VFR / IFR Inflight Minima

[sarboy w****r]

Hi All,

I'm trying to get my head around the minimum in-flight met conditions that are permitted for IFR flight for non-AOC flights (which clearly will have limitations imposed by an ops manual). I'm hoping that all those with their heads in the books might have an opinion that they'd care to share, hence this forum.

CAP 393 (ANO & Rules of the Air Regs) (http://www.caa.co.uk/docs/33/CAP393.pdf) is the relevant reference. Section 2, Rule 28 defines VMC, and if VMC doesn't exist then you must fly IFR.

28 (2) Subject to paragraphs (3), (4), (5) and (6), an aircraft flying outside controlled airspace below flight level 100 shall remain at least 1,500 metres horizontally and 1,000 feet vertically away from cloud and in a flight visibility of at least 5 km.

(3) Paragraph (2) shall not apply to an aircraft which:
(a) flies at or below 3,000 feet above mean sea level;
(b) remains clear of cloud with the surface in sight; and
(c) is in a flight visibility of at least 5 km.

(4) Paragraph (2) shall not apply to an aircraft which is not a helicopter and which:
(a) flies at or below 3,000 feet above mean sea level;
(b) flies at a speed which, according to its air speed indicator, is 140 knots or less;
(c) remains clear of cloud with the surface in sight; and
(d) is in a flight visibility of at least 1,500 metres.

(5) Paragraph (2) shall not apply to a helicopter which:
(a) flies at or below 3,000 feet above mean sea level;
(b) flies at a speed which, having regard to the visibility, is reasonable;
(c) remains clear of cloud with the surface in sight; and
(d) is in a flight visibility of at least 1,500 metres.

(6) Paragraphs (1) and (2) shall not apply to a helicopter which is air-taxiing or conducting manoeuvres in accordance with rule 6(i).


Additionally, the restrictions on the holder of a PPL(A) without IMC or IR prohibit operating in conditions below 3km visibility outside CAS.

So far, so good. If we're operating below 3000 ft AMSL then 1500m is the limiting visibility for an aeroplane pilot if they hold IMCR or IR.

However, Rule 33 defines IFR (Rule 34 is not relevant to below 3000ft AMSL).

33 (1) Subject to paragraphs (2) and (3), an aircraft shall not fly at a height of less than 1,000 feet above the highest obstacle within a distance of 5 nautical miles of the aircraft unless:
(a) it is necessary for the aircraft to do so in order to take off or land;
(b) the aircraft flies on a route notified for the purposes of this rule;
(c) the aircraft has been otherwise authorised by the competent authority in relation to the area over which the aircraft is flying; or
(d) the aircraft flies at an altitude not exceeding 3,000 feet above mean sea level and remains clear of cloud and with the surface in sight and in a flight visibility of at least 800 metres.

(2) The aircraft shall comply with rule 5.

(3) Paragraph (1) shall not apply to a helicopter that is air-taxiing or conducting manoeuvres in accordance with rule 6(i).

So we are compliant with para (1) if sub-paras (a), (b) and (c) apply, or if sub-para (d) applies.

So my question is this: does this mean that if flying COCISS (day or night) with an IR or IMCR, we can elect to fly IFR below 1000ft above the highest obstacle within 5nm if the visibility is 800m or more? i.e. if flying by night, is it possible to fly iaw Rule 5 (500 ft rule) and ignore the 1000ft above obstacles within 5nm rule, provided that the pilot holds an IR / IMCR and the visibility is above 800m? Would this permit visual take-offs and landings at night from airfields without SIDs or IAPs in conditions of visibility above 800m but less than 1500m? If not, can someone please explain why?

I'm asking as the answer has relevance to a report I have to look at and comment on, not because I'm advocating flying at 500ft at night without NVG in 800m vis!

Many thanks,

SBW

[sarboy w****r]

Would it help if I phrased the question to be "what do you consider to be the lowest permitted in-flight visibility for night flight below 1000ft when not following an instrument approach procedure"?

Thanks,

[selfin]

'COCISS' is clear of cloud and in sight of the surface? The "in sight of the surface" was changed a few years ago to "with the surface in sight."

Apart from the contrary common sense aspect there doesn't appear to be a prohibition on operating at heights less than 1000 ft above obstacles located within 5 nm of the aircraft subject to the stated conditions (IFR, in flight visibility not less than 800 m, outside controlled airspace, private or aerial work flight, pilot in command holds the appropriate qualifications, etc).

In spite of that, the common sense aspect is given some enforceability under Articles 86 (Pre-flight action by commander of aircraft other than EU-OPS aeroplanes), 87 (Commander to be satisfied that flight can be safely completed) and 109 (Aerial work and private aircraft – aerodrome operating minima) of the Air Navigation Order 2009.

[selfin]

SBW,

Minor comment on your remark,

So we are compliant with para (1) if sub-paras (a), (b) and (c) apply, or if sub-para (d) applies.

The list should be read as (a) or (b) or (c) or (d), although any combination may also be satisfied (if practicable).

[sarboy w****r]

Thanks selfin, I had been wondering about how the conditions should be interpreted and whether I'd been misreading them.

However, if it were (a) or (b) or (c) or (d) then this implies that it is legal to descend below 1000ft above obstacles within 5nm when making an approach or when taking off, irrespective of the weather conditions or whether or not you are following a recognised IAP, i.e. this then allows anyone to make an approach of any sort that they have just made up... Is this really what is intended here?

[selfin]

That's addressed by Art. 109 of the ANO.

Article 109

(8) A flight must not be continued towards the aerodrome of intended landing unless the latest available information indicates that conditions at that aerodrome, or at least one alternate aerodrome, will, at the estimated time of arrival, be at or above the specified aerodrome operating minima.

(9) In this article:

(a) 'specified' in relation to aerodrome operating minima means such detailed information about aerodrome operating minima as have been notified for the aerodrome or, if the relevant minima have not been notified, such minima as are ascertainable by reference to the notified method for calculating aerodrome operating minima; and

(b) 'designated' in relation to an instrument approach procedure means notified, prescribed or otherwise designated by the relevant competent authority.


See also 109(5).

[sarboy w****r]

Thanks selfin, that's very helpful.

What happens if the pilot goes to an unlicensed aerodrome for which there are no published IAPs and for which there are no published operating minima, what is the means by which the aerodrome operating minima are calculated? i.e. such minima as are ascertainable by reference to the notified method for calculating aerodrome operating minima

[selfin]

No idea what material the UK CAA publishes on establishing AOM. OzExpat might know - see http://www.pprune.org/questions/395653-how-calculate-aerodrome-operating-minima-oca-h.html

ICAO doc 9365 offers some guidance. For an understanding of what goes into developing IAPs look at ICAO PANS-OPS (doc 8168).

[sarboy w****r]

Thanks very much!