted for busting the visibility minima, because ATC knows the figure.

On the approach, you have the "approach ban" which is clear - except ATC don't know, at that point, whether you are 550m or 800m or whatever the autopilot-dependent variation is, but if you bust the lower figure they are supposed to file a report.

I think that it is even more obvious than that, though, because if the vis is below the 550m the ATIS will say something like "Cat 2 procedures in operation". I have had this only once, going to Dortmund in Germany. Obviously I diverted. The cloudbase was also BKN001 but I don't think that was what triggered the Cat 2 procedures. Maybe somebody familiar with the ATC rules can comment, but the answer may be country dependent.

On the departure, ATC will simply not allow you to depart (not sure this always applies in Class G airports) :)

[MIKECR]

What has Class G airports got to do with it? The departure minimum's(for public transport flights) depend on the runway lightings facilities(centre line/edge lights etc) and whether its darkness or light. Non public transport flights can pretty much please themselves(dependent on a number of factors - state of registry of a/c to name one) what departure minimums they want to apply themselves. Common sense however should prevail.

[IO540]

MikeCR

Are you saying that I can file an IFR departure flight plan from say Bournemouth, with the vis in the ATIS being 200m, and ATC will let me go?

I don't know, which is why I am asking you.

[MIKECR]

3.4 Determination of Take-off Minima
3.4.1 The take-off minima must be selected to ensure sufficient guidance to control the aircraft in the event of both a discontinued takeoff
in adverse circumstances and a continued take-off after failure of the critical power unit.
3.4.2 For an aircraft flown for the purpose of Public Transport, it must be ensured that take-off minima calculations are:
a. In accordance with the procedures and requirements of the State of Registry of the aircraft; and
b. not less than those required in the following paragraphs.
3.4.3 For an aircraft being flown for a purpose other than public transport, it must be ensured that, the take-off minima selected have
been calculated in accordance with the procedures and requirements of the State of Registry of the aircraft. In addition, it is strongly
recommended that the take-off minima selected should not be less than those given in paragraphs 4.1 or 5.1. It should be noted that the
weather minima limitations in pilot licence privileges may override some of the calculated minima.
3.4.4 For night operations by helicopters conducting public transport, some ground lighting must be available to illuminate the Final
Approach and Take-off area (FATO) and any obstacles unless otherwise agreed by the CAA

4 Aerodrome Operating Minima - Aeroplanes
4.1 Take-off
4.1.1 Single engine aeroplanes
4.1.1.1 The minima for take-off by single-engine aeroplanes when flying for public transport are 1000 ft cloud ceiling and 1800 m RVR.
4.1.1.2 The minima selected for all flights by single engine aeroplanes should be adequate to ensure a high probability of a successful
forced landing being made should a failure of the engine occur after take-off.
4.1.2 Multi-engine aeroplanes operating in accordance with Performance Class A.
4.1.2.1 For multi-engine aeroplanes with performance such that, in the event of a critical power unit failure at any point during take-off, the
aeroplane can either stop or continue the take-off to a height of 1500 ft above the aerodrome while clearing obstacles by the required
margins, the take-off minima must be not less than the RVR/Visibility values given in Table 2:
Table 2 - RVR/Visibility for Take-Off
Note 1: The higher values apply to Category D aeroplanes.
Note 2: For night operations at least runway edge and runway end lights are required.
Note 3: The reported RVR/Visibility value representative of the initial part of the take-off run can be replaced by pilot assessment.
Note 4: The required RVR value must be achieved for all of the relevant RVR reporting points with the exception given in Note 3.

Nil (Day only) 500 m
Runway edge lighting and/or centre-line
marking
250/300 m (Notes 1 and 2)
Runway edge and centre-line lighting 200/250 m (Note 1)
Runway edge and centre-line lighting and
multiple RVR information
150/200 m (Notes 1 and 4)

[IO540]

So, for non-PT flights, N-reg or G-reg, we seem to have, in the UK:

3.4.3 For an aircraft being flown for a purpose other than public transport, it must be ensured that, the take-off minima selected have been calculated in accordance with the procedures and requirements of the State of Registry of the aircraft.

and

(referring to runway lighting)

Nil (Day only) 500 m
Runway edge lighting and/or centre-line marking 250/300 m (Notes 1 and 2)
Runway edge and centre-line lighting 200/250 m (Note 1)
Runway edge and centre-line lighting and multiple RVR information 150/200 m (Notes 1 and 4)

So it sounds like you can depart from a farm strip in 500m (let's ignore the fact that nobody will be around to measure the vis there) and about 300m from a lit runway.

Anybody disagree?

[MIKECR]

IO540,

Assuming your operating a private SEP then the key points i'd be interested in are :

3.4.3 For an aircraft being flown for a purpose other than public transport, it must be ensured that, the take-off minima selected have
been calculated in accordance with the procedures and requirements of the State of Registry of the aircraft. In addition, it is strongly
recommended that the take-off minima selected SHOULD:= not be less than those given in paragraphs 4.1 or 5.1. It should be noted that the
weather minima limitations in pilot licence privileges may override some of the calculated minima.

