Landing downwind
Chuck Mea
Had and interesting decision to make yesterday. I was landing on grass in
a 5 knot wind. The runway had a 3 or 4 degree slope. I had the choice of
landing
up slope with a 5 knot tail wind or down slope into the wind. I chose
the up slope and had no problem. Anyone have a rule of thumb here or
comments.
Chuck
John R. Johnson
It is a real judgement call, Chuck. It depends on the steepness of the
slope and the wind strength. The biggest problem have with a downhill
landing is landing. As you get closer to touchdown the runway keeps
descending away from you! It is real easy to fly over most of the
runway trying to catch it, and then be too slow for a go-around safely.
John
Don McCall
On 24 May 1996, Chuck Mea wrote:
> Had and interesting decision to make yesterday. I was landing on grass in
> a 5 knot wind. The runway had a 3 or 4 degree slope. I had the choice of
> landing
> up slope with a 5 knot tail wind or down slope into the wind. I chose
> the up slope and had no problem. Anyone have a rule of thumb here or
> comments.
My instructor told me, years ago, to always go for the uphill landing
if tailwind component is 10 knots or less (depends on the slope and
surface, of course). Seems to work fine, for a rule of thumb...
Don
Tim Long
In article <4o4r00$d...@newsbf02.news.aol.com>, chuc...@aol.com (Chuck
Mea) wrote:
> Had and interesting decision to make yesterday. I was landing on grass in
> a 5 knot wind. The runway had a 3 or 4 degree slope. I had the choice of
> landing
> up slope with a 5 knot tail wind or down slope into the wind. I chose
> the up slope and had no problem. Anyone have a rule of thumb here or
> comments.
> Chuck
Seems like I read an article analyzing this subject many years ago in
Flying or some such periodical. I recall the conclusion that in most
cases, it's better to go for the headwind/downslope rather than
downwind/upslope situation. This is because you touch down slower and you
can use brakes to slow you on the ground. Apparently that's more effective
than landing fast and letting the upslope assist in your deacceleration.
J. P. Rourke
tl...@mail.vcnet.com (Tim Long) wrote:
Read the previous reply, it seems to match my (limited) experience - a
3 to 4 degree downslope is _huge_! To compare, realize the standard
ILS glideslope is 3 degrees, at a 90-kph approach this results in
about 477 fpm descent. Even if your landing airspeed is 60 knots, a
3.5 degree downslope is like the ground falling away from you at the
rate of 370 ft/min (no wind) or 309 ft/min with a 10knot headwind.
How easy is it to attain 300 fpm down in ground effect, while trying
to reduce airspeed to stall speed? I don't know - I'll leave that to
more experienced folks here - but I wouldn't be surprised if it is
nearly impossible in some aircraft, especially really clean ones like
canards or sailplanes. ( The upslope helps you get on the ground
sooner, braking should be done with brakes, IMHO :).
And don't try to take off from a 1 degree upslope 2600-ft field of
6-inch grass in a fully loaded Cessna 152 on a hot August afternoon
with no wind 2 days after getting your PPL. It can be done, but I
don't recommend it!
And I know of a strip in rural Virginia that looked like an upslope of
30 degrees (it probably was 5 or so) - Land upslope, take-off
downslope, head/tail wind irrelevant, go around not bloody likely!
-jpr
-jpr
J. P. Rourke
j...@ix.netcom.com (J. P. Rourke) wrote:
....
>ILS glideslope is 3 degrees, at a 90-kph approach this results in
Oops, I meant 90 kts! A little different...
-jpr
Dennis
I started flying the hard way with hang gliders and ultralights and
will ALWAYS EVERY TIME land upslope downwind rather than downslope
and upwind. We used to land back on TOP (after takeoff into the wind)
at Crestline in CA with a 10-12 mph tailwind. Just remember FULL FLARE..
Downslope can float forever...
DA
Tim Long wrote:
...
paolo amodeo
I think it's always better to land with the wind in front,the wind was
not dangerous(5 kts).
