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Runway Markings  
User currently offlineC5LOAD From United States of America, joined Sep 2008, 917 posts, RR: 0
Posted (5 years 1 month 2 weeks 21 hours ago) and read 11943 times:

I know this thread title has been used before, but I couldn't find my answer. Why do some runways have several white arrows leading to the piano keys? PLanes can use this area for takeoff too, so why wouldn't they just make the piano keys start back at the beginning instead of having 1500 ft. of white arrow leading to the piano keys?


"But this airplane has 4 engines, it's an entirely different kind of flying! Altogether"
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User currently offline2H4 From United States of America, joined Oct 2004, 8955 posts, RR: 60
Reply 1, posted (5 years 1 month 2 weeks 21 hours ago) and read 11947 times:
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Displaced thresholds typically exist for obstacle/terrain clearance on final. Another consideration is the load-bearing capability of that concrete or pavement. Runways are reinforced to withstand the weight of a landing aircraft, but not all displaced thresholds are.

2H4



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User currently offlineInnocuousFox From United States of America, joined Dec 2003, 2805 posts, RR: 14
Reply 2, posted (5 years 1 month 1 week 6 days 18 hours ago) and read 11740 times:



Quoting 2H4 (Reply 1):
Runways are reinforced to withstand the weight of a landing aircraft, but not all displaced thresholds are.

Which is actually the reverse order in effect. They don't bother to reinforce the extension area because they know that no one will be landing there... because of the clearance issue you mentioned.



Dave Mark - Intrinsic Algorithm - Reducing the world to mathematical equations!
User currently offlineMir From United States of America, joined Jan 2004, 21571 posts, RR: 55
Reply 3, posted (5 years 1 month 1 week 6 days 18 hours ago) and read 11718 times:



Quoting C5LOAD (Thread starter):
Why do some runways have several white arrows leading to the piano keys? PLanes can use this area for takeoff too

But they can't use it for landing. Thus the white arrows instead of the normal piano keys.

-Mir



7 billion, one nation, imagination...it's a beautiful day
User currently offline2H4 From United States of America, joined Oct 2004, 8955 posts, RR: 60
Reply 4, posted (5 years 1 month 1 week 6 days 15 hours ago) and read 11674 times:
AIRLINERS.NET CREW
DATABASE EDITOR



Quoting InnocuousFox (Reply 2):
They don't bother to reinforce the extension area because they know that no one will be landing there...

KLM is doing their darndest to convince them otherwise, though:


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Photo © JAR Photography



2H4



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User currently offlineEcuadorianMD11 From , joined Dec 1969, posts, RR:
Reply 5, posted (5 years 1 month 1 week 6 days 15 hours ago) and read 11653 times:

Do they use paint, or is it a coating of some kind?
"Slippery when wet?"

I believe that runway marking rules differ between different continents, correct?

Just trying to cover the basics here, please correct me if I´m wrong:

The barcode means start / end of runway, which can be followed by an (overshoot) area, normally not to be used. Then there´s a white line which indicates the middle of the runway, the number is the rough direction of the runway (minus 1 zero) rounded up to 10 degrees and a big cross on the runway would mean "runway not in use"!

Terrible to think about what happened to SQ in Taipei.............

Cheers,

Ecuadorian MD11.


User currently offlineInnocuousFox From United States of America, joined Dec 2003, 2805 posts, RR: 14
Reply 6, posted (5 years 1 month 1 week 6 days 15 hours ago) and read 11657 times:



Quoting EcuadorianMD11 (Reply 5):
I believe that runway marking rules differ between different continents, correct?

Gotta love Wikipedia



Dave Mark - Intrinsic Algorithm - Reducing the world to mathematical equations!
User currently offlineMir From United States of America, joined Jan 2004, 21571 posts, RR: 55
Reply 7, posted (5 years 1 month 1 week 6 days 14 hours ago) and read 11623 times:



Quoting EcuadorianMD11 (Reply 5):
I believe that runway marking rules differ between different continents, correct?

Yes, but not much. Some differences I can think of:

- In the US, they won't paint the first number if it's a zero (runway 9, for instance). The same runway in Europe would be painted 09 (and referred to as 'runway zero-nine' in ATC communications)
- The UK has a slightly different 1,000 foot marker than the US.
- Runways in Norway have yellow markings as opposed to white (probably to make visibility easier when there is snow on the runways)

All of them are minor, of course - there is pretty much an international standard.