4.1.1.2 The minima selected for all flights by single engine aeroplanes should be adequate to ensure a high probability of a successful
forced landing being made should a failure of the engine occur after take-off.


Table from 4.1-

Nil (Day only) 500 m
Runway edge lighting and/or centre-line
marking
250/300 m (Notes 1 and 2)
Runway edge and centre-line lighting 200/250 m (Note 1)
Runway edge and centre-line lighting and
multiple RVR information
150/200 m (Notes 1 and 4)

Note 1: The higher values apply to Category D aeroplanes.
Note 2: For night operations at least runway edge and runway end lights are required.
Note 3: The reported RVR/Visibility value representative of the initial part of the take-off run can be replaced by pilot assessment.
Note 4: The required RVR value must be achieved for all of the relevant RVR reporting points with the exception given in Note 3.

[mm_flynn]

So it sounds like you can depart from a farm strip in 500m (let's ignore the fact that nobody will be around to measure the vis there) and about 300m from a lit runway.

Anybody disagree?

And if you are in a multi-engine aircraft, that can make the prescribed climb profile from an engine failure in the take-off roll, and have filed a departure alternate (somewhere within 1-2 hours depending on how many engines you have) this would be perfectly legal for a public transport flight on G or N (or probably any other).

.... Unless the airport is closed.

And for example Blackbushe notify themselves as closed in this type weather. This procedure was introduced after a (KingAir IIRC) crashed from the climb out in low visibility.

[excrab]

Bose X

Sorry it's a while since I had a chance to get on here. I still stand by my comment, there is no legal reason why an IR holder in a suitably equipped light aircraft, on a private flight, should not depart when cat 2 or 3 holding points are in use.

I know the minimas for cat 1, 2 and 3 ILS approaches having been trained to operate to all of them at various times in my flying career, and that minimas change for aircraft categories A, B, C and D. Not sure what a cat1 aircraft is, though (unless you mean an aircraft operating to cat 1 limits on a precision approach) and can't find it's take off minima, so I would be very grateful if you could point me at the appropriate legislation, as most other posters seem to agree with me.

Thanks.

[S-Works]

Read the rest of the posts on here. They contain the information that you seek. The visibility requirements are laid down.

Your average Spam Can is a Cat 1 aircraft where IFR equipped. I have never seen a light aircraft with a greater than Cat 1 capability.

Reckless endangerment also comes to mind.

[SNS3Guppy]

Departing with the weather below landing minimums is acceptable if you have a plan; a takeoff alternate and the means to get there, and an aircraft capable of handling the conditions.

[excrab]

Bose X

I have read the posts here, especially post 51 which gives take-off minima and clearly states that with no runway lighting the lowest recommended take off minima is 500 metres.

At any airport with cat 2/3 approaches, in such conditions LVPs would be in force and the cat 2/3 holds would be used. So there is still no legal reason why the original poster if he held an IR should not be using the cat 2/3 holds for real.

As far as I was aware the cat 1 minimas only apply in very specific circumstances - that for a cat 1 ILS with absolute minimum RVR of 550metres and decision height of 200 feet. It has nothing to do with any other type of approach or anything to do with take off minimas.

As was pointed out by SNS3Guppy there is no reason that you cannot depart with less than 550 metres RVR if you have a plan. I will not argue with you if you suggest that it would be foolish to do so in a single engine aircraft, but the question I have raised is of legality, not of airmanship.

[IO540]

there is no reason that you cannot depart with less than 550 metres RVR if you have a plan

How is "if you have a plan" legally defined?

Everybody has a "plan" - it might just be a bit suspect :)

There is definitely no legal requirement to be able to return to the aerodrome of departure, for private flights, in Europe or USA. If there was, an instrument capable would not be able to depart from most of UK's smaller airfields for much of the year. Already, about 50% of the trips I scrap due to wx are scrapped because I would likely not be able to get back home above the IAP minima.

And I imagine the same situation arises in the USA. The difference is that out there you have to file an IFR flight plan if you are going to penetrate IMC (even if the IMC is wholly in Class G airspace, where ATC cannot provide an IFR clearance) whereas in the UK you don't need to.

The way all this reads to me is that legally you can depart IFR in 300m vis, and it is unlikely that the ATC at any airport would stop you, but they might stop you below 300m. I know Cat3C arrivals need 75m for taxi and perhaps this would be the min vis enforced. I am sure some big-airport ATCO can answer this.

[SNS3Guppy]

There is definitely no legal requirement to be able to return to the aerodrome of departure, for private flights, in Europe or USA.

Actually, there is a requirement to be able to return to the airport of departure. If that's not possible, one must file a takeoff alternate.

That's the point, really. One can depart, but if one can't return, one must have a viable alternate to which one can return with an hour's flying time (two hours in certain circumstances), in still air. One must also have the fuel and reserves to make that alternate.