Paolo
PatrickFlo
In article <4oavg8$k...@sjx-ixn5.ix.netcom.com>, j...@ix.netcom.com (J. P.
Rourke) writes:
>>In article <4o4r00$d...@newsbf02.news.aol.com>, chuc...@aol.com (Chuck
>>Mea) wrote:
>
>>> Had and interesting decision to make yesterday. I was landing on
grass in
>>> a 5 knot wind. The runway had a 3 or 4 degree slope. I had the
choice of
>>> landing
>>> up slope with a 5 knot tail wind or down slope into the wind. I
chose
>>> the up slope and had no problem. Anyone have a rule of thumb here or
>>> comments.
>>> Chuck
Also keep in mind, if you're flying a taildragger, you'll run out of
rudder authority in a hurry. Stay on the brakes. Landing a taildragger
with a quartering tailwind on hard surface or close cropped grass runway
is a sure recipe for a groundloop.
Patrick
John R. Johnson
On 26 May 1996, Tim Long wrote:
>
> Seems like I read an article analyzing this subject many years ago in
> Flying or some such periodical. I recall the conclusion that in most
> cases, it's better to go for the headwind/downslope rather than
> downwind/upslope situation. This is because you touch down slower and you
> can use brakes to slow you on the ground. Apparently that's more effective
> than landing fast and letting the upslope assist in your deacceleration.
>
You assume you can get on the ground to use those brakes, and that they
will be effective if you do. You do not have to roll very far uphill
to dissipate a LOT of energy. Once again, it depends on the slope and
on the wind speed. If the slope if more than a couple of degrees I
would go with uphill unless the wind were very strong. Then I might
go with "elsewhere!"
John
Clayton L. Cranor
Chuck Mea wrote:
>
> Had and interesting decision to make yesterday. I was landing on grass in
> a 5 knot wind. The runway had a 3 or 4 degree slope. I had the choice of
> landing
> up slope with a 5 knot tail wind or down slope into the wind. I chose
> the up slope and had no problem. Anyone have a rule of thumb here or
> comments.
> Chuck
Always land uphill. I can tell you that any wind strong enough for you to
consider a downhill landing on a steeply inclined strip will probably be
strong enough to land my cub vertically. This is not fun flying. I have one
strip that is quite pitched... I always land up hill on it, and have with up
to 10-12 kts wind blowing from behind. VERY SCARY.
BTW. Such a situation is not the best time to land with a tailwind the first
time.
Clay
Jerry Bransford
--
Jerry Bransford
PP-ASEL, KC6TAY, C.A.P.
The Zen hotdog... make me one with everything!
dgam...@nbnet.nb.ca wrote:
>
> > chuc...@aol.com (Chuck Mea) writes:
> > Had and interesting decision to make yesterday. I was landing on grass in
> > a 5 knot wind. The runway had a 3 or 4 degree slope. I had the choice of
> > landing
> > up slope with a 5 knot tail wind or down slope into the wind. I chose
> > the up slope and had no problem. Anyone have a rule of thumb here or
> > comments.
> > Chuck
> >
> >>>>
> My instructor told me NEVER to land downslope even with a strong headwind,
> --last guy tried with a Navaho, downslope into a 20+ kn headwind, stopped
> in the creek off (way off ) the end of the rny. :(
>
> ............Dave
I would sure as Hell take my chances and land 'into' the wind even on a
slight downslope. How many runways have much more than a slight
downslope anyway. No runways on the side of steep hills, are there?
Landing into the wind gives you a *much* lower ground speed, and you've
got much less chance of landing 'long'. With the above example, landing
into the wind vs landing against the wind give you a 40 knot slower
ground speed advantage! Makes sense to me anyway!
dgam...@nbnet.nb.ca
Tim Long
> tl...@mail.vcnet.com (Tim Long) wrote:
>
> >In article <4o4r00$d...@newsbf02.news.aol.com>, chuc...@aol.com (Chuck
> >Mea) wrote:
>
> >> Had and interesting decision to make yesterday. I was landing on grass in
> >> a 5 knot wind. The runway had a 3 or 4 degree slope. I had the choice of
> >> landing
> >> up slope with a 5 knot tail wind or down slope into the wind. I chose
> >> the up slope and had no problem. Anyone have a rule of thumb here or
> >> comments.
