Underwing registration

[pup150]

I just wanted to get opinions of the height something like a C172 / PA28 would be for the underwing reg to be clearly read by the naked eye .

The reason I ask is On Sunday afternoon an aircraft (2 to 4 seat single engine) circled the village I live in a few miles south of Northampton around a dozen times annoying the neighbours with the noise. I wasn't there at the time so didn't witness it and find it a bit odd that they would purposely overfly that many times. The under wing registration was clearly seen with the naked eye by someone with slightly less than average sight (albeit written down incorrectly, so no calls to the CAA).

[Kolibear]

ISTR than the size of the letters is such that they can be read up to 1500'. So the rule of thumb is that if you can read them, the a/c is a tad low.

[Circuit Basher]

Chapter and verse on marking of registrations is contained in Schedule 2 to Part B of CAP 393 (Air Nav Order) (http://www.caa.co.uk/docs/33/CAP393.PDF) - this starts on Page 138 of the document.
Nationality and registration marks of aircraft registered in the United Kingdom
1 General
(1) The nationality mark of the aircraft shall be the capital letter ‘G’ in Roman character and the registration mark shall be a group of four capital letters in Roman character assigned by the CAA on the registration of the aircraft. The letters shall be without ornamentation and a hyphen shall be placed between the nationality mark and the registration mark.
(2) The nationality and registration marks shall be displayed to the best advantage, taking into consideration the constructional features of the aircraft and shall always be kept clean and visible.
(3) The letters constituting each group of marks shall be of equal height and they, and the hyphen, shall all be of the same single colour which shall clearly contrast with the background on which they appear.
(4) The nationality and registration marks shall also be inscribed on a fire-proof metal plate affixed in a prominent position:
(a) in the case of a microlight aeroplane, either in accordance with sub-paragraph (c) or on the wing;
(b) in the case of a balloon, on the basket or envelope; or
(c) in the case of any other aircraft on the fuselage or car as the case may be.
(5) The nationality and registration marks shall be painted on the aircraft or shall be affixed thereto by any other means ensuring a similar degree of permanence in the manner specified in paragraphs 2 and 3 of this Part.
2 Position and size of marks
(1) The position and size of marks on heavier than air aircraft (excluding kites) shall be as follows:
(a) on the horizontal surfaces of the wings:
(i) on aircraft having a fixed wing surface, the marks shall appear on the lower surface of the wing structure and shall be on the port wing unless they extend across the whole surface of both wings. So far as is possible the marks shall be located equidistant from the leading and trailing edges of the wings. The tops of the letters shall be towards the leading edge of the wing;
(ii) the height of the letters shall be:
(aa) subject to sub-paragraph (bb), at least 50 centimetres;
(bb) if the wings are not large enough for the marks to be 50 centimetres in height, marks of the greatest height practicable in the circumstances;
(b) on the fuselage (or equivalent structure) and vertical tail surfaces:
(i) the marks shall also appear either:
(aa) on each side of the fuselage (or equivalent structure), and shall, in the case of fixed wing aircraft be located between the wings and the horizontal tail surface; or
(bb) on the vertical tail surfaces;
(ii) when located on a single vertical tail surface, the marks shall appear on both sides. When located on multi-vertical tail surfaces, the marks shall appear on the outboard sides of the outer-surfaces. Subject to sub-paragraphs (iv) and (v), the height of the letters constituting each group of marks shall be at least 30 centimetres;
(iii) if one of the surfaces authorised for displaying the required marks is large enough for those marks to be 30 centimetres in height (whilst complying with subparagraph (v)) and the other is not, marks of 30 centimetres in height shall be placed on the largest authorised surface;
(iv) if neither authorised surface is large enough for marks of 30 centimetres in height (whilst complying with sub-paragraph (v)), marks of the greatest height practicable in the circumstances shall be displayed on the larger of the two authorised surfaces;
(v) the marks on the vertical tail surfaces shall be such as to leave a margin of at least 5 centimetres along each side of the vertical tail surface;
(vi) on rotary wing aircraft where owing to the structure of the aircraft the greatest height practicable for the marks on the side of the fuselage (or equivalent structure) is less than 30 centimetres, the marks shall also appear on the lower surface of the fuselage as close to the line of symmetry as is practicable and shall be placed with the tops of the letters towards the nose. The height of the letters constituting each group of marks shall be:
(aa) subject to sub-paragraph (bb), at least 50 centimetres; or
(bb) if the lower surface of the fuselage is not large enough for the marks to be of 50 centimetres in height, marks of the greatest height practicable in the circumstances;
(c) wherever in this paragraph marks of the greatest height practicable in the circumstances are required, that height shall be such as is consistent with compliance with paragraph 3 of this Part.
(2) The position and size of marks on airships and free balloons shall be as follows:
(a) in the case of airships the marks shall be placed on each side of the airship. They shall be placed horizontally either on the hull near the maximum cross-section of the airship or on the lower vertical stabiliser;
(b) in the case of free balloons, the marks shall be in two places on diametrically opposite sides of the balloon;
(c) in the case of both airships and free balloons the side marks shall be so placed as to be visible from the sides and from the ground. The height of the letters shall be at least 50 centimetres.
3 Width, spacing and thickness of marks
(1) For the purposes of this paragraph:
(a) ‘standard letter’ shall mean any letter other than the letters I, M and W;
(b) the width of each standard letter and the length of the hyphen between the nationality mark and the registration mark shall be two thirds of the height of a letter;
(c) the width of the letters M and W shall be neither less than two thirds of their height nor more than their height; and
(d) the width of the letter I shall be one sixth of the height of the letter.
(2) The thickness of the lines comprising each letter and hyphen shall be one sixth of the height of the letters forming the marks.
(3) Each letter and hyphen shall be separated from the letter or hyphen which it immediately precedes or follows, by a space equal to either one quarter or one half of the width of a standard letter. Each such space shall be equal to every other such
space within the marks.
It doesn't give any specific legibility information, but from personal experience, an aircraft directly overhead has to be no greater than around 1200ft overhead for me to stand any chance of reading the reg (and my uncorrected vision is marginal for the CAA medics - I just had to start wearing glasses for driving / flying).

