ILS Crosswind landing question

[Gun Jam]

The trouble im having is determining how much rudder should be applied to keep the ILS bars lined up on the ADI.

 

For example im 6 miles out on approach on the glide slope with the horizontal ils bar on the dot in the center of the ADI. There is a crosswind that is attempting to blow the plane off the runway center line so I apply rudder correction to keep the plane on the center line and the vertical ILS bar on the dot in the center of the ADI.

 

The problem I am having is I'm always chasing the vertical ILS bar because I have no reference of where my slip angle should be to compensate for the crosswind. I watch the bar and I see it move to the left so I add more corrective rudder and it comes back to the center and I start reducing rudder in hopes it stays in the center but Im always off just a tad so its always drifting off center.

 

What other reference points can I use along with the Vertical ILS bar to determine how much more or less rudder I should be applying at any given time???

 

Thanks

 

-Gun

[Cibit]

Have you tried to roll slightly in the direction away from the wind is blowing rather than rudder which are big and coarse on the hog and fly the line

[Magician]

If your HUD and EGI are operational, you can line up the TVV with the waypoint marker for the airbase, that'ss give you close to the right crab angle, and if the Localiser bar is centered, you're lined up with the runway.

[Magician]

Oh and don't use just rudder to turn the plane, that tends to only change the direction the nose is pointing without changing the direction the plane is going through the air. That's the wrong kind of crabbing.

 

You need to crab with respect to the ground, not the air.

[carrollhead]

Once you turn inbound at the start of the approach, fly directly down the runway heading (these values are often not what you see on the map - there's a couple of degrees difference). At first, be at or close to your planned landing speed - say 130 kts. The needle should be centred at this point.

 

Observe which direction the CDI needle moves. Once it starts to get offset, then turn the aircraft toward it, say 5 degrees and stabilise. You'll be descending on the glideslope too. Wait to see what your new heading does to the localiser needle. You'll either need to turn into the wind a little more or turn back toward the runway. Keep making these small corrections until you stabilise on the correct heading.

 

Holding speed is important here, otherwise you'll make the solution more complicated.

 

Flying in a sideslip will make handling the jet a lot more complicated!

 

To give you an example of how to work it out, imagine a plane landing in a direct 10kt crosswind with an IAS of 130 kts. (I know I'm simplyfying the maths a little here - I don't think it's enough to worry about!)

 

The required crab angle is 4.4 degrees (sin^-1 (10/130))

 

At 150 kts it's 3.8 deg (which is over accurate I know!)

 

 

Since I don't know anyone who can fly to 0.5 of a degree, hold an exact speed etc etc - try the method above. Give yourself plenty of room to get stabilised (10 miles or so at first) and be patient to see the results of your corrections.

 

Once you get the hang of it you can fly at a higher approach speed until you get to 3-4 miles and then slow it down.

 

Only when you get into the visual environment, and can see the runway should you transition to a sideslip in order to land (in fact you can do this in the last few seconds of flight with practice).

 

Hope that helps - you can also practice course corrections like this using TACAN. Just fly inbound with a crosswind and practice keeping the needle centred. The only difference is that the ILS needle is a lot more sensitive.

[Cibit]

Try some of my missions I made ages ago. I still fly them occasionally myself to keep my hand in

http://forums.eagle.ru/showthread.php?t=75189.

 

IMO ILS should mean no visuals. Have fun:music_whistling:

[Gun Jam]

Hello

Thanks for all your help.

 

Following the advice and using roll angle into the wind rather than rudder yaw alone has made improvements!

 

I found that I was having to use a bit of rudder as well to stop the plane from descending while maintaining a roll angle.

 

now my question is this Magician suggested using the TVV to keep the plane inline with the runway during a cross wind approach. This would be great as it provides a ton of feedback allowing correction before the ILS bars get out of line.

 

By my experience has been that the TVV only indicate a point of impact not a heading of impact.. if placed on a ground object the plane will impact that location but it does not seem to correct for wind drift. In a crosswind approach if I keep the TVV on the threshold wp marker the plane seems to fly and arc as it approaches the runway so that by the time I am within 2 miles of the runway I am approaching the runway way off center-line and mostly pointed into the wind (remember this started out as crosswind)

 

It seems to keep the plane on the center-line the TVV must remain upwind of the wp marker and not centered in the wp marker box as it would be in zero wind.

 

Is this correct or am I screwing up?

 

Thanks

 

-Gun

[Magician]

Hello

Thanks for all your help.

 

Following the advice and using roll angle into the wind rather than rudder yaw alone has made improvements!

 

I found that I was having to use a bit of rudder as well to stop the plane from descending while maintaining a roll angle.

