bbcmeng
Topic Author
Posts: 10
Joined: Sat Jun 13, 2015 4:43 am

Runway slope difference

Tue Jul 10, 2018 3:53 pm

Since we all know the world is not perfectly flat, runways, even though they often look flat, are not either. Most runways vary in altitude and slope from one end to the other. So it has got me thinking:

For runways with a large difference, are pilots aware of this when landing?

Other than Tenzing-Hillary in Nepal, are there other busier runways with a difference in altitude that could make operations a little more challenging?

Also, are there any airports that are completely below sea level? Or any that are split between above and below sea level?

Thanks.
 
FriscoHeavy
Posts: 1255
Joined: Tue May 27, 2014 4:31 pm

Re: Runway slope difference

Tue Jul 10, 2018 4:01 pm

AMS is -11 ft below sea level.

What do you consider a large difference from one end to the other?
Whatever
 
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TOGA10
Posts: 184
Joined: Thu Dec 01, 2016 8:49 am

Re: Runway slope difference

Tue Jul 10, 2018 4:02 pm

bbcmeng wrote:
Since we all know the world is not perfectly flat, runways, even though they often look flat, are not either. Most runways vary in altitude and slope from one end to the other. So it has got me thinking:

For runways with a large difference, are pilots aware of this when landing?

Other than Tenzing-Hillary in Nepal, are there other busier runways with a difference in altitude that could make operations a little more challenging?

Also, are there any airports that are completely below sea level? Or any that are split between above and below sea level?

Thanks.

One that comes to mind straight away is Bristol in the U.K. . Definitely noticeable in the flare! 12ft difference in elevation between the threshold at 09 and 27.
And yes, Amsterdam is below sea level!
The natural function of the wing is to soar upwards and carry that which is heavy up to the place where dwells the race of gods. More than any other thing that pertains to the body it partakes of the nature of the divine. - Plato
 
Chaostheory
Posts: 1070
Joined: Wed Mar 06, 2013 2:09 am

Re: Runway slope difference

Tue Jul 10, 2018 4:13 pm

bbcmeng wrote:
Since we all know the world is not perfectly flat, runways, even though they often look flat, are not either. Most runways vary in altitude and slope from one end to the other. So it has got me thinking:

For runways with a large difference, are pilots aware of this when landing?

Other than Tenzing-Hillary in Nepal, are there other busier runways with a difference in altitude that could make operations a little more challenging?

Also, are there any airports that are completely below sea level? Or any that are split between above and below sea level?

Thanks.


Airport charts will contain the runway elevation and the gradient of significant slopes.

The runway slopes at most major airports don't pose much of an issue in and of themselves. It's the undulating runways or the ones with humps that you've got to be wary of. Eg We fly into Manchester which has a pronounced hump on 23R. I always draw attention to it during the briefing if the pf fails to mention it.
 
bbcmeng
Topic Author
Posts: 10
Joined: Sat Jun 13, 2015 4:43 am

Re: Runway slope difference

Tue Jul 10, 2018 4:22 pm

FriscoHeavy wrote:
AMS is -11 ft below sea level.

What do you consider a large difference from one end to the other?



I would think more than 30-40 feet would be a large difference.
 
kalvado
Posts: 891
Joined: Wed Mar 01, 2006 4:29 am

Re: Runway slope difference

Tue Jul 10, 2018 5:27 pm

bbcmeng wrote:
FriscoHeavy wrote:
AMS is -11 ft below sea level.

What do you consider a large difference from one end to the other?



I would think more than 30-40 feet would be a large difference.

Whatever it worth: runway gradients are given in 0.1% increments. That is 7 feet for 7000' (2100m) runway.
And some numbers are relatively high - KLAS has 0.9-1.1% gradient and 100' elevation difference between runway ends.
Talk about 18.6% zt Courchevel for real slope..
 
SuseJ772
Posts: 758
Joined: Wed Aug 10, 2005 11:13 am

Re: Runway slope difference

Tue Jul 10, 2018 5:35 pm

What I never understood is why do major runways have any slope at all? It isn’t that hard to grade and level, especially with GPS equipment in graders. I get that little airports might not have the sophistication or desire to spend the money, but why wouldn’t a ATL have 0 slope?
Currently at PIE, requesting FWA >> >>
 
SuseJ772
Posts: 758
Joined: Wed Aug 10, 2005 11:13 am

Re: Runway slope difference

Tue Jul 10, 2018 5:35 pm

What I never understood is why do major runways have any slope at all? It isn’t that hard to grade and level, especially with GPS equipment in graders. I get that little airports might not have the sophistication or desire to spend the money, but why wouldn’t a ATL have 0 slope?
Currently at PIE, requesting FWA >> >>
 
FriscoHeavy
Posts: 1255
Joined: Tue May 27, 2014 4:31 pm

Re: Runway slope difference

Tue Jul 10, 2018 5:47 pm

bbcmeng wrote:
FriscoHeavy wrote:
AMS is -11 ft below sea level.

What do you consider a large difference from one end to the other?



I would think more than 30-40 feet would be a large difference.



As someone else mentioned, some can have pretty big discrepancies. LAS for example, has a 146 ft difference in elevation between 8L/26R.
Whatever
 
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flyPIT
Posts: 1112
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Re: Runway slope difference

Tue Jul 10, 2018 5:55 pm

SuseJ772 wrote:
What I never understood is why do major runways have any slope at all? It isn’t that hard to grade and level, especially with GPS equipment in graders. I get that little airports might not have the sophistication or desire to spend the money, but why wouldn’t a ATL have 0 slope?


