# What does the letter G mean in a runway identifier?

Boulder Municipal Airport (KBDU) has runways 8 / 26 and also runways 8G / 26G. What is the significance of the letter G following the runway numbers?

• Possible duplicate of How are runways numbered? – GdD May 17 '18 at 7:33
• @GdD I don't agree on the duplicate, there is no mention of any "G" in that linked question/answers. – Federico May 17 '18 at 9:05
• @GdD ok, missed it. I'm evaluating editing to make it a bit more prominent, now it is really buried and hidden. – Federico May 17 '18 at 9:09
• @GdD one paragraph in the 4th answer hardly makes it a dupe. SE is supposed to make it easy to find the right answer, not a puzzle. – Notts90 May 17 '18 at 13:30
• For completeness' sake: This looks like a US-ism. As counterexamples, my Swedish airport directory lists for example Karlskoga ESKK with a 1499 x 30 m asphalt runway and a 900 x 40 m grass runway, both designated 03/21; or Gävle ESSK with a 2000 x 45 m asphalt runway and a 730 x 30 m grass runway, both 18/36. Not even any R/L designators with either of these; just two different, parallell runways with different surface characteristics and the same designations. – a CVn May 17 '18 at 17:17

For runways with other than hard surfaces it is common to list the runways with a letter G for grass or in the case of a seaplane base, with W for water.

An example of this is runway 8G at Boulder (KBDU) and runway 35W at David Wayne Hooks (KDWH).

You can see this information in the Chart Supplement pages and diagrams for each airport.

• Such as 21W in Manhattan. Once, USAir served it. – Harper May 18 '18 at 5:34
• This answer is not technically correct, the surface type of the runway is not indicated in the designation. It is a coincidence that "W" type runways are water, the suffix indicates type of runway not surface type. S = STOL runway, G = glider runway, W = water sealane or waterway, and U = ultralight runway. I would have commented sooner but I needed to build up some reputation, so I made my own answer. – PlaneGuy May 18 '18 at 21:16
• For a moment, when reading this, I thought you cited a suffix that meant that the runway had boulders. Took me a moment to realize my mistake, but it did lead me to think up some really amusing airports before I realized it! – Cort Ammon May 19 '18 at 4:24
• @Harper I suspect they quickly realized that it would be difficult to turn a profit on that particular one. Also, I imagine the landing fees were kind of stiff in the end. – a CVn May 19 '18 at 8:13

The "G" suffix refers to a Glider runway.

The following verbiage is used in Advisory Circular: AC No: 150/5200-35 Page 15 RUNWAY IDENT

"The following suffixes can be used in conjunction with runway identification numbers even if the runway is not painted accordingly: S = STOL runway, G = glider runway, W = water sealane or waterway, and U = ultralight runway"

Interestingly runway 8G / 26G is actually a dual surface runway with part of it being paved and the remainder grass.

The following is the description of that runway: Found here AirNav: KBDU

Runway 8G/26G Dimensions: 4100 x 20 ft. / 1250 x 6 m
Surface: asphalt/turf, in fair condition
RWY 08G/26G 3,000X20 FT CHIP AND SEAL ON WEST END; EAST 1,100 FT IS GRASS.