> >> Chuck
>
> >Seems like I read an article analyzing this subject many years ago in
> >Flying or some such periodical. I recall the conclusion that in most
> >cases, it's better to go for the headwind/downslope rather than
> >downwind/upslope situation. This is because you touch down slower and you
> >can use brakes to slow you on the ground. Apparently that's more effective
> >than landing fast and letting the upslope assist in your deacceleration.
>
> Read the previous reply, it seems to match my (limited) experience - a
> 3 to 4 degree downslope is _huge_! To compare, realize the standard
> ILS glideslope is 3 degrees, at a 90-kph approach this results in
> about 477 fpm descent. Even if your landing airspeed is 60 knots, a
> 3.5 degree downslope is like the ground falling away from you at the
> rate of 370 ft/min (no wind) or 309 ft/min with a 10knot headwind.
> How easy is it to attain 300 fpm down in ground effect, while trying
> to reduce airspeed to stall speed? I don't know - I'll leave that to
> more experienced folks here - but I wouldn't be surprised if it is
> nearly impossible in some aircraft, especially really clean ones like
> canards or sailplanes. ( The upslope helps you get on the ground
> sooner, braking should be done with brakes, IMHO :).
>
> And don't try to take off from a 1 degree upslope 2600-ft field of
> 6-inch grass in a fully loaded Cessna 152 on a hot August afternoon
> with no wind 2 days after getting your PPL. It can be done, but I
> don't recommend it!
>
> And I know of a strip in rural Virginia that looked like an upslope of
> 30 degrees (it probably was 5 or so) - Land upslope, take-off
> downslope, head/tail wind irrelevant, go around not bloody likely!
I'll bet that the slope of the runway is measured in percent, not degrees.
A 3% downslope is 3 ft/100 ft linear. NOT nearly as much as 3 degrees.
John R. Johnson
On Wed, 29 May 1996, Jerry Bransford wrote:
> --
> Jerry Bransford
< < snip > >
>
> I would sure as Hell take my chances and land 'into' the wind even on a
> slight downslope. How many runways have much more than a slight
> downslope anyway. No runways on the side of steep hills, are there?
> Landing into the wind gives you a *much* lower ground speed, and you've
> got much less chance of landing 'long'. With the above example, landing
> into the wind vs landing against the wind give you a 40 knot slower
> ground speed advantage! Makes sense to me anyway!
>
Jerry, I don't know where you fly. I have seen MANY runways with a slope
greater than 4 or 5 degrees. This means you would have to descend at over
500 fpm just to keep from gaining altitude relative to the runway! The
ground speed advantage disappears REAL fast when you can't get down to
the ground. I have tried it both ways, and frequently had to go around
on downhill landings. I have flown into many sloped airports where there
IS NO going around. See the back country Idaho airport directory. You
will find many airports where ALL landing are made UPHILL and all takeoffs
downhill REGARDLESS of wind.
John
R Wood
This thread is a great example of the difference between the old
saying, "A pound of crop is worth a ton of theory."
I think you'll notice a big difference between the folks that have a
theory and the ones that have done it. How about hearing from those
that land in the conditions described on a regular basis?
Rhea Wood
N3489Y C-185
Alaska-Based Floatplane
Jerry Bransford
I see your point, John. And no, I haven't seen that many runways that
sloped very much, so I'm not experienced on steeply sloped runways. I
guess I've been lucky so far. They sound a little scary now!
Rod Farlee
Jerry Bransford wrote:
> I would sure as Hell take my chances and land 'into' the wind even on a
> slight downslope. How many runways have much more than a slight
> downslope anyway. No runways on the side of steep hills, are there?