 

now my question is this Magician suggested using the TVV to keep the plane inline with the runway during a cross wind approach. This would be great as it provides a ton of feedback allowing correction before the ILS bars get out of line.

 

By my experience has been that the TVV only indicate a point of impact not a heading of impact.. if placed on a ground object the plane will impact that location but it does not seem to correct for wind drift. In a crosswind approach if I keep the TVV on the threshold wp marker the plane seems to fly and arc as it approaches the runway so that by the time I am within 2 miles of the runway I am approaching the runway way off center-line and mostly pointed into the wind (remember this started out as crosswind)

 

It seems to keep the plane on the center-line the TVV must remain upwind of the wp marker and not centered in the wp marker box as it would be in zero wind.

 

Is this correct or am I screwing up?

 

Thanks

 

-Gun

 

Bare in mind that the ILS indicators have to remain centered.

 

The TVV should be off center in the HUD if you have a crosswind, and the waypoint marker (the square symbol) should also be kept off center, lined up on a vertical line with the TVV.

 

In fact, you should keep the TVV a little below the waypoint marker since the marker is halfway down the runway. But the glideslope indicator is what rules. Just as the localizer indication is. the TVV should only be a guide to how far into the wind from runway heading you should fly.

 

Also you should maintain that heading wings level without rudder (You want to crab with respect to the ground, not the air), and only turn (with aileron and rudder) to correct any drift. and only use the rudder to sideslip just before touchdown to line up the wheels with the runway.

[Gun Jam]

Thanks Magician

 

Maybe Im simply letting the plane drift too far before I get the TVV on the WP indicator.

 

Now if the cross wind is constant shouldn't I be applying a predictable constant corrective input? In the last sentence you seem to imply that I should fly down the runway center line without using rudder or roll concretion with wings level this obviously wont work as the plane would be blown off center line just like a bullet in a crosswind so I should be using a constant amount of roll angle as I head towards the runway correct??

 

Thanks again

 

-Gun

[Magician]

Thanks Magician

 

Maybe Im simply letting the plane drift too far before I get the TVV on the WP indicator.

 

Now if the cross wind is constant shouldn't I be applying a predictable constant corrective input? In the last sentence you seem to imply that I should fly down the runway center line without using rudder or roll concretion with wings level this obviously wont work as the plane would be blown off center line just like a bullet in a crosswind so I should be using a constant amount of roll angle as I head towards the runway correct??

 

Thanks again

 

-Gun

No you should fly wings level (no rudder or bank) with your nose pointed into the wind from runway heading (so that the off center TVV is lined up with the waypoint marker/runway). Don't worry about lining up the plane's axis with the runway until you are about to touch down.

 

The TVV shows the direction your plane is actually going, so if you are on the localizer, and you keep the TVV on the runway/wp marker, you will not drift from inline with the runway. And once again, only side slip through the air with the rudder when you are about to touch down, so you don't land with the wheels pointed sideways.

[drsgfire]

No you should fly wings level (no rudder or bank) with your nose pointed into the wind from runway heading (so that the off center TVV is lined up with the waypoint marker/runway). Don't worry about lining up the plane's axis with the runway until you are about to touch down.

 

The TVV shows the direction your plane is actually going, so if you are on the localizer, and you keep the TVV on the runway/wp marker, you will not drift from inline with the runway. And once again, only side slip through the air with the rudder when you are about to touch down, so you don't land with the wheels pointed sideways.

 

I agree. Though you could use the sideslip approach but I find that it involves to many inputs at one time on the approach. I can do it but I prefer to just De-Crab before touchdown and call it a day. It would have to be one heck of a cross wind for me to use sideslip.

[Yurgon]

 

Note #1: This is the very old Nevada map, not the new one.

 

Note #2: Although the video was taken with an early Beta release of A-10C, everything documented about crosswind ladings still holds true for the current version AFAIK.

[Fish]

You don't use rudder to keep aligned, that's very inefficient, and frankly unstable. You 'point' the aircraft into the wind, when lined with it. The Hud symbology in the A10 corrects, by shifting out of the wind. so to center it, you are forced to point 'upwind' So you 'crab' into the threshold. I tend to describe the hud as being 'blown downwind'. Helps me remember where the wind is comming from.

 

Then before touch down, apply rudder to straighten it up with the runway. If the wind is strong you might need to apply a little roll down of the windward wing. Also keep the nose up as long a possible after touch down, as its easier to control on the two wheels at this point. These CAS support aircraft are designed with large tail areas, which can make them a challenge to handle in high cross winds after wheels down.

 

Hope this helps.