-Mir



7 billion, one nation, imagination...it's a beautiful day
User currently offlineVikkyvik From United States of America, joined Jul 2003, 9949 posts, RR: 26
Reply 8, posted (5 years 1 month 1 week 6 days 13 hours ago) and read 11614 times:
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Quoting Mir (Reply 7):
- The UK has a slightly different 1,000 foot marker than the US.

...and most of the rest of the world  Smile

Also to be noted: the aiming point (the large solid white bar that Mir is talking about) is at 1000 feet in the US. In many other countries, it's somewhere between 1000 and 1500 feet (typically at a metric distance from the threshold, I think...seem to recall seeing 400 meters on several runways).

The rest of the touchdown zone markings also differ somewhat in different countries, although they're always typically located at 500 ft/150 meter increments.

Additionally, the US has historically used 8 large white bars for the threshold marking, while the rest of the world uses the standard 4, 6, 8, 12, or 16 bars (for 50, 75, 100, 150, and 200 foot wide runways respectively). Most new-construction or repainted runways in the US now use this format as well.



"Two and a Half Men" was filmed in front of a live ostrich.
User currently offlineEcuadorianMD11 From , joined Dec 1969, posts, RR:
Reply 9, posted (5 years 1 month 1 week 6 days 11 hours ago) and read 11588 times:



Quoting InnocuousFox (Reply 6):
Gotta love Wikipedia

Point taken, point taken........
But I think a lot of people post questions here because of the nice personal answers at times and the discussion it may ignite afterwards.
Wikipedia is clinically good & accurate..........I learn more at Airliners.net however!
Mir & Vikkyvik for instance.........
Good link by the way, thanks! Good drawings.........

Quoting Mir (Reply 7):
In the US, they won't paint the first number if it's a zero

Interesting, any idea why? Saving paint? Is it really paint, or some other coating?

Further more, the aiming point is about 350 meters (roughly 1000 feet) down the runway? Really, interesting! I mean I knew that they don´t use the 1st meters like they do on aircraft carriers............but skipping 350 meters seems quite a lot! I don´t think they skip that much at UIO / GYE where I live, but that´s maybe because of short runways to start off with.

Cheers,

Ecuadorian MD11


User currently offlineVikkyvik From United States of America, joined Jul 2003, 9949 posts, RR: 26
Reply 10, posted (5 years 1 month 1 week 6 days 11 hours ago) and read 11577 times:
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Quoting EcuadorianMD11 (Reply 9):
Further more, the aiming point is about 350 meters (roughly 1000 feet) down the runway? Really, interesting! I mean I knew that they don´t use the 1st meters like they do on aircraft carriers............but skipping 350 meters seems quite a lot! I don´t think they skip that much at UIO / GYE where I live, but that´s maybe because of short runways to start off with.

Well, a typical 3-degree approach has the aircraft crossing the threshold at a height of 50 feet. At a 3-degree descent (meaning little to no flare), the airplane will touch down just about 950 feet down the runway.

This allows a margin of error on both sides of the touchdown point. If your landing point is right at the threshold, and you land short, you could be in deep trouble  Smile

Also, 1000 feet is better estimated as 300 meters than 350 (it's actually about 305 meters).



"Two and a Half Men" was filmed in front of a live ostrich.
User currently offlineInnocuousFox From United States of America, joined Dec 2003, 2805 posts, RR: 14
Reply 11, posted (5 years 1 month 1 week 6 days 10 hours ago) and read 11563 times:



Quoting EcuadorianMD11 (Reply 9):
Quoting InnocuousFox (Reply 6):
Gotta love Wikipedia

Point taken, point taken........
But I think a lot of people post questions here because of the nice personal answers at times and the discussion it may ignite afterwards.

I think you missed my intent entirely. I was looking there for my own benefit on a few things. I found that it answered some of the questions here, so I simply posted it for others.



Dave Mark - Intrinsic Algorithm - Reducing the world to mathematical equations!
User currently offlineFaro From Egypt, joined Aug 2007, 1542 posts, RR: 0
Reply 12, posted (5 years 1 month 1 week 5 days 23 hours ago) and read 11475 times:



Quoting 2H4 (Reply 1):
Displaced thresholds typically exist for obstacle/terrain clearance on final. Another consideration is the load-bearing capability of that concrete or pavement. Runways are reinforced to withstand the weight of a landing aircraft, but not all displaced thresholds are.

I may be mistaken, but I believe a departing aircraft at MTOW exerts a greater load on the runway pavement than a landing aircraft at MLW and nominal flare.

