Using a wind component chart on final
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Using a wind component chart on final
Hello all,
This is my first PPRuNe post!
I am currently doing my PPL part time while working. I'm at the stage where I have completed about an hours worth of solo time.
Prior to flying circuits, my instructor taught me how to calculate the crosswind component using the clock method. I saw that you could also use the sin values. Both methods I understand, however, on final, my brain can't do the maths that quickly in addition to flying the plane and getting set up for a decent landing!
Is it frowned upon to have the wind component chart at the ready to find out the crosswind component for landing? :-s
Thanks in advance!
This is my first PPRuNe post!
I am currently doing my PPL part time while working. I'm at the stage where I have completed about an hours worth of solo time.
Prior to flying circuits, my instructor taught me how to calculate the crosswind component using the clock method. I saw that you could also use the sin values. Both methods I understand, however, on final, my brain can't do the maths that quickly in addition to flying the plane and getting set up for a decent landing!
Is it frowned upon to have the wind component chart at the ready to find out the crosswind component for landing? :-s
Thanks in advance!
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That probably depends on who you ask. But on finals with a crosswind landing ahead there are more important things to do than look up the exact value of the crosswind component from a chart. The wind speed and direction they give you are only approximat values anyway, so what's the point of deriving "exact" values from them using charts (or even worse: a calculator or smartphone app - yes those exist as well...)? Listen to your instructor I would say and estimate it using some rule of thumb!
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Aviation requires mental arithmetic skills. There will be those on the new fangled magenta line a/c, even worse the FBW brigade who will disagree. Any answers are always in the i-pad, FMC or Japanese brain in their flight bag. However, they have forgotten the most basic rule that the best computer on the a/c is between your ears; or it should be. A big shiny jet does not negate basic physics & arithmetic. In jets there are moments where legal limits come into force and need an instant decision. X-winds & tail winds are one of them, fuel flow & endurance in non-normal config another. And god forbid those guys who do load sheets on a calculator and still get it wrong.
In PPL light a/c flying there are many more scenarios, perhaps. 1 in 60 rule can be applied in many useful ways. Drift angles in holding patterns; wind vectors on finals another. I came from an era where mental maths was the norm and we kept it alive and well all through university. At flight school I'd become rusty and it was a hindrance. The excellent local pub had a dart board and that was the most enjoyable saving grace for removing the stress of VFR navigation calculations.
For wind vectors I always use 00 30 45 60 90. Headwinds are 100% .9.7.5.0. The x-wind is reversed starting with 100% at 90 degrees. It's easy. Throw away the calculator and engage the dormant grey cells.
In PPL light a/c flying there are many more scenarios, perhaps. 1 in 60 rule can be applied in many useful ways. Drift angles in holding patterns; wind vectors on finals another. I came from an era where mental maths was the norm and we kept it alive and well all through university. At flight school I'd become rusty and it was a hindrance. The excellent local pub had a dart board and that was the most enjoyable saving grace for removing the stress of VFR navigation calculations.
For wind vectors I always use 00 30 45 60 90. Headwinds are 100% .9.7.5.0. The x-wind is reversed starting with 100% at 90 degrees. It's easy. Throw away the calculator and engage the dormant grey cells.
Ok, there should be a windsock somewhere. Just take a look and see which way it is pointing relative to the runway, and if it is stable or lifting up and down. If it is moving a lot and at 90 degrees to the runway, and you are having to crab such that you are looking at the runway through the window at the side, then that is enough crosswind to land on a more into wind runway, or another airport.
No maths required.
Remember, you have two things to consider, direction and strength. Light wind at 90 degrees, no problem. Strong or gusting wind, you will have windshear to consider as well, and possibly difficulty taxi-ing. So that is why you calculate crosswind component WHEN PLANNING THE FLIGHT.
Not during the approach. You should leave the ground with a forecast that shows you landing where conditions are within your capabilities. Plan B comes into play when things change, weather forecasts aren't 100% after all.
On the approach it's all about sight picture and (dare I say this) feeling. Set up your approach at a comfortable height, flaps configured for landing, trimmed for the airspeed you have previously calculated. Use flight manual figures please. Make due allowance for gusts.
