Landing With High Winds

[PaulN]

OK, I'll lead in with a hyperthetical that could become real one day.

 

I do all my usual flight planning, check the weather and decide it's OK to go. Jump into the CT at Newcastle to head home for Cooma on a lovely clear morning with an easy 10kt W wind. As the flight nears its end I notice the winds have increased alarmingly from what was forecast. On arrival at YCOM I see the winds are howling at around 25/30kt (like they are as I write) from SW.

 

The rwys are 18/36 and 14/32. The CT is rated for 13kt max xwind and I'm now a little anxious that fuel is getting low due to slower than expected flight into headwind. Added to this is the thought that I've only just got her back from repairs after being 13 mths grounded :ah_oh:.

 

Polo Flat is just a 5 min diversion but still 18/36 and 12/30. Adaminaby is 15 mins NNW with a very exposed rwy 09/27 and Jindabyne is 20 mins SW with rwys 12/30 and 09/27 but nestled at the foot of high hills with lots of rotor turb.

 

What would you do?

 

Paul

 

 

[Wilfred]

I agree with Chris

 

But it is also pretty hard to get caught out like that nowadays. If you are flying into an area with known wind strength or wind shear problems, you are always able to check the local conditions before you leave via phone or sites like wetherzone that allow you to look at real time local conditions. Its probably only a two hour flight so you should be able to determine pretty close to what conditions will be like when you get there.

 

If they don't suit you. Don't go>

 

 

[Ultralights]

i would go for runway 18, a 10kt crosswind should not be a problem.. i would refuel then do some circuits into said crosswind for the fun/experience of it..

 

though with a 10kt cross wind and a strong headwind component, make sure you make a steeper than usual approach.

 

 

[PaulN]

I would land on rwy 18 with a 30 knot wind from SW(225 degrees) this would interpret to a 10 knot cross wind component on rwy 18, which is inside of the envelope for the CT.

Chris,

 

My theory books and training say the crosswind component at 45 degrees to runway heading is 70% of wind strength, in this case that's 21kts.

 

See my dilemma?

 

Paul

 

 

[PaulN]

It is also pretty hard to get caught out like that nowadays. If you are flying into an area with known wind strength or wind shear problems, you are always able to check the local conditions before you leave via phone or sites like wetherzone that allow you to look at real time local conditions. Its probably only a two hour flight so you should be able to determine pretty close to what conditions will be like when you get there.If they don't suit you. Don't go>

Good comment Turtle ... and good practice.

 

Just for the sake of local knowledge for anyone flying into the Snowy Mtns area, it's not unknown for winds to come up unexpectedly and/or at greater velocity than forecast. We local flyers are always aware and looking for changes, and sometimes they come in quickly and with lots of turb off the hills to our west.

 

At least on one occasion during a flt from N'cle to Cooma I called ahead on mobile mid flight to a local pilot to learn of just this sort of thing. We diverted to Goulburn to hold over for improved winds, only a couple of hours and things were safer.

 

Paul

 

 

[PaulN]

Chris,

 

The images below are from my Aviation Theory Centre manuals. Does this help?

 

Paul

 

 

 

 

[Yenn]

Good results here and a very good idea to get us thinking. I am not aware of what it is like to fly a CT, but as the others I would go for Rwy 18, adding 5 kts for half the gust speed, although How you know what the wind speeds are exactly I am not sure. In addition I would aim to touch down on the left (Eastern ) side of the runway to give myself more leeway in case a gust pushes the tail round.

 

Ian Borg

 

 

[Student Pilot]

There's plenty (or there used to be) of AG strips down Cooma way, Polo Flat also has a cross strip with a fair choice of directions.

 

Better off having a go at a cross wind with plenty of fuel to spare than be forced into land or run out of fuel. Quite often with cross wind you get a lull now and again so shoot a couple of approaches and if it feels OK then land.

 

 

[Guest David C]

I always use the " mental arrithmatic " method when I fly . It's easy and accurate . Just multiply the angular difference by 1.5 , this becomes a % of the actual wind velocity . In this case 45 deg X1.5 =70% ( near enough ) . So 70% of 30Kts = 21Kts , this is near as damnit to your X wind velocity .

