Upslope/downslope RWY
Thread Starter
Joined: Mar 1999
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From: UK
Upslope/downslope RWY
Please help solve a dilemma we're having at the moment!
There is a lot of controversy as to whether the tendency is to approach a downsloping runway too high or too low. Logic would dictate that you tend to approach too high, but sources at the CAA say that, for the JAR ATPL exams, the correct answer to the question would be a tendency to approach too low.
I figure that some here would be able to shed light on this...
(jointly posted with a poll on Professional Pilot Training to hear the views from those currently studying for ATPLs)
There is a lot of controversy as to whether the tendency is to approach a downsloping runway too high or too low. Logic would dictate that you tend to approach too high, but sources at the CAA say that, for the JAR ATPL exams, the correct answer to the question would be a tendency to approach too low.
I figure that some here would be able to shed light on this...
(jointly posted with a poll on Professional Pilot Training to hear the views from those currently studying for ATPLs)
Joined: Jun 2000
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From: Geriatrica, UK
A slightly more rigorous definition of "downsloping" might be helpful to avoid misunderstandings.
Does "downsloping" mean sloping down away from the touch-down area or the other way around?
If the RW slopes down away from the touch-down, then it must be true that a pilot looking for the usual sight-picture on the approach would position himself on a steeper than normal approach angle.
Whether or not this is "too" high is a value judgement. It might be perfectly acceptable but just not "normal".
Does "downsloping" mean sloping down away from the touch-down area or the other way around?
If the RW slopes down away from the touch-down, then it must be true that a pilot looking for the usual sight-picture on the approach would position himself on a steeper than normal approach angle.
Whether or not this is "too" high is a value judgement. It might be perfectly acceptable but just not "normal".
Joined: Jul 2003
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From: An Island Province
I quote from FLIGHT SAFETY AUSTRALIA, SEPTEMBER-OCTOBER 2002 page 17 – 'whoose plane is it anyway' - diagrams are in the magazine. Beware of the ambiguity in the downslope description.
Pilots may incorrectly perceive they are too high if:
The runway is narrower than usual.
The runway is longer than usual.
The runway slopes up from the threshold.
The terrain slopes up to the threshold.
The approach is flown over featureless terrain including water and unlit ground.
Visibility is significantly better than usual.
The runway and approach lights are brighter than usual.
Pilots may incorrectly perceive they are too low if:
The runway slopes down from the threshold.
The runway is wider or shorter than usual.
The runway and approach lights are dimmer than usual.
Visibility is poor.
Pilots may incorrectly perceive they are too high if:
The runway is narrower than usual.
The runway is longer than usual.
The runway slopes up from the threshold.
The terrain slopes up to the threshold.
The approach is flown over featureless terrain including water and unlit ground.
Visibility is significantly better than usual.
The runway and approach lights are brighter than usual.
Pilots may incorrectly perceive they are too low if:
The runway slopes down from the threshold.
The runway is wider or shorter than usual.
The runway and approach lights are dimmer than usual.
Visibility is poor.
Joined: Mar 2000
Posts: 8,571
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From: Arizona USA
The publication described above is more or less correct, and is in agreement from FAA sources.
Great care needs to be taken when approaching an upsloping runway.
Many years ago was dispatched (with a Fairchild FH227B) to a dirt runway at Cabo San Lucus, BahaSur, Mexico (quite a well known resort now, with a rather large paved runway) and the upslope was 7%...just a tad steep.
Land up hill, takeoff down hill was the procedure.
A very preculiar optical illusion, especially at dusk with flare pots for lighting.
Marlin was tasty tho....
Great care needs to be taken when approaching an upsloping runway.
Many years ago was dispatched (with a Fairchild FH227B) to a dirt runway at Cabo San Lucus, BahaSur, Mexico (quite a well known resort now, with a rather large paved runway) and the upslope was 7%...just a tad steep.
Land up hill, takeoff down hill was the procedure.