Then look at what is happening outside, as well as inside.
If the crab angle (or wing down, if you do it that way) is reasonable, and you are staying lined up with the runway, then carry on with an approach, with the mindset that you will be going around, and might convert to a landing if all goes perfectly. This way you get to see exactly what is happening before committing to a landing.
If you do this and are unhappy with the approach, you can always have another go. If it still isn't looking good, a different runway or diversion may be in order. You can always ask for a more suitable runway if you, the Captain, consider that is what you need.
As you gain experience you will be able to cope with more demanding conditions.
Practice with your instructor if you feel you are outside your comfort zone when flying solo.
If you do decide to land, fly the aircraft until it stops.
If you are flying a tailwheel type, fly the aircraft until it is tied down.
No maths required.
Remember, you have two things to consider, direction and strength. Light wind at 90 degrees, no problem. Strong or gusting wind, you will have windshear to consider as well, and possibly difficulty taxi-ing. So that is why you calculate crosswind component WHEN PLANNING THE FLIGHT.
Not during the approach. You should leave the ground with a forecast that shows you landing where conditions are within your capabilities. Plan B comes into play when things change, weather forecasts aren't 100% after all.
On the approach it's all about sight picture and (dare I say this) feeling. Set up your approach at a comfortable height, flaps configured for landing, trimmed for the airspeed you have previously calculated. Use flight manual figures please. Make due allowance for gusts.
Then look at what is happening outside, as well as inside.
If the crab angle (or wing down, if you do it that way) is reasonable, and you are staying lined up with the runway, then carry on with an approach, with the mindset that you will be going around, and might convert to a landing if all goes perfectly. This way you get to see exactly what is happening before committing to a landing.
If you do this and are unhappy with the approach, you can always have another go. If it still isn't looking good, a different runway or diversion may be in order. You can always ask for a more suitable runway if you, the Captain, consider that is what you need.
As you gain experience you will be able to cope with more demanding conditions.
Practice with your instructor if you feel you are outside your comfort zone when flying solo.
If you do decide to land, fly the aircraft until it stops.
If you are flying a tailwheel type, fly the aircraft until it is tied down.
The one important point is to know which side to dip into the crosswind. All the rest must come from your symbiose with the aeroplane - it will tell you what it needs, though some have a gentler expression than others.
[[ edit: typed at the same time as @Piper.Classique - as usual, there's not much to add to her words. I particularly like the "carry on with an approach, with the mindset that you will be going around, and might convert to a landing if all goes perfectly"]]
[[ edit: typed at the same time as @Piper.Classique - as usual, there's not much to add to her words. I particularly like the "carry on with an approach, with the mindset that you will be going around, and might convert to a landing if all goes perfectly"]]
The time for using a calculator is well before entering the zone.
On final the wind will be changing on descent. The airplane will be telling you if there's too much x wind (although in a glider you likely don't have the choice of going to another airfield).
Trees, terrain and hangars upwind of the runway can have major influence on the wind.
I recall a Bob Stevens cartoon about a pilot with several different calculators for every conceivable phase of flight. The Salvage Value calculator was put in use at the end of that flight.
On final the wind will be changing on descent. The airplane will be telling you if there's too much x wind (although in a glider you likely don't have the choice of going to another airfield).
Trees, terrain and hangars upwind of the runway can have major influence on the wind.
I recall a Bob Stevens cartoon about a pilot with several different calculators for every conceivable phase of flight. The Salvage Value calculator was put in use at the end of that flight.
Keep it simple. Figure out the difference between the wind and the runway heading, e.g. if you're on 31 and the wind is 330, it's 20 degrees. If it's 60 or less, divideit by 60, e.g. for 20 degrees it's 1/3. And multiply that by the wind strength, e.g. if it's 15 knots, you have a 5 knot crosswind component. This is easy to do in your head, and is at least as accurate as the information you're being given in the first place. If the difference is more than 60, take the wind strength as the crosswind.