Faro



The chalice not my son
User currently offline2H4 From United States of America, joined Oct 2004, 8955 posts, RR: 60
Reply 13, posted (5 years 1 month 1 week 5 days 21 hours ago) and read 11439 times:
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DATABASE EDITOR



Quoting Faro (Reply 12):
I may be mistaken, but I believe a departing aircraft at MTOW exerts a greater load on the runway pavement than a landing aircraft at MLW and nominal flare.

I'm not sure about that, either. But wouldn't they have to plan (and build) for landing impacts above and beyond that of a normal flare? We wouldn't want a hard landing to damage the runway, after all.

So if a normal flare/landing is X g's, I wonder how much of a margin must be built into runway surfaces. X + 10%? 20%? It would be interesting to learn.

2H4



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User currently offlineFaro From Egypt, joined Aug 2007, 1542 posts, RR: 0
Reply 14, posted (5 years 1 month 1 week 5 days 21 hours ago) and read 11432 times:



Quoting 2H4 (Reply 13):
So if a normal flare/landing is X g's, I wonder how much of a margin must be built into runway surfaces. X + 10%? 20%? It would be interesting to learn.

It would indeed, given also that one would perhaps incorporate another additional margin into the displaced threshold pavement area: pilots sometimes undershoot as is graphically demonstrated by your 747 pix in SXM above. I have a sneaking suspicion that the displaced threshold is built to the same load bearing standards as the nominal landing area...

Faro



The chalice not my son
User currently offlineFredT From United Kingdom, joined Feb 2002, 2185 posts, RR: 26
Reply 15, posted (5 years 1 month 1 week 5 days 20 hours ago) and read 11414 times:



Quoting EcuadorianMD11 (Reply 9):
Wikipedia is clinically good & accurate.

I'd be very, very cautious with that assumption if I was you! Wikipedia is very often way, way off.

The source to be trusted on runway markings is ICAO Annex XIV. Member states who wish to deviate from this should include this in their list of exceptions.



I thought I was doing good trying to avoid those airport hotels... and look at me now.
User currently offlineMSNDC9 From , joined Dec 1969, posts, RR:
Reply 16, posted (5 years 1 month 1 week 5 days 19 hours ago) and read 11387 times:

Quoting EcuadorianMD11 (Reply 5):
Do they use paint, or is it a coating of some kind?
"Slippery when wet?"

They use reflective beads in the paint at most airports.

FAA Standards are here:

http://www.faa.gov/airports/resource.../media/150-5340-1J/150_5340_1j.pdf

[Edited 2009-07-21 09:40:15]

User currently offlineMir From United States of America, joined Jan 2004, 21571 posts, RR: 55
Reply 17, posted (5 years 1 month 1 week 5 days 16 hours ago) and read 11338 times:



Quoting EcuadorianMD11 (Reply 9):
Interesting, any idea why?

Because that's the way the runway is referred to. What would be "runway zero-nine" in other countries is just "runway nine" in the US.

I suspect, though, that your real question is why the runways are referred to that way in the US. And unfortunately, I can't be of any help there - I have no idea.

-Mir



7 billion, one nation, imagination...it's a beautiful day
User currently offlineVikkyvik From United States of America, joined Jul 2003, 9949 posts, RR: 26
Reply 18, posted (5 years 1 month 1 week 5 days 16 hours ago) and read 11333 times:
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Quoting Faro (Reply 12):
I may be mistaken, but I believe a departing aircraft at MTOW exerts a greater load on the runway pavement than a landing aircraft at MLW and nominal flare.

At nominal flare, maybe. But as 2H4 stated, they have to allow for hard landings and such.

To calculate some (very) rough numbers for a 737-800 (data taken from Boeing's website):

MTOW: 174,200 lbs
MLW: 146,300 lbs

At a forward approach speed of 150 mph (220 ft/s), and 3 degree glideslope, vertical speed will be around 690 ft/min (11.5 ft/s). Assume that the flare arrests the vertical speed to 300 ft/min (5 ft/s) (I have no idea how good this approximation is for flare). Assume that it takes one second for the vertical speed to be arrested upon contact with the ground.

Based on those simple numbers (and not knowing much about airplane shock absorbers), it'll take about 22,715 lbs of force to arrest the airplane's descent. Add that to the max landing weight, and you get 169,015 lbs of force.

That obviously discounts any lift the wings may still be producing, though the spoilers will do a good job of cutting that down.

Say the aircraft lands hard, assuming no flare at all, and keeping everything else the same, it'll take about 52,245 lbs of force to arrest the descent. Add MLW and you get 198,545 lbs - significantly more than MTOW.

