Aerodromes - Visual Aids, Markings and Signs — Page 405, Lesson 556

Let’s pick up with the signs on the aerodrome. We’ve already covered the markings on the runway and taxiway surfaces, so now we move to the vertical signs that sit alongside them. These signs are governed by a general specification, and I want to walk you through it carefully because it sets the rules for everything else. First, the purpose. Signs are provided on aerodromes to do three things: convey a mandatory instruction, give information on a specific location or destination on the movement area, or provide other information as required. So a sign is either telling you something you must do, telling you where you are or where you’re going, or giving you some other necessary information. Now the physical characteristics. Signs shall be frangible. That means they’re designed to break away easily on impact, so if an aircraft or vehicle hits one, it doesn’t cause serious damage. And those located near a runway or taxiway shall be sufficiently low to preserve clearance for propellers and the engine pods of jet aircraft. So height is controlled to keep them clear of the spinning propellers and the engine nacelles hanging under the wings. Shape matters too. Signs shall be rectangular, with the longer side horizontal. So they’re landscape-oriented rectangles, not squares and not vertical. Here’s a key colour rule: the only signs on the movement area utilizing red shall be mandatory instruction signs. Red is reserved exclusively for signs that give a mandatory instruction. Nothing else on the movement area gets to use red. Another rule: signs showing numbers only refer to runways. So if you see a sign with just a number, it’s identifying a runway, not a taxiway or anything else. For night use, signs shall be reflective and/or illuminated when intended for use at night. And they shall be illuminated when intended for use in three specific situations. First, in runway visual range conditions less than a value of 800 m. Second, at night in association with instrument runways. Third, at night in association with non-instrument runways where the code number is 3 or 4. So the illumination requirement kicks in for low visibility, for instrument runways at night, and for the larger non-instrument runways at night. Now let’s get into the mandatory instruction signs themselves. A mandatory instruction sign is provided to identify the location beyond which an aircraft taxiing or a vehicle shall not proceed unless authorized by the aerodrome control tower. So it marks a boundary you cannot cross without permission from the tower. The mandatory instruction signs include several types: runway designation signs, category I, II and III holding position signs, taxi-holding position signs, road-holding position signs, and NO ENTRY signs. So the family of mandatory signs covers runway identification, the various holding positions, and the no-entry prohibition. Now here’s the link back to the markings we covered earlier. A pattern “A” taxi-holding position marking shall be supplemented at a taxiway/runway intersection or a runway/taxiway intersection with a runway designation sign. So where you have that pattern A marking on the ground, you add a runway designation sign to tell you which runway you’re holding short of. A pattern “B” taxi-holding position marking shall be supplemented with a category I, II or III holding position sign. So pattern B gets the category holding position sign instead. And finally, a runway designation sign at a taxiway/runway intersection should be — and the text cuts off there, but that’s where the excerpt ends. So we’ve covered the general specification, the characteristics, and the mandatory instruction signs, plus how they pair with the pattern A and pattern B markings. Let me show you what these look like on the ground. shows the runway holding markings pattern A, and shows pattern B. Those are the markings that get supplemented with the signs we just discussed. That’s the core of the sign specification