Yes! There are steep (3-4%) runways, on hillsides, ridges, valley floors,
and mesas all over the west. Even a few in the east. Even a few really
steep ones (one in Idaho is 10%, a veritable ski-jump).
Please be very careful, and reconsider upwind/downhill landings before
going to any mountain airstrips. J. P. Rourke's posting in this thread
was very well thought out. Not only the runway, but also the surrounding
terrain, need to be carefully considered. Both factors generally favor
landing uphill.
Often, steep runways are in steep terrain, which keeps going up. An
attempt to land downhill into the wind will require a steep approach in
a strong updraft. I have sat in a 172 with full flaps with power off
going UP 400 fpm in short final. Being dumb (and inexperienced at the
time), I went around, came in REAL low brushing the treetops, and used
full flaps and a full slip to force it down to the runway. Even so,
landed long. Tried to brake on the 2% downhill slope on gravel and just
barely got it stopped. On a 4000' long runway into a 15 kt wind!
Taxied back, took off, landed uphill/downwind and used about half of it.
In other words, uphill/downwind was MUCH easier and safer. Partly because
the uphill approach was unobstructed.
I hestitate to make a general prescription, as every airport differs.
But for myself, I've found that whenever the runway slope is enough to
make me wonder, I've been much better off landing uphill.
To other low-time pilots: don't take any "sure as hell" advice, such as
"always land into the wind" or "always land uphill". Keep looking and
thinking (and always keep the option open to go somewhere else!)
- Rod Farlee
Jeffrey M. Matthews
During most of my glider towing days, downwind uphill landings were the
norm. That way we could let it roll right up to the next glider, make
a U turn, taxi forward 200 feet, and launch downhill and into the wind.
The downwind landings were ridiculously easy. The touchdown point was
so easy to judge that we had to constantly remind ourselves to move the
aiming point around to avoid wearing a hole in the grass. I have no
idea what the brake life was, since I don't recall replacing any. We'd
just tap a brake to make the turn.
The hills weren't all that steep. One runway lost, or gained, about 30
feet in the middle 1000 feet, the other had a 200 foot difference in
4000 feet. That works out to about 2 degrees. For steeper slopes, down-
wind uphill landings would be even more desirable.
When the wind got brisk, over 15 mph or so, we'd often land downhill and
into the wind, especially out west, where the ground was pretty rough,
to take it easier on the gear. But even then the downwind landing was
easier to judge.
Jeff Matthews
dgam...@nbnet.nb.ca
> Jerry Bransford <jer...@cts.com> writes:
> --
> Jerry Bransford
> PP-ASEL, KC6TAY, C.A.P.
> The Zen hotdog... make me one with everything!
> > > a 5 knot wind. The runway had a 3 or 4 degree slope. I had the choice of
> > > landing
> > > up slope with a 5 knot tail wind or down slope into the wind. I chose
> > > the up slope and had no problem. Anyone have a rule of thumb here or
> > > comments.
> > > Chuck
> > >
> > >>>>
> > My instructor told me NEVER to land downslope even with a strong headwind,
> > --last guy tried with a Navaho, downslope into a 20+ kn headwind, stopped
> > in the creek off (way off ) the end of the rny. :(
> >
> > ............Dave
>
> slight downslope. How many runways have much more than a slight
> downslope anyway. No runways on the side of steep hills, are there?
> got much less chance of landing 'long'. With the above example, landing
> into the wind vs landing against the wind give you a 40 knot slower
> ground speed advantage! Makes sense to me anyway!
>
>>>>
info is he had +20 kn headwind, - it is grass, 3500 ft long. - had a 172 on it
one day - 1700 rpm to taxi uphill.....................
Dave
Dave Farley
Jerry Bransford <jer...@cts.com> wrote:
> How many runways have much more than a slight
>downslope anyway. No runways on the side of steep hills, are there?
I know this isn't what you meant, but if you ever go skiing in Europe
I'd recommend that you take a look at Courcheval airport. It is
situated on the side of a mountain about half way up with 2-3000m
peaks all around. The first third of the runway is flat, the middle
third is at an angle of more than 30 degrees and the last third is
flat again.
