Without relying on winds aloft or LLWS data, can pilots identify wind shear conditions visually, by watching clouds or otherwise?
Can you see wind shear? Nope, but you can sometimes see indications of it. According to Airbus, windshear is usually associated with the following weather situations (photos found on Google images by me and are clickable to take you to the source):
- Jet streams
- Mountain waves
- Frontal surfaces
- Thunderstorms and convective clouds (and I added virga here too)
Avoid these at all cost! Actually, that's the easy part. The windshear without the visible signs is more the issue, and csatlos's answer does a good job of telling you what to look for during flight (especially takeoff and landing when you are low and slow).
Clouds with flat tops or bottoms (anvil shapes) can indicate wind shear. Fronts are usually accompanied by wind direction and speed changes which can easily be seen in the clouds as the front approaches.
Smoke stacks can provide an indication of wind shear if smoke changes direction or shape as it rises.
3$\begingroup$ Another good trick is looking at two wind socks on the field at different heights (for example, one in a wind circle on the ground, and another on top of a hangar) -- If the wind socks can't agree on the wind direction there's a good chance you'll encounter wind shear somewhere between the top of the hangar and the ground. $\endgroup$– voretaq7Jan 3, 2014 at 21:31
$\begingroup$ @voretaq7 answer? $\endgroup$ Jan 4, 2014 at 17:58
Good photos, but there are many indirect wind indicators that can affect aircraft especially when in close proximity to the ground.
One I experienced between Whitehorse and anchorage at about FL330 was a 9° temperature rise. A couple minutes later I flew into sever turbulence for about 30 seconds. The turbulence stopped and the temperature went back down. I was above an overcast and clear above but I could see through a small hole in the clouds some mountain tops. I check a chart and there was a mountain about 18 thousand feet tall. I figured that the cause was mechanical lifting of the jet stream over the mountains and I few through the burble on the backside of the mountain which cased the temperature to rise. So be very careful around mountains, things can happen with or without clouds as show in another comment.
Other things to look for that a lot of pilots may not be aware of is to learn the surroundings of the airports that you intend on flying into even your home base. Look for major features that could have an affect on wind. For example Hot Springs, VA has a mountain top airport and the wind blows upward and over the far end of the runway and then down to the runway a few thousand feet toward to departure end. What effect the wind has on an airplane as it enters the null area of little wind is that there is little acceleration on the airspeed indicator. The airspeed indicator also indicates the effect of the wind over your wings which can be very interesting.
If you are close to large bodies of water and the airport is within a couple of mile from the water there can be very strong changes in the wind direction. I was on final at 3000 ft. with a strong wind from the right with a crab that caused me to view the runway through my side window. As I descended to within about 600 ft. I got into lake effect wind and ended up turning the airplane about 60° left to keep lined up with the runway.
Look for quarries and undulating land features that can indicate airflow. You cannot see the air but you can certainly see the land features that will give you a pretty good idea what to expect. Just this last weekend a corporate jet, after making a go around in Aspen tried to land on the second attempt and crashed. The wind was from the northwest 15 gusting to 25 kts. Aspen has a large mountain just to the west side of the runway and the pilot was attempted a down hill landing with the far end of the runway 200 ft. lower than the approach end which is at the max allowable of 2%. Aspen id 7800' AGL.
There are a lot of wind gotcha's out there, this is a good topic keep them coming guys.
A combination or one or more of the following conditions may indicate wind shear is present:
- Indicated airspeed variations in excess of 15 knots
- Groundspeed variations (decreasing head wind or increasing tail wind, or a shift from head wind to tail wind)
- Vertical-speed excursions of 500 fpm or more
- Pitch attitude excursions of five degrees or more
- Glideslope deviation of one dot or more
- Heading variations of 10 degrees or more
- Unusual autothrottle activity or throttle lever position
These are visual indications in the sense that you're looking at the way the aircraft is performing versus out the window for cues from the environment.