Edited November 22, 2013 by Fish

[Gun Jam]

Im pretty sure I found the issue.

 

Im landing in a 25 knot wind with a good portion of that acting as a cross wind. The TVV has an arrow through it so I assume its not the true solution that's why the ILS bar and the plane come off center-line despite the TVV being dead on with the wp square the whole time.

 

I assume this is also why I have to keep the TVV off the WP square and well into the wind (opposite the TVV arrow direction) to keep the ILS bar and the plane on the center line.

 

And that brings us back to the initial problem / question. What can I use as a reference point to keep the ILS bar on center-line?

 

Does this help explain any of my issues?

 

In short if you've got an arrow through the TVV this means the TVV symbol is not the true vector correct? What do you do now?

 

Thanks

 

-Gun

[Fish]

Well there is a cross wind limit for all aircraft. In the A10 the hud is limited in size, so its gona get to its 'limit' of movement probbly before the 25knot cross wind mark (don't ask me what it is cause i was never in desperate need of knowing it). In that case you can't rely on following the TVV. The drift/co hud is merely a 'flight aid'. You cant' simply throw you hands up in the air and bail out, if it hits the limit!!

 

So. you need to then do a judgement of your crab angle using some other datum on the cockpit which intercepts the runway. Track with it for a bit, if you are sill drifting you are not pointing enough. You get the picture. It might require you to do a go around, if you haven't got it on the first try. I know it does not sound like a 'clean' solution, but real flying in variable weather is like that.

 

We are all a bit spoiled with A10, with its hud and avionics. Most of us virtual pilots have managed to escape, basic flight school, and flying in cross winds with nothing except the basic instruments to help. Real pilots would have learned to do that in something like a C172. Nice thing about basic flight training is, it works for all advanced aircraft no matter which, so if push comes to shove, it help you get along without the fancy stuff.

 

Excessiveheadspace video is best i've seen on the subject (Yurgon's link above).

 

 

 

 

 

Hope this helps.

Edited November 22, 2013 by Fish

[Magician]

Im pretty sure I found the issue.

 

Im landing in a 25 knot wind with a good portion of that acting as a cross wind. The TVV has an arrow through it so I assume its not the true solution that's why the ILS bar and the plane come off center-line despite the TVV being dead on with the wp square the whole time.

 

I assume this is also why I have to keep the TVV off the WP square and well into the wind (opposite the TVV arrow direction) to keep the ILS bar and the plane on the center line.

 

And that brings us back to the initial problem / question. What can I use as a reference point to keep the ILS bar on center-line?

 

Does this help explain any of my issues?

 

In short if you've got an arrow through the TVV this means the TVV symbol is not the true vector correct? What do you do now?

 

Thanks

 

-Gun

Yep, if the actual velocity vector is "off the HUD", the TVV won't help. And you have to do it "old school", by just adjusting into the wind back and forth until the localiser needle stops drifting. Or doing some "E6B" calculations to figure the correction angle ahead of time, and remembering it increases with lower speeds.

 

The above assumes no visual on the runway, with a visual you can use other references on the plane and the angle of the runway.

[Magician]

Here' a virtual E6B:

 

http://www.csgnetwork.com/e6bcalc.html

 

Use the third block down, titled: Heading, Ground Speed, And Wind Correction Angle

 

Enter wind speed, wind direction, approach speed under "True Airspeed", and runway heading under "Course"

 

Below, in the "Heading" box will be the heading to fly once on the localiser, and do your corrections around that heading to stay on the localiser. Keep in mind that if your airspeed is higher than what you entered, the heading should be little closer to the runway heading, and further from the runway heading if you are slower.

 

And here's an i-phone E6B app:

 

http://mye6b.com/

 

 

And sporty's has Android and Kindle apps as well as really really old school E6B's here:

 

http://www.sportys.com/source/features/search/search.cfm?catalog=PilotShop&question=e6b

Edited November 23, 2013 by Magician

[Gun Jam]

cool thanks!

[johnv2pt0]

Crab into the wind and fly the needles. I know absolutely 0 pilots that would break out an e6b although i suppose in a large crew aircraft it might be an option. However it's almost an exercise in futility as the wind will usually vary on your way down the glideslope. Fly the needles. You don't need a hud, and in fact I'd recommend turning it off sometimes to practice. We do that regularly because you never know what's going to fail. The benefit of flight sims is that you can practice (and mess up) as much as you want :)

[Magician]

Crab into the wind and fly the needles. I know absolutely 0 pilots that would break out an e6b although i suppose in a large crew aircraft it might be an option. However it's almost an exercise in futility as the wind will usually vary on your way down the glideslope. Fly the needles. You don't need a hud, and in fact I'd recommend turning it off sometimes to practice. We do that regularly because you never know what's going to fail. The benefit of flight sims is that you can practice (and mess up) as much as you want :)

 

It's still good to know what the crab angle should be as a starting point at least when you have no visual on the runway. With experience you don't need the calculator, but without experience it's better than spending all your time chasing the needles back and forth as you hunt for the right angle and over correct left and right.

