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    AC 150/5370-10F (Item P620 Runway and Taxiway Painting) has been modified, replacing the previous version, 10E. Despite previously recommending brighter glass beads (either Type III or Type IV) to make holding position environments more visible to pilots, the FAA has eliminated the use of hi-index Type III glass beads in red and pink paints. The FAA has elected to now recommend the use of low-index, Type I or Type IV, glass beads on red and pink paint at reduced application rates.

    When painting red or pink backgrounds typically found in surface painted holding position markings (SPHPM) and geographic position markings (GPM), the standard glass bead coverage rates are both reduced by 2 pounds/gallon. Meaning, Type I beads are applied at 5 pounds/gallon and Type IV beads are applied at 6 pounds/gallon in these cases.

    Many airports have painted the SPHPM signs without glass beads for various reasons. One is that during darkness, the white inscriptions are easier to see. However, on GPM signs, the inscriptions are black. If the pink background is not reflective enough (many are not already), the black inscription will lose contrast during darkness.

    This change is a disservice to marking systems because:

  1. All markings in the holding position environment should be highly visible.
  2. GPM signs are part of the Surface Movement Guidance Control System (SMGCS), which is employed under low visibility conditions. Therefore, the signs should be highly visible.
  3. A solid matrix of glass beads in the paint extends the life of the coating.
  4. SPHPM signs will no longer "mimic" the vertical lighted signs during darkness because the red will practically be invisible.
  5. Read more on this subject in our article, "Sign Language".

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