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: 1163
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
 
User avatar
TOGA10
Posts: 170
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: 1065
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: 855
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: 739
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: 739
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: 1163
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
 
User avatar
flyPIT
Posts: 961
Joined: Wed Jun 15, 2016 6:21 am

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: 6392
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: 862
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: 758
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
Posts: 1679
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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