Cross wind landings
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Only joking, mate, Hawarden is the place. Cross wind is a bastard there, comes in off those Welsh hills. Ur description of H as "sunny" is in fact remarkably correct. Hawarden is actually statistically the place which has most sunshine in the UK. It is regularly the hottest place in the country during summer, hence my tan.
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King Rooney, so you reckon you can land your C172 at 90kts?
A Cessna 172 will stall at around 55kts depending on weight (can't remember exactly) so at 90kts your aeroplane is still going to want to fly and won't be ready to settle down on the runway. You will likely bounce and get airborne again and in any case even if you manage a smooth touchdown the wing will still be producing a large amount of lift and there is probably going to be so little weight on the main wheels that it is going to begin to drift away from you. Don't forget too if you try to touch down at 90kts the aircraft is going to be in a level attitude (any attempt to flare is going to result in a HUGE baloon) so if you do try and land it, there is a strong chance that you'll land nosewheel first. The fin presents a large area, so it is going to weathercock and the wind is going to try and lift the upwind wing. You could put in a bit of wing down aileron to stop this happening, but at 90kts you will have a lot of aileron authority and you might end up groundlooping it. All in all, trying to manage an aeroplane hopping and skipping across the runway at cruise speed while trying to counteract the effects of a crosswind outside the manufacturer's limits isn't the best place to be. In a strong crosswind you are going to need to use the rudder and into wind aileron pretty much until you come to a halt, so your experimental techniques are going to get you into a lot of trouble.
My advice to you would be to find a better FTO and get a good insructor to sit down with you and go through the theory and practice of crosswind landings. You are paying them to teach you and if they're not, then you're being ripped off. Then go off and practice them with her or him. When you're off on your own, you should begin by landing in light crosswinds then as your experience builds, tackle some stronger ones. Maybe a post on the instructor's forum will generate some useful information for you?
But remember, if you are outside the manufacturer's limits then you're on your own.
A Cessna 172 will stall at around 55kts depending on weight (can't remember exactly) so at 90kts your aeroplane is still going to want to fly and won't be ready to settle down on the runway. You will likely bounce and get airborne again and in any case even if you manage a smooth touchdown the wing will still be producing a large amount of lift and there is probably going to be so little weight on the main wheels that it is going to begin to drift away from you. Don't forget too if you try to touch down at 90kts the aircraft is going to be in a level attitude (any attempt to flare is going to result in a HUGE baloon) so if you do try and land it, there is a strong chance that you'll land nosewheel first. The fin presents a large area, so it is going to weathercock and the wind is going to try and lift the upwind wing. You could put in a bit of wing down aileron to stop this happening, but at 90kts you will have a lot of aileron authority and you might end up groundlooping it. All in all, trying to manage an aeroplane hopping and skipping across the runway at cruise speed while trying to counteract the effects of a crosswind outside the manufacturer's limits isn't the best place to be. In a strong crosswind you are going to need to use the rudder and into wind aileron pretty much until you come to a halt, so your experimental techniques are going to get you into a lot of trouble.
My advice to you would be to find a better FTO and get a good insructor to sit down with you and go through the theory and practice of crosswind landings. You are paying them to teach you and if they're not, then you're being ripped off. Then go off and practice them with her or him. When you're off on your own, you should begin by landing in light crosswinds then as your experience builds, tackle some stronger ones. Maybe a post on the instructor's forum will generate some useful information for you?
But remember, if you are outside the manufacturer's limits then you're on your own.
Last edited by Hufty; 18th Feb 2006 at 21:59.
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If you intend to fly 737s in the future I would get used to the crab method as having the wing down will result in the engine scraping along the runway!
I don't like the wing down method myself, as it involves a fair amount of cross controlling and doesn't feel natural. Neither did the Army, where I did my training. I certainly wouldn't use it if I was learning by myself as you seem to be.
Phil
I don't like the wing down method myself, as it involves a fair amount of cross controlling and doesn't feel natural. Neither did the Army, where I did my training. I certainly wouldn't use it if I was learning by myself as you seem to be.
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The XW limit is the DEMONSTRATED limit, it is not the maximum that the ac could land in. It has been demonstrated by a test pilot up to that speed to be achievable by the average pilot. Now if you consider yourself an above average pilot as a student, your demonstrating that your not! The limit is there to stop people killing themselves, ignore it at your peril!
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The choice of wing-low or crabbed depends very much on the type of aircraft. As Paco says, a B737 needs to be landed crabbed because of its underslung wings.
But try flying something small and light with high wings - say a Piper Cub - crabbed, and as soon as you kick it straight the wind will pick it up and you'll loose the centre-line - wing-low is the only way to land that type of aircraft in anything other than very light cross-winds.