[MLS-12D]

Can't speak for the UK, but in Canada "the display of marks on the bottom surface of the wings is optional" [ref: CARs para.222.01(1)(h)]. ;)

[LowNSlow]

As anybody who has seen Annie the Auster will testify you can read her registration from space :D

Seriously though, I thought the standard reg was designed to be read at 1,000' agl. Any comments from those in the know?

[TheKentishFledgling]

N reg a/c don't even need to show underwing reg marks...

tKF

[Fried_Chicken]

N reg a/c don't even need to show underwing reg marks...

Although the Das Air American reg'd Dc10s do carry their reg's under the wings.

The Germans also don't (usually) carry their reg's under the wing

Fried Chicken

[Paris Dakar]

I was taught that if the reg was clearly visible from the ground, and I wasn't on approach/climb out, then chances are you are flying too low.:sad:

PD

[Maude Charlee]

Sounds like it may have been an aerial photo company, as this is the usual modus operandi for the speculative end of the business. That should no doubt be confirmed in short order when a sales team descend on the houses in your area trying to flog exorbitantly expensive piccies of your village. Don't pay more than a couple of quid if you really want one.

Some of them are well run professional outfits, but there are also many cowboy outfits who regularly have run ins with the CAA for breaching the low flying regs.

However, it may also have been somebody locally on a pleasure flight who just wanted to see where they lived from the air.

Either way, unless the reg was absolutely crystal clear, and as you only live in a village, I doubt they were doing anything more than being a nuisance. They can quite legally circle your village down to 500' at which point you ought to be able to read the reg without great difficulty. It's a poor reflection on the pilot's consideration for the locals though, as even for aerial photography, there really isn't the need to be as low as 500' for shooting a village.

[MOREOIL]

I think you have to be 500 ft from house etc which means if the aircraft was 400 ft outside the village he would be legal at 300 ft above ground, however- the locals will swear he was no more than roof hieght and right over their garden ! being legal is not usually ehough, my experience is that people will say you were overhead if they raise an eyebrow to see you , rather than lay on the floor looking straight up. complainers have a very loose grip on the truth. i have been very precise about where i was and how high agl and have had angry nutters swear i was some lower ! the fact that i was 18 inches from the altimeter and they several kilometers from it does not seem to matter, fly low at your peril

[Flyin'Dutch']

The under wing registration was clearly seen with the naked eye by someone with slightly less than average sight (albeit written down incorrectly,...).

Can you re-read that statement and tell me how convincing that one is?

Height estimations of flying objects by people on the ground are notoriously inacurate.

The height at which an aeroplane registration can be read when it flies overhead will depend on the distance, size and type of letter used, background, light and visual acuity of the observer.

I like everyone to fly considerate without causing a nuisance as the latter would not do the GA case any good.

However for someone to claim that they have seen their place being circled so that they saw the registration 'clearly' a dozen or so times despite their less than brilliant eyesight, but then managed not to write it down correctly, does not seem to cut the mustard.

[ARLG]

I agree with FD. I visited Old Warden for their first shindig this year. For the 'guess the height' competition I suggested 50 foot, it was in fact over 200.

[Spitoon]

The ICAO Standards for registration marks re contained in Annex 73. LOCATION OF NATIONALITY, COMMON AND REGISTRATION MARKS
3.1 General
The nationality or common mark and registration mark shall be painted on the aircraft or shall be affixed by any other means ensuring a similar degree of permanence. The marks shall be kept clean and visible at all times.
3.3 Heavier-than-air aircraft
3.3.1 Wings. On heavier-than-air aircraft, the marks shall appear once on the lower surface of the wing structure. They shall be located on the left half of the lower surface of the wing structure unless they extend across the whole of the lower surface of the wing structure. So far as is possible, the marks shall be located equidistant from the leading and trailing edges of the wings. The tops of the letters and numbers shall be toward the leading edge of the wing.