[johnv2pt0]

It's still good to know what the crab angle should be as a starting point at least when you have no visual on the runway. With experience you don't need the calculator, but without experience it's better than spending all your time chasing the needles back and forth as you hunt for the right angle and over correct left and right.

 

Fair point.

[Headspace]

The landing fundamentals video isn't really intended to be a comprehensive guide to landing--it's a beginner's guide. It has a lot of gaps. It's not intended to be an ILS guide.

 

The other issue with is that I'd made it after a ~10 year hiatus from aviation, so it could be better. Eventually I will do a video about instrument stuff in DCS, it's just that it would require some kind of approach procedure which doesn't exist.

 

RE: the ILS, I wouldn't start slipping until you are on final and nearly about to land. Make sure you have visual contact with the runway.

Edited November 23, 2013 by Headspace

[Gun Jam]

Im doing these landings in heavy rain / thunder storms with cloud deck at 300m about a 20knt crosswind and some turbulence. In this case and ILS approach is needed.

 

By keeping the wings and rudder neutral and using light roll angle to correct for needle drift landings have become much much easier. This method is far more precise than rudder and or rudder mix. Simply watching the needle, thinking a bit ahead and using slight roll commands makes keeping the ILS bars in check much easier. Landings have improved a bunch.

 

Thanks guys!

[johnv2pt0]

If the wind is strong you might need to apply a little roll down of the windward wing. Also keep the nose up as long a possible after touch down, as its easier to control on the two wheels at this point. These CAS support aircraft are designed with large tail areas, which can make them a challenge to handle in high cross winds after wheels down.

 

Hope this helps.

 

For people that might read this later on, I'd like to correct a few things.

 

If the wind is strong you might need to apply a little roll down of the windward wing.

If there is any wind at all you will be applying aileron corrections. Otherwise you will be getting blown off course. The only thing that changes is how much. This in combination with opposite rudder once on short final is called the "wing low method." If anyone would like to learn more about it you can google it. In a one sentence explanation: the ailerons control your track while the rudder lines up your heading (wheels) with the runway.

 

Also keep the nose up as long a possible after touch down, as its easier to control on the two wheels at this point. These CAS support aircraft are designed with large tail areas, which can make them a challenge to handle in high cross winds after wheels down.

Two things here. If you're in a bad wx situation with some amount of moisture on the runway, you do not want to keep the nose off the ground. Doing this keeps the aoa higher, thus creating more lift and decreasing braking effectiveness. Also, there is the possibility of the nose slamming down because you waited too long to fly it down or because you applied the brakes. It also reduces visibility. And as an aside, irl you would want to track a little off centerline so your nosewheel is off the painted surface because it will have a slightly lower RCR (it's more slippery).

 

Second part is true but the solution isn't keeping the nose off. Remember that when you're rolling down the runway you are still creating lift. The wind will be trying to lift your windward wing off the ground, so you need to keep "flying" the airplane on the rollout. You will have to gradually increase the amount of crosswind control as you slow down because the airspeed over the control surface will be decreasing and thus will be less and less effective. Once again, if I didn't explain it well enough you can google :)

 

Glad you're getting the hang of it OP. I wish there was more instrument work available in DCS.

[Eagle7907]

ILS Crosswind landing question

 

I don't know about IRL A10 procedures, but IRL flying regional jets (somewhat comparable in size) the correct procedure is crabbing into the wind until about 200ft AGL, then put it into a slight slip landing with the main gear wheel into the wind first. Believe it or not, but my RL crosswind landings are smoother than my calm wind landings. :)

 

Use rudder during crabbing for very small corrections. Use aileron for larger corrections. Remember during landing the rudder is the most effective control, so don't over use the rudder during the slip, just enough to make the nose be straight with the runway while using aileron into the wind. The rudder WILL over power the ailerons.

 

Edit: Another thing, just realized this is about ILS. On many airplanes, the ILS antennas are located on the horizontal stabilizer, so rudder movement is not really recommended because IRL moving the tail actually causes the needles for the localizer indication to move or wiggle. (Probably not simulated on A10). That's why it's best to crab into the wind and when you have the runway in sight and 200ft AGL, kick the rudder, bring the wing down, slip it onto the runway.

Edited December 26, 2013 by Eagle7907