Again, these are extremely simplified approximations done mostly for my own interest  Smile



"Two and a Half Men" was filmed in front of a live ostrich.
User currently offlineTb727 From United States of America, joined Jun 2005, 1588 posts, RR: 9
Reply 19, posted (5 years 1 month 1 week 5 days 15 hours ago) and read 11322 times:



Quoting MSNDC9 (Reply 16):
They use reflective beads in the paint at most airports.

And the paint is slippery when wet, especially if there is a coating of snow you can really tell if you hit a paint line if you have some brake pressure being applied.



Too lazy to work, too scared to steal!
User currently onlineStarlionblue From Greenland, joined Feb 2004, 17030 posts, RR: 67
Reply 20, posted (5 years 1 month 1 week 5 days 11 hours ago) and read 11272 times:



Quoting EcuadorianMD11 (Reply 5):
The barcode means start / end of runway,

I seem to recall that only runways over a certain length have piano keys. Is this correct?



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offline2H4 From United States of America, joined Oct 2004, 8955 posts, RR: 60
Reply 21, posted (5 years 1 month 1 week 5 days 11 hours ago) and read 11272 times:
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Quoting Starlionblue (Reply 20):
I seem to recall that only runways over a certain length have piano keys. Is this correct?

Upon reading this, my mind inexplicably went to this photo:


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Photo © Julian Adams



2H4



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User currently offlineMir From United States of America, joined Jan 2004, 21571 posts, RR: 55
Reply 22, posted (5 years 1 month 1 week 5 days 1 hour ago) and read 11186 times:



Quoting 2H4 (Reply 21):
Upon reading this, my mind inexplicably went to this photo:

My question would be: why even bother?

-Mir



7 billion, one nation, imagination...it's a beautiful day
User currently offlineLeej From United Kingdom, joined Apr 2001, 293 posts, RR: 0
Reply 23, posted (5 years 1 month 1 week 5 days ago) and read 11172 times:

Got me thinking now (must be lunchtime!)
If an aircraft is at MLW, does it mean that it lands with that full weight thumping down, or is it much less because of course the aircraft is still generating lift at the point of touchdown? The aircraft is still in effect flying when the tyres smoke, with the weight bearing down slowly (to it's gross weight) once all lift has been cancelled. This would verify Faro's belief that an aircraft at MTOW would indeed place more stress on the pavement during the initial take-off roll.
Just a thought....


User currently offlineMir From United States of America, joined Jan 2004, 21571 posts, RR: 55
Reply 24, posted (5 years 1 month 1 week 4 days 18 hours ago) and read 11119 times:



Quoting Leej (Reply 23):
Got me thinking now (must be lunchtime!)
If an aircraft is at MLW, does it mean that it lands with that full weight thumping down, or is it much less because of course the aircraft is still generating lift at the point of touchdown? The aircraft is still in effect flying when the tyres smoke, with the weight bearing down slowly (to it's gross weight) once all lift has been cancelled. This would verify Faro's belief that an aircraft at MTOW would indeed place more stress on the pavement during the initial take-off roll.
Just a thought....

But all the lift is cancelled out pretty quickly due to the spoilers coming out. And on takeoff, the wings do start generating lift and taking some weight off the wheels before the nose actually lifts off. So it works both ways.