4. MEASUREMENTS OF NATIONALITY, COMMON AND REGISTRATION MARKS
The letters and numbers in each separate group of marks shall be of equal height.
4.2 Heavier-than-air aircraft
4.2.1 Wings. The height of the marks on the wings of heavier-than-air aircraft shall be at least 50 centimetres.
4.2.2 Fuselage (or equivalent structure) and vertical tail surfaces. The height of the marks on the fuselage (or equivalent structure) and on the vertical tail surfaces of heavier-than-air aircraft shall be at least 30 centimetres.

5. TYPE OF CHARACTERS FOR NATIONALITY, COMMON AND REGISTRATION MARKS
5.1 The letters shall be capital letters in Roman characters without ornamentation. Numbers shall be Arabic numbers without ornamentation.
5.2 The width of each character (except the letter I and the number 1) and the length of hyphens shall be two-thirds of the height of a character.
5.3 The characters and hyphens shall be formed by solid lines and shall be of a colour contrasting clearly with the background. The thickness of the lines shall be one-sixth of the height of a character.
5.4 Each character shall be separated from that which it immediately precedes or follows, by a space of not less than one-quarter of a character width. A hyphen shall be regarded as a character for this purpose.No mention of why the marks have to be these particular sizes so I guess you'd need to ask an optician about the capabilities of the human eye and do a bit of geometry.

In practice there's lots of evidence that even those who are familiar with aircraft and the way they are operated have difficulty estimating the height of an aircraft overhead.

[pup150]

quote:
--------------------------------------------------------------------------------
The under wing registration was clearly seen with the naked eye by someone with slightly less than average sight (albeit written down incorrectly,...).
--------------------------------------------------------------------------------

Flyin Dutch, before you jump to conclusions, My wife read the registration , she wears glasses for driving, slightly short sighted, She was not wearing them at the time, was in the garden when our village and adjacent village was overflown around a dozen times lower than anything else she has witnessed there. We often get PFL's into fields nearby. A couple of hours later she wrote the reg down from memory to ask me when I got back if I knew it from our local field. She either mixed the letters up or a read a D as an O or something. When I looked it up on the CAA site it was clearly not the aircraft she saw.

I was merely interested to know if underwing registrations on the standard SEP types such as C172 or PA28 were a standard size and would be visible above 500ft to slightly less than average eyesight, that's all!

[Flyin'Dutch']

Pup,

Does this:
albeit written down incorrectly, so no calls to the CAA
and
When I looked it up on the CAA site it was clearly not the aircraft she saw
mean that if there would have been a PA28/C172 with the registration that your wife had written down (and we now know to be incorrect) you would have rung the CAA and thus caused distress and hassle to an unsuspecting pilot?

[pup150]

Flyin Dutch,

After calling the CAA I would have called the MOD to see why it hadn't been intercepted and escorted away for daring to spoil the Sunday afternoon silence in our quaint little village.

Maybe a smiley after the reference to the CAA in the original post would have confirmed I meant that in Jest.

Reason I looked it up was to see what it was and where it was from and yes I might have been tempted to ring the owners and only after confirming that aircraft overflew this area numerous times at that particular time of the day would have explained the effect their flying has had on some of the local population, politely of course!

Anything wrong with that, if you don't tell people they don't know? We have enough trouble in this country with noise complaints and particularly with the airfield I fly from!

The whole point of this post was to try and get an estimate of the maximun height the aircraft would have been for the reg to be visible. If you don't have anything to contribute to the original question which I think was a valid question judging by the number of informed replies then don't post!

[Flyin'Dutch']

P,

No need to get all hot and bothered, just 'cause I made some comments on your posting, thought that most Northamptonshire lads' shoulders would be broad enough to take that.

Think indeed that by making a reasonable point to anyone when complaint about noise achieves more than a rant. Lots of innocent folks find themselves under the looking glass after being 'shopped' by 'fellow' aviators that have particular axes to grind.

The point that I tried to make in my second post was that based upon an unreliable observation people may well have had the bother of a phone call, at best a polite one from you, at worst one from the CAA.

There were indeed no smilies in your posting so you will have to forgive me for taking the contents for what they read as.

To state that I made no contribution to your original posting is a bit unkind as I stated that there are lots of reasons why people may get a registration wrong, or whether the wing is on the top or the bottom of the craft.

Anyway I have looked for you at the Snellen chart and used my calculator. Dunno what your wife's uncorrected visual acuity is but for someone with 20/20 or 6/6 vision the answer is 333 meters.

;)

[pup150]

Flyin,

Thanks for your info.

I replied with haste in between working for a living and apologise.

[Flyin'Dutch']

Pup,

No worries, broad shire shoulders here.

Been known to be 'robust' myself.

;)