A very preculiar optical illusion, especially at dusk with flare pots for lighting.
Marlin was tasty tho....
Joined: Dec 2002
Posts: 2,776
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From: UK
411A Is your ‘more or less’ a slightly ‘upslope’ runway or slightly ‘down slope’ runway; or alternatively is it that the rest of the world is more or less in line with the FAA?
Whilst my psychologist acquaintances may agree that most things are more or less; my physiologist friends confirm that when approaching an up-sloping runway (touchdown point lower than the remaining runway) pilots have the illusion that they are too high, thus fly a below optimum glide slope approach. The opposite is true for a down-slope runway.
Neither friends nor acquaintances have comment on your down slope take off, but from experience there is the danger that after take off with continuing down sloping ground there is inappropriate feeling of having excess altitude, this is fine until the next upslope.
Whilst my psychologist acquaintances may agree that most things are more or less; my physiologist friends confirm that when approaching an up-sloping runway (touchdown point lower than the remaining runway) pilots have the illusion that they are too high, thus fly a below optimum glide slope approach. The opposite is true for a down-slope runway.
Neither friends nor acquaintances have comment on your down slope take off, but from experience there is the danger that after take off with continuing down sloping ground there is inappropriate feeling of having excess altitude, this is fine until the next upslope.
Joined: Mar 2000
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From: Arizona USA
safetypee,
Upslope runway, ie; approaching a runway where the threshold is lower than the far end.
This particular runway was on the immediate coastline and perpendicular thereto. The only viable approach was from the water, landing uphill.
No obsticles on takeoff, at the end of the runway was the beach.
This particular airport was a public facility, but unattended normally.
Transportation was there for our pax (and crew), but otherwise, no one else...or so I thought.
Out of the weeds walked a perfectly dressed governmental official, wanting the overflight and landing fees...cash please.
Upslope runway, ie; approaching a runway where the threshold is lower than the far end.
This particular runway was on the immediate coastline and perpendicular thereto. The only viable approach was from the water, landing uphill.
No obsticles on takeoff, at the end of the runway was the beach.
This particular airport was a public facility, but unattended normally.
Transportation was there for our pax (and crew), but otherwise, no one else...or so I thought.
Out of the weeds walked a perfectly dressed governmental official, wanting the overflight and landing fees...cash please.
Joined: Dec 2003
Posts: 8
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From: USA
Upslope/downslope RWY
Never been there but it sounds like some of the places I go in and out of. I also do line checks on thease routes and a little trick I use when I want to see if they can stay on the profile is to have the tower turn off the vasi and you whould no beleave how many will go low on the down slope and high on the up slope. Just my 2ct's worth.
Safe flying.
Safe flying.
Joined: Sep 2003
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From: Amidst the polar bears
"the correct answer to the question would be a tendency to approach too low."
I think part of the problem here might be the word "tendency". As I see it (and we all seem to understand the problem, just not the answer) if I was on the desired glideslope (PAPI/ILS/etc) and I knew it to be a downsloping runway (as in down and away from the TD point) then I would anticipate feeling as if I was low on the visual GP and would ensure to position my self accordingly at the transition. If, however, I was making a strictly visual approach to the same runway with little forethought as to the slope then my tendency would be to establish myself high on the desired glidepath in order to accomodate the visual clues.
Have I sufficiently straddled the fence for everyone?
I think part of the problem here might be the word "tendency". As I see it (and we all seem to understand the problem, just not the answer) if I was on the desired glideslope (PAPI/ILS/etc) and I knew it to be a downsloping runway (as in down and away from the TD point) then I would anticipate feeling as if I was low on the visual GP and would ensure to position my self accordingly at the transition. If, however, I was making a strictly visual approach to the same runway with little forethought as to the slope then my tendency would be to establish myself high on the desired glidepath in order to accomodate the visual clues.
Have I sufficiently straddled the fence for everyone?
