Alioth wrote:
maintain whatever it requires to run straight (it’s important to do this in a tailwheel aircraft)
Yes, especially if constrained by a very narrow runway, but in practice many commercial runways are wide enough to take off in an arc or parabola.
A technique shown to me by a floatplane instructor is to “line up” 15-25 degrees to the right of one’s chosen “runway”, and then allow the P-factor to pull the ship straight. I often do so with my taildragger – not least because it enables me to see the runway for those first 2-3 seconds until the tail comes up. In theory it may also shorten the take-off roll.
Once, when aiming to land at LESB after a 2-hour trip years ago I was aghast to find the forecast 15KT xwind had changed to 330@20G30 (rwy then was 06-24) with hangars or houses upwind at both ends of the runway making for what @Dan calls an interesting landing…with the Mrs and kids onboard it is more like a “horrible” experience.
I simply diverted to LEPA’s 70-m wide runway (also 06-24, and only 1nm away from LESB) and landed diagonally across it for an easy peasy smooth wing-low crab-less landing…ah the old times when the cost of such a diversion was only 20€ + taxi ride (vs today’s 1000€)
Dan wrote:
Seldom does one encounter 90° crosswinds upon landing
However, one must remember that anything more than about 45° is almost as much. The crosswind component at 45 is already 70% of the windspeed, and the crosswind component at 60 degrees is 87% of the windspeed.
One thing that people often forget from their PPL Met training is the gust reporting factors.
Often I find someone is perfectly happy with 15Kts cross wind, but won’t fly with 15G25.
In reality the 15 Kts could be 15G0 or 15G24, because the gust factor is only reported when it reaches 10kts or more (or is it more then 10 kts??).
And the gust factor is just the highest gust in the last 10 minutes (if I remember that correctly!). So it could be really gusty every few seconds or just one freak gust 10 minutes ago.
Personally I don’t get too bothered about gust factor so long as I’m happy with the average. Once you get more than 15kts there will always be some gusts whether they are reported or not.
The bigger the airport, the higher the wind speed tends to be but with smaller gusts. Bigger airports tend to have more open space allowing for stabilising of the wind flow.
I notice that Dublin airport always has stronger winds that Weston where the trees provide some shelter for Weston, but that then contributes to some gustiness that isn’t as much of an issue at Dublin.
dublinpilot wrote:
Often I find someone is perfectly happy with 15Kts cross wind, but won’t fly with 15G25.In reality the 15 Kts could be 15G0 or 15G24, because the gust factor is only reported when it reaches 10kts or more (or is it more then 10 kts??).
I see your point, but you have to draw the line somewhere.
For me the important factor for crosswind landing is my currency in crosswind landings.
EGPE Inverness is great, with gusty crosswinds on main runway 05/23 at times, but with 11/29 available.
My limit on bumpy grass is much less for a full stop, as I could bounce into the air at an airspeed I could not keep control.
Maoraigh wrote:
For me the important factor for crosswind landing is my currency in crosswind landings.
I really agree with this. I think keeping track of conditions of recent landing helps a lot. It may make sense to adjust the limit based on recent experience.
dublinpilot wrote:
In reality the 15 Kts could be 15G0 or 15G24, because the gust factor is only reported when it reaches 10kts or more (or is it more then 10 kts??).
I also feel it can be hard to know what are the real condition of a landing for the purpose on determine currency and limit. A reported direct xwind at 15G29KT for example: what did it really mean?
For those of us lucky enough to have avionics that can upload to FlySto you can actually review a very useful wind on landing analysis.
I am starting to use this graph from the recent flight history to help decide and adjust my limit.
As you can see, while the METAR was 15G29KT in this case, in practice it was much milder.
roznet wrote:
upload to FlySto you can actually review a very useful wind on landing analysis
Hadn’t noticed this one, thanks @roznet 🙏🏻
Obviously one could spend more time analysing data than the duration of the flight itself… once more FlySto rocks 😎
As alluded to by others, the location of the runway can also matter. Here at ENVA, if the wind is from the south (between 120° and 220°) it usually also is fairly strong and very changing. There you should really forget about the average reported wind and focus on the gust indication, combined with the variable direction of the wind. When I was based in France, I would see report with wind directions in ranges superior to 45° mostly when the wind speed was under 5kt. Here it’s often a 15kt wind with direction 140 to 210° and gust 25, that will make for a very interesting landing, I prefer avoiding this kind of situations.
One tip for anyone landing at ENVA with winds from the south on R09, do your base leg aiming at the Runway threshold, turn a bit lower than usual in a short final over the runway and land further down (you will still have space, the runway is almost 3km long). That avoid being severely bounced around on final and give a little bit less wind at touch down point. This is because of the hills south of the airport which generate turbulence mostly at the threshold and before the threshold, a bit less further down the runway.
I got curious to hear what are your personal crosswind limits?
25 kts but I’d analyze possible gusts and terrain.
