seilfly
12th Aug 2009, 07:07
(I am not a proffessional pilot yet so I will post this in this subforum)
The FAA Aeronautical Information Manual (AIM) describes two types of threshold markings but fails to inform when the different types will be used. The "configuration A" being 8 longitudal pianokeys and "config B" being longitudal pianokeys and the number of pianokeys being a code for the RWY-width...
How can I tell the difference between a config A (8 pianokeys) and config B on a 100ft wide RWY which also has 8 pianokeys?
When do they use config A vs config B?
Reference:
http://www.faa.gov/air_traffic/publications/ATpubs/AIM/Chap2/aim0203.html
- Part 2-3-3 Runway Markings, point h
- and table 2-3-2
- and figure 2-3-1
selfin
14th Aug 2009, 14:25
Refer to A.C. 150/5340-IJ (http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/0/8852E94E6586FDD28625700300509565?OpenDocument&Highlight=standards%20for%20airport%20markings) (current, 2005/04/29) and to 150/5340-1K (http://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/number/150_5340-1K) (draft, issued 2009/05/26).
Configuration A for Part 139 airports is being phased out. I'm not sure what stage the phasing out has reached but the work started a few years back. Only Configuration B is acceptable now and has been the case from the start of 2008 (A.C. 150/5340-1J, Sec. 1.9(d)). Configuration B runway threshold markings are the same as required under ICAO Annex 14 (Vol I). Refer to preamble to Draft AC 150/5340-1J (link below), Paras 3(f) and 3(u), together with Chapter 2, 2.5 at PDF page 10.
For an idea of what the FAA considers a standard runway width, refer to AC 150/5300-13 (p. 21)
The rule for Configuration A markings requires scaling the width of the stripes and their spacings (and the outboard spacings from the runway edges) proportionally, keeping the length fixed. For a runway 150 feet wide the Configuration A stripes are 12 ft wide with 3 ft spacings (and an 8 ft spacing from the inboard stripe to the centreline, leaving 10 ft between the outboard and runway edge). The Configuration B stripes are given a fixed width of 5.75 ft with spacings of 5.75 ft also. If a Configuration A scheme were used on a narrow runway such that the stripes were equal to the width of the Configuration B stripes, the runway width would need to be about 72 feet (12 ft stripe width for a 150 ft runway width scaled to 5.75 ft for 71.875 ft). For a 72 ft wide runway bearing the Configuration A scheme the spacing between stripes would be reduced to slightly less than 1.5 ft. The difference between the schemes therefore ought to be apparent.
Airport Engineering (Airport Safety and Standards) AAS-100 is the contact point for further information. See here (http://www.faa.gov/about/office_org/headquarters_offices/arp/offices/aas/aas100/).