-Mir



7 billion, one nation, imagination...it's a beautiful day
25 Post contains images DanVS : I don't have any numbers, but I believe it's more or less like you said. In many airports, the ends of the runways are paved in concrete (more resist
26 Post contains images Scooter01 : So that you can go back and remember... We've got something like tthis at FBU too... (Not my pic., but one done by P.A. Viking at Scanair Forum .no)
27 Leej : Sorry I am still not convinced. If one looks at the A330 videos at MAN on Youtube, where touchdowns are so graceful - is it correct that the complete
28 Vikkyvik : Oooo, that's a tough one.... I've definitely seen runways as short as 4000-odd feet with piano keys.... Gonna have to try and research that. Not all
29 2H4 : I don't think anyone is arguing that this is the case. I think the discussion (at least at first) suggested that a hard landing can drive the mains i
30 DanVS : I've found a description of ICAO recommended airport signs and runway markings. It's on the introduction section of an old set of Jeppesen charts I b
31 Faro : I imagine runways are stressed to greater loads than MTOW or MLW aircraft landing at very high rates of descent: conceivably you should also accommod
32 Swiftski : The start of the runway is actually at the holding point. You then have TODA, TORA, LDA, etc Centreline In some cases, an airport with 020/200 will u
33 EcuadorianMD11 : Thanks, you´re right! I put that wrong...........I meant "centre" as in longtitudonal..........so for instance: at 2000 meters on a 4000 meter runwa
34 Vikkyvik : You mean, the holding point on a taxiway? Not saying you're wrong, but wouldn't that be described as the runway environment or runway clear area or s
35 Swiftski : If you pass the holding point, then you are "on the runway" even if you have not turned onto it. If you pass a holidng point without clearance, it is
36 EcuadorianMD11 : I guess you meant 50 yards............ Now a different question, though slightly off topic: could big jets (A380-330-40 / B777-747) land on semi-pave
37 Starlionblue : I don't think they "should" land on a semi-paved runway. I mean in an emergency anything should be tried, but it probably isn't good either for the pl
38 Vikkyvik : Not to mention, airplanes have even sunk into asphalt when they taxied onto a taxiway they weren't supposed to....I think there are photos in the dat
39 EcuadorianMD11 : Interesting...........and what does a gravel kit consist of please? I´m imagining: higher ground clearance / some kind of protection behind the land
40 Post contains images Starlionblue : Higher ground clearance: No Protection behind landing gear: Yes. A skid on the front. The front gear doors are altered to allow more space. This lead
41 FredT : But is the 'start of the runway' the same as 'the point where you enter the runway'? I'd say no, or things would be getting interesting. Stick with '
42 HAWK21M : Any Examples? regds MEL...
43 FredT : The King Air 200 is one type I know of which has high flotation gear available as a retrofit.
44 Tdscanuck : It's not the same. You're supposed to include an allowance for the distance you use between entering the runway and starting the takeoff roll. The In
45 Post contains images 2H4 : Here are some fun ones: 2H4
46 EcuadorianMD11 : Interesting pics..........that skid is amazing.......no diversion to an asphalt runway though, I suppose!! What ´s that vortex thingy for exactly? I
47 Starlionblue : Oh it works fine on an asphalt/concrete runway. The wheels actually extend a bit below the skid. As I understand it (and I could be wrong), it disrup
48 Post contains images 2H4 : Allow me 2H4
49 Starlionblue : Thanks. I knew I could count on you!
50 A389 : At the end of the runway the published TORAs are the 'black top' length and generally no allowance is made for line up distance. Effectively the TORA
51 Post contains images EcuadorianMD11 : Slightly off topic, although not so much. The pic down here shows you the runway we use at our local airfield. As basic as it gets, as you can see: Ho
52 Rwessel : Runways exist that are sloped, have bumps or dips, and even have modest bends in them. OTOH, the flatter the better, for the most part, but if you ke
53 EcuadorianMD11 : I suppose........but I reckoned that that is kind of high maintenance keeping it up to scratch. My idea was to do it properly once and be done with i
54 Starlionblue : There are runways with quite sharp bends in the middle. I'm sure 2H4 has some interesting pics.
55 Post contains links and images Vikkyvik : Not to steal 2H4's thunder or anything, but it was simply too easy to find (remembered it was in Denmark) View Large View MediumPhoto © SilverWi
56 EcuadorianMD11 : Bring ´m on! Please.......... How the h#ll does that work??? A sharp bend during take off and / or landing?? Ecuadorian MD11.
57 Starlionblue : Well, you just turn. There were runways in Laos and Vietnam during the Vietnam war that were really really gnarly.
58 EcuadorianMD11 : Hey, I didn´t see that pic when I posted my last reply! Good stuff.......... Looks like the driving range of a golf course! Well, I prefer a take of
59 Rwessel : Well, grass you have to mow once or twice a week, you might need to water it depending on your area (easily taken care of by a set of collapsible spr
60 Post contains links Vikkyvik : So, after a complete and utter lack of research, I stumbled upon an interesting runway today. My cousin just went skydiving for the first time this p
61 FredT : You can roll on one wheel prior to achieving enough speed to lift off, thereby banking the aircraft and providing the lateral force required to track
62 Brandi747 : Interesting, any idea why? Saving paint? Is it really paint, or some other coating? In the US military runways will have the Zero before the single di
63 Post contains links and images 2H4 : Well, there's Elk City, Idaho: Some great photos can be seen here Then there's Dixie Town, Idaho. "The 3,000 foot runway is 80 feet wide but it also
64 MSNDC9 : Those are because of runway extensions of an existing asphalt runway, not because of the strength of the pavement. A relatively large percentage of o
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