 

Dave

 

 

[bushpilot]

Hmmm - But what if it were 80o instead of 45o.. 80 X 1.5 = 120% - which doesn't make sense; so what am I missing?

 

 

[Ross]

X-Wind for 30 knots at 80 degrees

 

Wind x Sine of (wind Angle)

 

X-Wind = 30 x sine (80 degrees) = 30 x 0.98 = 29.54 knots X-Wind

 

Head wind = 30 x Cos (80) = 30 x 0.1736 = 5.2 knots

 

for 30 knots @ 60 degrees

 

X-Wind = 30 x sine(60) = 30 x 0.866 = 26 knots

 

Head Wind= 30 x cos(60) = 30 x 0.50 = 15 knots

 

for 30 knots @ 45 degrees

 

X-Wind= 30 x sine (45) = 30 x 0.707 = 21 knots

 

Head Wind = 30 x cos(45) = 30 x 0.707 = 21 knots

 

 

[Student Pilot]

All this is very well if the wind is consistant and is the forecast wind, very rarely in the real world are both true. Just land the Aircraft and worry about the classroom stuff when you get on the ground.

 

 

[Ross]

The point about the X-wind is that you do not need to remember the sine of a few angles.

 

The values have been shown to make the point that by the time the wind gets to 45 degrees off the track more than 70% of it becomes X-Wind!

 

Mostly remember how to read the wind sock especially for RAA AC with relatively low allowable X-Wind. Wind socks were probably designed for AC with performaces like that of typical RAA aicraft!

 

Put it another way;

 

you are getting;

 

almost half the wind velocity is X-Wind at a 1/4 of a right angle or 22.5 degrees

 

 

almost three quarters of the wind velocity is X-Wind at a 1/2 of a right angle or 45 degrees.

 

 

Sine of the following angles which is the multiplier to convert the wind value to X-wind value.

 

0 is 0.0

 

22.5 is 0.38 say 0.4

 

45 is 0.707 say 0.7

 

67.5 is 0.92 say 0.9

 

90 is 1.00

 

For the Cosine values, the multiplier for head wind, reverse the order of the values

 

So the message here is that above 45 degrees you have more than 70% of the wind as cross wind - read the wind sock for cross wind

 

 

below 22.5 degrees X-Wind is less than 40% of wind velocity and therefore head wind is closer to wind velocity- read the wind sock

 

 

 

[Ed Herring]

All this is very well if the wind is consistant and is the forecast wind, very rarely in the real world are both true. Just land the Aircraft and worry about the classroom stuff when you get on the ground.

Well Guy's & Girl's, Glenn's experience is showing! Above all FLY the Aircraft first. Don't be distracted by the science unless you have the ability to do so! Add speed to counteract the gusts and consider less flap!

 

Regards

 

Ed

 

 

[Guest pelorus32]

Here's a quandary for you: I tend to make better landings in tough conditions and in cross winds than I do otherwise. Not an absolute rule, but often the case.

 

I've discussed it with a couple of people. I think the consensus is that you are paying more attention, your feet and hands aren't asleep and generally you are more on the ball.

 

I enjoy crosswinds....don't know why.

 

BTW it's all relative, the only good thing about my landings is that the aircraft is undamaged and the occupants alive and well!!

 

Hooroo

 

Mike

 

 

[Ross]

Hi All

 

Here is another question which might have a bearing on the previous one by Mike.

 

I am yet to finish my J160 so I will go by the owner's manual.

 

What is the effect on stall speed for a maximum X-cross wind landing with the wind at right angles to the strip assuming MTOW and a X-wind of 14 Knots the max for the J160.

 

The stall speeds for zero flaps, first stage and second are quoted as 52 Knots, 47 Knots and 43 knots.

 

Jabiru for the J160 owners manual that I have say 14 knots X-wind has been demontrated at FULL Flap and to use full Flap for landing but they also say in strong X-wind conditions use the minimum flap consistent with the strip length available.

 

They also say use airspeed of 65 knots & full flaps for normal landing.

 

Also 60 knots for short field landing with full flaps.

 

Jabiru also recommend landing in X-wind using the into wind wing low for the whole approach & landing and land on main wheels first.

 

We could range here from a max cross wind to the strip when the wind is at right angles to a max cross wind when we have a wind say 22.5 degrees off strip. The latter case would be a wind a tad over 36 knots.

