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I've noticed that on runways at Canadian airports, runway numbers are painted noticeably smaller than runway numbers at airports pretty much anywhere else. For instance, here's the beginning of runway 32 at Ottawa Airport in Canada, and here's the beginning of runway 32 at Buffalo Airport in New York. Or the beginning of runway 32 (left) at Madrid airport in Spain.

Does anyone know why the runway numbers are printed smaller? Wouldn't it be best for them to be nice and large so as to be readable from the air?

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  • $\begingroup$ After reading @ymb1 answer, it is strange that FAA (among other) didn't adopt ICAO size, but doesn't declare the deviation in the US AIP. The deviation from §5.2.2.6 in Annex 14 of Chicago Convention should be mentioned the way it is done for, e.g. §5.2.2.4: "Zeros are not used to precede single digit runway markings" (see page GEN 1.7-86 of the AIP). $\endgroup$ – mins Feb 8 '17 at 19:07
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    $\begingroup$ @mins That's odd. I could swear I've seen "09" painted on US runways. Am I nuts or did they change at some point? $\endgroup$ – TomMcW Feb 8 '17 at 21:19
  • $\begingroup$ @TomMcW: It was already mentioned in 2009 AIP. I can't find older versions. $\endgroup$ – mins Feb 9 '17 at 9:43
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(Click either to view)

Short answer: Canada paints them by the book. They're not small.

Ottawa airport conforms to the standards set by ICAO Annex 14 for airport design. Those standards guarantee the legibility of the numbers.

5.2.2.6 The numbers and letters shall be in the form and proportion shown in Figure 5-3. The dimensions shall be not less than those shown in Figure 5-3, but where the numbers are incorporated in the threshold marking, larger dimensions shall be used in order to fill adequately the gap between the stripes of the threshold marking.

Member states can deviate and then notify ICAO they have deviated, as long as the height of the characters does not go below 9 meters (30 feet).

There's no answer to why they are smaller than the rest, checking how +250 countries paint the numbers to compare with Canada is unattainable. Canada and many others (Crete, Athens, Cairo, Lisbon, ...) paint them like that, and that's the norm per ICAO.

enter image description here
Measurement from Google Earth for Ottawa.

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    $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$ – Farhan Feb 9 '17 at 18:49

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