Details... the error is never more than 14% (at 60°). The wind direction and strength are less accurate than that. You don't need an accurate number - what are you going to do with it? The only reason you need to know anything at all is to know whether you even want to try the landing. So if the wind strength is less than your crosswind limit (set by you, the aircraft, or your school), it's of no importance. If you're trying to land in a 40 knot wind it does matter, but that doesn't happen often and you'd better be prepared to go around at every 10th of a second.
Of course for a written exam they want the answer to the nearest 100th of a knot, and for that you do need some kind of chart or calculator. But don't confuse what happens in a written exam with actual flying.
Details... the error is never more than 14% (at 60°). The wind direction and strength are less accurate than that. You don't need an accurate number - what are you going to do with it? The only reason you need to know anything at all is to know whether you even want to try the landing. So if the wind strength is less than your crosswind limit (set by you, the aircraft, or your school), it's of no importance. If you're trying to land in a 40 knot wind it does matter, but that doesn't happen often and you'd better be prepared to go around at every 10th of a second.
Of course for a written exam they want the answer to the nearest 100th of a knot, and for that you do need some kind of chart or calculator. But don't confuse what happens in a written exam with actual flying.
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Here's the easy way (as per RAT 5). Remember three numbers. Point 5, 7 & 9. With a wind 30 degrees off the runway, the crosswind component is 0.5. At 45 degrees it is 0.7. You can already guess what it is for 60 degrees. The same applies for headwind/tailwind components. These values are also good enough for cross country planning.
PM
PM
Last edited by Piltdown Man; 24th Jul 2017 at 17:41.
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Get your instructor to show you how to use the VOR to estimate cross-wind component - it's accurate and simple - also, at a glance, you have an indication of head or (hopefully not) tail wind component.
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[QUOTE=bose-x;9840772]Blimey. Just look at the windsock. You really don't need to know numbers.[/QUOTE
It is a good idea to use a simple system 30/45/60 degrees from the early days so that when you need to assess the crosswind in IMC it is second nature. It's is actually very easy.
Look at your watch 30 degrees = 30 minutes= half an hour...half the wind is cross wind.
45 degrees is 3/4 of an hour = 3/4 of the wind is cross wind
60 degrees is a full hour...all crosswind.
It is a good idea to use a simple system 30/45/60 degrees from the early days so that when you need to assess the crosswind in IMC it is second nature. It's is actually very easy.
Look at your watch 30 degrees = 30 minutes= half an hour...half the wind is cross wind.
45 degrees is 3/4 of an hour = 3/4 of the wind is cross wind
60 degrees is a full hour...all crosswind.
I don't look at the windsock on short final. I just sideslip to keep the aircraft pointing along the runway, and staying in the centre of it.
And get one wheel on the runway.
And get one wheel on the runway.
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It is helpful to be able to assess the wind vector well in advance of venturing into the vicinity of a runway where there maybe a windsock in sight. I challenge you to find a windsock near the threshold of a major airfield. there is one somewhere, but try finding it visually as you wrestle your guided ping-pong ball down finals. Before you set out you can decode the METAR/TAF and when approaching the airfield the tower will give you the recorded wind. You need to be able to decide quickly if you are going to continue. If it is close to limits, and you do continue, you need confirmation on short finals to be 'comfortable'. What is wrong with expecting pilots to do some mental gymnastics? It should be par for the course.
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To answer the original question, you won't want to be looking at charts on final, you'll be fully occupied with flying the aircraft.
As you fly down the extended centreline it will be obvious whether you're crabbing to the left or to the right ... indeed after not very much more experience than you already have it will have been obvious whether flying down base leg has taken a longer or shorter time than usual, and it will be obvious whether you've struggled to make the extended centreline (headwind) or whether you've overshot it (tailwind).
Any or all of which tells you the direction the crosswind is coming from, even if you didn't do any homework before take-off and didn't remember what happened at take-off and didn't look at the windsock whilst downwind.
So there are two things left that you care about: whether you can land safely, and whether you can land legally (aircraft limits, club rules, whatever). And at your stage you're almost certain to form the judgement that you don't like it, and that you're therefore going to go around, long before "legally" becomes an issue.
One day "legally" will become an issue - say you're happy landing with an 18kt crosswind, 'cos you've done it dual, but the club limit for solo is 15kt - and you'll then want to be able to do the arithmetic. If you can't do "one sixth of the wind speed per ten degrees off runway heading" in your head there are other parts of the course you'll struggle more with.