 

What are your thoughts on these situations.

 

Regards

 

 

[Yenn]

My understanding is that the cross wind should not make any difference to indicated Air Speed, but it will affect G.S.

 

There must be some effect on stall speed when you use the wing down to land in a cross wind. The total lift will be inclined not vertical and also the low wing will have more ground effect, but I doubt that it will be enough to be able to see on your ASI.

 

The idea of landing at different speeds accoeding to cross wind amount or even gusts seems odd to me, and may be the reason Jabiru's had a lot of nose wheel problems. I consider that it is best to land with the nose wheel well off the ground and that requires a slow speed. Good sport is watching Jabirus landing, the different techniques are very interesting, but I had better not shout too much I have only 1 Jab landing to my name. Ian borg

 

 

[Guest micgrace]

Hi All

 

Landing a Drifter in high winds is always interesting. Depending on conditions, may have to approach at 70+ knots (VNE 80 k) while having the stick buried in the far corners of the cockpit for the x wind, after a crab approach and when beginning roundout.

 

Needless to say, you really have your work cut out on landing (max x wind is only 15 knot, however it is possible in much worse than this) Not to forget the taxi either. The x wind WILL flip you over or at best, give a very fast taxi depending on vector component. Since Drifter Brakes are nonexistent, need to be aware of the tailwind to stop.

 

My $0.02 worth, Micgrace

 

 

[Guest Juliette Lima]

Hi Migrace,

 

Interested in your coments on landing the Drifter in moderate/strong winds. Thank you.

 

I'm trying to nail ALL my landings rather than 'lucking or bouncing' some of them and would appreciate your technique for 'average' winds (Drifter)....Do you approach with power, or glide? what are your approach speeds in moderate winds say up to variable 12 kts. ? Do you perfer to three point land or wheel on?

 

I know every landing is different and encountering sink or lift on final can impact on power decisions etc....however just seeking your 'rule of thumb' experience.

 

As a matter of interest, in strongish cross winds I approach the strip slightly downwind at an angle more into wind but aiming across the strip to a point100 metres up the strip on the oppisite side, and on landing, curve across the strip toward the centreline on slowing.....Takeoffs likewise from the into wind lower edge of the strip rather than centre... I have been doing this for a while based on logic before recently reading about ths technique from a very experienced pilot.

 

Brakes no problem on the 912 Fisher/Drifter....Wayne Fisher installed a hand brake with stacks of leverage.

 

I'm booking some time with Wally Rudin in March to 'hone' skills on the thruster and will be interested to see if he can improve my reaction/awareness time in the few seconds between flair and touchdown.

 

Regards

 

JL

 

 

[Guest micgrace]

Hi

 

Approach is done with power off. Maybe just a small trickle if undershooting, then off. Approach is crab like or side slip, which I prefer a little side slip to wash off height rather than add power.

 

Coming in at 70 knots means the stick is rather far foward to normal, then must straighten out before roundout and bury that stick in the far corners of the cockpit. (i've had it hard against my leg on some occassions with no movement left) Naturally doing a side slip to wash off height allows natural progression to this (but easy on return to normal control position)

 

The next trick is a roundout without bounce. let speed decay (although most is lost due to wind gradient) till wheels touch. VERY easy on back stick, too agressive and you will touch and bounce, but stick still far over to side wind is from then pull back all the way and your down. I still prefer to let the Drifter roll out rather than use brakes.

 

It takes quite a while to master this, for me has taken some 20 -30 hours to master starting from relatively mild conditions to marginal conditions (above max x wind where no one will fly), working up to it all the time. All I can say you get , very, very busy when landing. No time for theory, just practice, practice till it's natural.

 

I also add I regualrly go back to instructor on at least a monthly basis to cure bad habits before they develop. I now do this after having to undergo a BFR after moving regions and going through instructors whose main purpose seems to make dollars, not what is required. (please do not ask for who)

 

Micgrace

 

 

[Guest Juliette Lima]

Hi Migrace,

 

Thanks for your very detailed response. Now to digest, practice, and take advantage of skilled instruction. Incidently, just back from an hour at Cessnock, conditions 15kts almost across the strip, and very bumpy...lots and lots of work on final !!!

 

Thanks again for a very helpful response.

 

JL