------------
/
/
--------
You land at the base (and you'd better be accurate, because I doubt
that you could go around in an F15 let alone your average GA single)
and then hit the ramp which slows you down so much that you have to
power up to get onto the top. There's a very nice (but rather
expensive) bar alongside where you can watch the aircraft coming and
going whilst dining on lobster and strawberries ;-)
Take-off is the reverse, using the down-slope to gain enough speed
before you shoot out over the drop at the end of the runway ;-)
It's one of the places I really hope to fly into (not literally I
hope) myself someday just for the buz.
-------------------------------------------------
Dave Farley
SSA Object Technology Ltd.
-------------------------------------------------
Michael Bywater
In article <31b43084...@news.demon.co.uk>, da...@iosltd.demon.co.uk
(Dave Farley) wrote:
>downslope anyway. No runways on the side of steep hills, are there?
>
> I know this isn't what you meant, but if you ever go skiing in Europe
> I'd recommend that you take a look at Courcheval airport. It is
> situated on the side of a mountain about half way up with 2-3000m
> peaks all around. The first third of the runway is flat, the middle
> third is at an angle of more than 30 degrees and the last third is
> flat again.
>
> ------------
> /
> /
> --------
>
> You land at the base (and you'd better be accurate, because I doubt
> that you could go around in an F15 let alone your average GA single)
> and then hit the ramp which slows you down so much that you have to
> power up to get onto the top. There's a very nice (but rather
> expensive) bar alongside where you can watch the aircraft coming and
> going whilst dining on lobster and strawberries ;-)
>
> Take-off is the reverse, using the down-slope to gain enough speed
> before you shoot out over the drop at the end of the runway ;-)
>
> It's one of the places I really hope to fly into (not literally I
> hope) myself someday just for the buz.
I really, REALLY recommend it. Did it earlier this year in a PA32-300 and
a Mousquetaire (coming back from Meribel round the hill).
Great fun. And Mont Blanc is only 20 mins flying away to the north - going
round that at 2500 feet below the summit is quite an experience.
You need to get a mountain licence for Courchevel. They run a course in
the summer, although someone from Meribel flying club would train you in
the winter - better, because you get to play with ski undercarriage as
well.
--
Michael
John T. Lowry
In article <tlong-29059...@port50.vcnet.com>,
tl...@mail.vcnet.com says...
>
>In article <4oavg8$k...@sjx-ixn5.ix.netcom.com>, j...@ix.netcom.com (J.
P.
>Rourke) wrote:
>
>> tl...@mail.vcnet.com (Tim Long) wrote:
>>
>> >In article <4o4r00$d...@newsbf02.news.aol.com>, chuc...@aol.com
(Chuck
>> >Mea) wrote:
>>
on grass in
>> >> a 5 knot wind. The runway had a 3 or 4 degree slope. I had the
choice of
>> >> landing
>> >> up slope with a 5 knot tail wind or down slope into the wind.
I chose
>> >> the up slope and had no problem. Anyone have a rule of thumb
here or
>> >> comments.
>> >> Chuck
>>
>>
An average force derivation gives the following formula for
the "breakeven headwind," i.e., the headwind of such speed that it's a
wash whether you take off into the headwind up hill or take off with
that tailwind down hill:
Vhw,breakeven = Slope in degrees * distance to lift off with
no wind, no slope / (5*speed at lift off in KTAS)
where Vhw,breakeven is in knots and the distance to lift off
is in feet. With the same "constant" average force assumption the same
should be true for landing, making obvious changes. In actual fact the
above formula is a slight "simplification" of a somewhat more
complicated one.
The thing that messes up a lot of people is that you can have
three airplanes ready to take off on the same strip under the same
conditions and one of them (higher powered) is best off to go uphill
into the wind, one of them best off downhill with the wind, and with
the third it makes no difference (unless there are other
considerations like terrain clearance, etc.)
Hope this helps more than it confuses.