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Where is the wind coming from?


mrkik
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This is something I have struggled with before. In fact, it was part of the reason I failed my private pilot checkride. When I was doing an off airport, I made a downwind landing. The winds were calm, but there was still a little bit of wind. I just had a hard time telling where it was coming from. There was no smoke, no water, or any other wind indication that I could tell except feeling the aircraft get blown around.

 

Perhaps it is inexperience, but I have a hard time telling where the wind is simply by the way the aircraft moves in the wind. Obviously, when the winds are strong, it is easy, but it's just the calm wind days that get me.

 

So how do you tell which direction the wind is coming from on a somewhat calm day? Specifically for an off airport landing (not near an awos/atis). Also there is no smoke, or any other visual wind indicators. This is just something I want to improve on and need some help figuring out.

 

Also, if this is the wrong board, feel free to move it to the correct place.

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If the wind is really light (<5kts) and there aren't any visual clues, you may just have to take a guess and make a test approach to find out what is going on.

 

Make this an "overshoot approach". Fly a stable constant angle approach with a loaded disc, but don't actually descent into the confined area. Stay above any obstacles so you can go around without trouble.

Observe your airspeed indicator, look at your balance string(s), and try to feel when the aircraft is losing ETL. If the airspeed is lower than the perceived groundspeed, the balance strings go limp early on, or you feel you are losing ETL even though you are still moving fairly fast, you are downwind.

Observing the balance string(s), you can even get a fairly accurate idea of wind direction once you slow down enough.

 

This approach should be flown to a go-around, and you should obviously be telling the DPE what you are going to do.

 

 

Another tip: birds are a fairly reliable wind indicator if there are any in the confined area. They almost always take off and land into wind.

Edited by lelebebbel
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Not having any idea of where you are or what your local terrain is, only general advice:

Keep track of the wind from the beginning. Look at the METAR map station depictions for an overview.

Where's the wind at departure?

Enroute, look for smoke, flags, trees, bodies of water, dust, etc. I put that "into my pocket(s)" left rear hip, both back pockets, right side front, of just cuss the headwind and look forward to a tailwind on return.

Flip through some AWOS stations on your enroute leg.

Approaching destination, reinforce that by looking for local influences, ridges, structures, open fields.

The high recon confirms or corrects, it's way to late to decide wind direction without obvious tells.

Unless there's strong local influences or the flights really long, the wind will be where it was. Except when it's light and variable, kind of what you describe, then the local effects are much more influential even if less consequential. The difference in landing with a 2 knot tail wind and a 2 knot headwind isn't enough to make me vary my approach path from the best forced landing areas. Unless I'm really power limited and have no better option than using all my skill and experience to get in and out. If that's the case, I know where the wind is and check it constantly, as above, and use the feel and eye developed by doing tens of thousands of approaches and departures... Which isn't textually conveyable into very general advice.

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This is one of the reasons I bought a GPS! Groundspeed vs. airspeed, it really helps during those times when there just aren't any good visual cues!

 

Just make sure you're comparing ground speed vs true airspeed and not indicated.

 

On a recent cross country we were comparing the ground speed on GPS to our airspeed by computing our TAS on the performance page vs our IAS. At 2000 feet we had a 10 knot difference, so even though my GS was 115 knots and my indicated was 105, in reality we didn't have a tail wind. A few guys in the flight made that mistake and thought we had a 10 knot tail wind.

Edited by SBuzzkill
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Just make sure you're comparing ground speed vs true airspeed and not indicated.

 

On a recent cross country we were comparing the ground speed on GPS to our airspeed by computing our TAS on the performance page vs our IAS. At 2000 feet we had a 10 knot difference, so even though my GS was 115 knots and my indicated was 105, in reality we didn't have a tail wind. A few guys in the flight made that mistake and thought we had a 10 knot tail wind.

The rule of thumb is TAS increases by 5 knots per 1,000 feet.

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Just make sure you're comparing ground speed vs true airspeed and not indicated.

 

On a recent cross country we were comparing the ground speed on GPS to our airspeed by computing our TAS on the performance page vs our IAS. At 2000 feet we had a 10 knot difference, so even though my GS was 115 knots and my indicated was 105, in reality we didn't have a tail wind. A few guys in the flight made that mistake and thought we had a 10 knot tail wind.

 

105KTS indicated? Pulling her guts out weren't you? :lol:

Edited by akscott60
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~90% IIRC. It was a reset trip so they didn't have any armament on the UWPs. We had to cover about 600nm that day so we were boogying. When we were below 400lbs fuel I had a hard time keeping it below VNE while staying with lead.

Edited by SBuzzkill
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