Slopes are accounted for in the flight's performance calculations. In the case of a minor slope I imagine it is cheaper to add a few feet to the runway's length to make up for any lost performance as opposed to building a completely level runway.

In the case of ATL, I believe they built a slope on 26L/R in order to keep a factory (Ford?) located near the end of the runway. Ironically looking at Google Earth the factory has recently been removed.
FLYi
 
timz
Posts: 6425
Joined: Fri Sep 17, 1999 7:43 am

Re: Runway slope difference

Tue Jul 10, 2018 6:52 pm

If you're on a 3-degree descent to a runway with a 1% slope, it will look quite different from the same runway in the other direction.
 
GalaxyFlyer
Posts: 1139
Joined: Fri Jan 01, 2016 4:44 am

Re: Runway slope difference

Tue Jul 10, 2018 6:53 pm

Slopes of +/-2% is the maximum for most FAR 25 certifications. Greater slopes would require an engineering analysis and, perhaps, flight test.

GF
 
JayinKitsap
Posts: 796
Joined: Sat Nov 26, 2005 9:55 am

Re: Runway slope difference

Wed Jul 11, 2018 4:40 am

2% of a 10,000 ft runway is 200 feet, about a 16 story building in height. Trying to hold level would mean massive earth moving efforts. A 1% of slope makes drainage easier, the normal crown of a road is 2%.

SEA's third runway finally opened to traffic on November 20, 2008, as an Alaska Airlines flight took off for Denver following a dedication ceremony. The completed runway is a vast strip of concrete 8,500 feet long, 150 feet wide, and 17 inches deep. To make it level with the other two runways, it sits on a plateau built up with 500,000 truckloads of fill dirt held in place by a 1,430-foot-long, 130-foot-high retaining wall.


It was only $1.1 billion.
 
KAUSpilot
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Joined: Mon Jan 28, 2002 2:15 pm

Re: Runway slope difference

Wed Jul 11, 2018 5:45 am

Luxembourg airport and Campinas/Veracopas Brazil (VCP) are the only ones that come to mind. They both have a hump near the touchdown zone on one end that will make for very hard landings if not expected. Most airliners I've flown have a limitation that runway slope not exceed +/- 2% of runway length.
 
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exFWAOONW
Posts: 547
Joined: Wed Nov 25, 2009 10:32 pm

Re: Runway slope difference

Mon Jul 23, 2018 3:05 pm

To really complicate things, long runways need a dip in the middle to make it easier for the pilot to see the other end, especially on hot days. But that is only practical in flat territory. Otherwise, to minimize earth moving, they typically follow the lay of the land up to a point.
Is just me, or is flying not as much fun anymore?
 
26point2
Posts: 1000
Joined: Wed Mar 03, 2010 6:01 am

Re: Runway slope difference

Tue Jul 24, 2018 12:20 pm

There are various ways to determine a runway’s slope...not a big deal. What I don’t like is the runway that undulates. This is not noted anywhere I’ve seen. Airport diagram might illustrate a “flat” runway but while on short final it’becomes clear that there is a substantial dip or two along its length. KBNA 02C/20C for example.
 
HAWKXP
Posts: 62
Joined: Tue Aug 19, 2014 6:03 am

Re: Runway slope difference

Sat Jul 28, 2018 7:02 pm

There are level runways?? (learned to fly in the Colorado mountains)
 
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PatrickZ80
Posts: 2631
Joined: Tue Jul 13, 2010 5:33 am

Re: Runway slope difference

Sat Jul 28, 2018 7:36 pm

HAWKXP wrote:
There are level runways?? (learned to fly in the Colorado mountains)


Yes, there are. For example here in the Netherlands, where the land is as flat as a mirror. Not even the slightest bump. Most of this land was once the bottom of the sea, but it has been reclaimed. I'm living in this flat land a few meters below sealevel, and so are the airports around here.

When I grew up as a child, mountains were something special. Something we didn't have at home and you could only see while on holiday far away. Now that I'm older they're not so special anymore, I've seen plenty, but still I feel at home in this land where they don't exist. Rather amazing that there are people on this planet who can't imagine flat land, which for me has always been something natural.
 
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RRTrent
Posts: 431
Joined: Sat Aug 29, 2015 8:12 am

Re: Runway slope difference

Tue Jul 31, 2018 10:03 am

18 posts in and no-one's mentioned the 3 humps at BHX.. standards are slipping guys :P

https://www.youtube.com/watch?v=l6EC3JPwTmM
 
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TOGA10
Posts: 184
Joined: Thu Dec 01, 2016 8:49 am

Re: Runway slope difference

Tue Jul 31, 2018 12:02 pm

26point2 wrote:
There are various ways to determine a runway’s slope...not a big deal. What I don’t like is the runway that undulates. This is not noted anywhere I’ve seen. Airport diagram might illustrate a “flat” runway but while on short final it’becomes clear that there is a substantial dip or two along its length. KBNA 02C/20C for example.

Both DBV and SPU are notorious for having such a runaway, with the added joys of surrounding terrain..
The natural function of the wing is to soar upwards and carry that which is heavy up to the place where dwells the race of gods. More than any other thing that pertains to the body it partakes of the nature of the divine. - Plato

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