As you fly down the extended centreline it will be obvious whether you're crabbing to the left or to the right ... indeed after not very much more experience than you already have it will have been obvious whether flying down base leg has taken a longer or shorter time than usual, and it will be obvious whether you've struggled to make the extended centreline (headwind) or whether you've overshot it (tailwind).
Any or all of which tells you the direction the crosswind is coming from, even if you didn't do any homework before take-off and didn't remember what happened at take-off and didn't look at the windsock whilst downwind.
So there are two things left that you care about: whether you can land safely, and whether you can land legally (aircraft limits, club rules, whatever). And at your stage you're almost certain to form the judgement that you don't like it, and that you're therefore going to go around, long before "legally" becomes an issue.
One day "legally" will become an issue - say you're happy landing with an 18kt crosswind, 'cos you've done it dual, but the club limit for solo is 15kt - and you'll then want to be able to do the arithmetic. If you can't do "one sixth of the wind speed per ten degrees off runway heading" in your head there are other parts of the course you'll struggle more with.
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Thanks for all the suggestions!
Hello everyone, thank you all for your replies and suggestions :-).
To be honest, in all this time, I have never seen the windsock on final! I am trying too much to focus on landing rather than look elsewhere other than the runway. Next lesson I will make an effort to look for it! :-D
I do check the METAR every day even at work just to get my head into that different "language" and try to calculate the crosswind from that then check if I am correct. This helps...and it also helps that I am in the comfort of my desk haha.
I like the sound of keeping things simple by using the 30,45,60 rule, but for the exams I better practice the more accurate methods. I guess practice makes perfect. My limit is 17kts and fortunately (or unfortunately as it could be good practice) it has never really been close to the limit. I haven't really done any serious crabbing either...I think I will get a shock when I will have to haha.
Thanks again for all your replies. So helpful!
Fran
To be honest, in all this time, I have never seen the windsock on final! I am trying too much to focus on landing rather than look elsewhere other than the runway. Next lesson I will make an effort to look for it! :-D
I do check the METAR every day even at work just to get my head into that different "language" and try to calculate the crosswind from that then check if I am correct. This helps...and it also helps that I am in the comfort of my desk haha.
I like the sound of keeping things simple by using the 30,45,60 rule, but for the exams I better practice the more accurate methods. I guess practice makes perfect. My limit is 17kts and fortunately (or unfortunately as it could be good practice) it has never really been close to the limit. I haven't really done any serious crabbing either...I think I will get a shock when I will have to haha.
Thanks again for all your replies. So helpful!
Fran
One other thing, often (not always) the wind at surface level is less than on your approach - so don't worry too much if it all seems a lot as you descend. There is a (good) chance that when you get to the tricky bit the wind has calmed somewhat.
Or, put another way, don't throw your approach away too early...
Or, put another way, don't throw your approach away too early...
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Or, put another way, don't throw your approach away too early...
I think the best thing you can do is use your watch method, and keep practising. ( [difference between runway and wind direction] divided by 60 ) times wind speed. 250/10 on runway 21 means 40 degrees difference. 40/60 is the same as 4/6 which is equal to 2/3. 2/3 of 10 is roughly 7kts and that is roughly your crosswind. You don't need to use exact figures... If it was 235/10 on runway 21, thats 25degrees difference, 25/60 is roughly 30/60 = half, so the crosswind will be slightly less than 5kts. Keep coming up with random numbers and random runway headings over breakfast, lunch, dinner, whilst watching TV...etc... and keep doing them whilst eating / watching TV until you feel confident with it. (the multi-tasking helps to make the figures easier when overloaded during flight).
With experience, although if you intend to go commercial, you will need to do them before every landing, you may not need to know the exact figure, just to be aware which side the crosswind is. 17kts is the "demonstrated crosswind limit" of the PA28, with experience and skill however, one's limit may differ from the book figure (providing insurance and club rules don't prevail of course).
Keep at it - they'll become second nature! That'll be really useful for your GFT (or whatever it is now called).
Good luck with your learning!