Most training aircraft - C172 included - can be landed using either method. The crab method is the one I prefer, purely because it can handle higher cross-winds than wing-low. I normally teach that to all my students. But if a student is having trouble with this method, I will teach them the wing-low method, and I'm quite happy for them to use that if they find it easier, because it is very much personal preference.
As for cross-wind limits, the 15kt "limit" on the C172 is not a limit, and it explicitly states this in the manual, in the definitions in Section 1:
(I've added the italics.) However, having said that, I would be very surprised at any school letting solo students fly with a crosswind of the kind you are describing..... 
FFF
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But try flying something small and light with high wings - say a Piper Cub - crabbed, and as soon as you kick it straight the wind will pick it up and you'll loose the centre-line - wing-low is the only way to land that type of aircraft in anything other than very light cross-winds.
Most training aircraft - C172 included - can be landed using either method. The crab method is the one I prefer, purely because it can handle higher cross-winds than wing-low. I normally teach that to all my students. But if a student is having trouble with this method, I will teach them the wing-low method, and I'm quite happy for them to use that if they find it easier, because it is very much personal preference.
As for cross-wind limits, the 15kt "limit" on the C172 is not a limit, and it explicitly states this in the manual, in the definitions in Section 1:
Demonstrated Crosswind Velocity is the velocity of the crosswind component for which adequate control of the airplane during takeoff and landing was actually demonstrated during certification tests. The value shown is not considered to be limiting.
FFF
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If any of you fly outside of the xwind limit, you are not insured at all. Do you fancy a bill for the aircraft, loss of earnings, airport crash if they are mean etc...
The crab techinque is ok till ground effect, then aim to drop the wing very slightly into wind to stop the drift. The risk of keeping the crab on till the last minute is cocking it up and exerting a side load, especially in a retractable. Rapid changes in rudder input require opposite aileron. This causes drag on all surfaces, mainly the lifting ones giving obvious downfalls.
If in a twin, do not put on too much bank or risk a prop strike. This is called the 'combination technique' and is the more commercial way of doing it.
If approaching in gusts, add half the gust factor to your normal approach speed eg wind 320 20G30 gust factor is 10 kts. Half is 5 kts so add 5 kts. BE76 short final is 85 so I would fly at 90kts to the threshold and add 5 kts to that giving 81kts. Check also you gust limit eg max of 30 with no Xwind Component.
These numbers all come from the Vmca speed and adding a factor to it. Vmca being the speed at which you have control in the air of your aircraft. It is a control and stability speed NOT a performance speed, so don't expect and favours if you get that slow, which a gust will do to you.
With the wing down method, you can, with skill, exceed the limit, bit it is very foolish. Don't forget that if you add roll and introduce a sideslip that you will get tailplane stall as the angle that it is introduced to the relative air flow is like sticking you arm out of the window, so a positive arrival may be needed, one wheel only very slightly before the other.
If in doubt, some instructors don't remember a great deal as you have to keep reading all of the time to remember it all, so you may not get the whole picture. Get a good book and learn why things are done. It may save you life and your pax.
Try and anticipate how much control input you need to reduce a draggy unstable approach...bad for you and worse for your pax.
The crab techinque is ok till ground effect, then aim to drop the wing very slightly into wind to stop the drift. The risk of keeping the crab on till the last minute is cocking it up and exerting a side load, especially in a retractable. Rapid changes in rudder input require opposite aileron. This causes drag on all surfaces, mainly the lifting ones giving obvious downfalls.
If in a twin, do not put on too much bank or risk a prop strike. This is called the 'combination technique' and is the more commercial way of doing it.
If approaching in gusts, add half the gust factor to your normal approach speed eg wind 320 20G30 gust factor is 10 kts. Half is 5 kts so add 5 kts. BE76 short final is 85 so I would fly at 90kts to the threshold and add 5 kts to that giving 81kts. Check also you gust limit eg max of 30 with no Xwind Component.
These numbers all come from the Vmca speed and adding a factor to it. Vmca being the speed at which you have control in the air of your aircraft. It is a control and stability speed NOT a performance speed, so don't expect and favours if you get that slow, which a gust will do to you.
With the wing down method, you can, with skill, exceed the limit, bit it is very foolish. Don't forget that if you add roll and introduce a sideslip that you will get tailplane stall as the angle that it is introduced to the relative air flow is like sticking you arm out of the window, so a positive arrival may be needed, one wheel only very slightly before the other.
If in doubt, some instructors don't remember a great deal as you have to keep reading all of the time to remember it all, so you may not get the whole picture. Get a good book and learn why things are done. It may save you life and your pax.
Try and anticipate how much control input you need to reduce a draggy unstable approach...bad for you and worse for your pax.
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Application of Common Sense and not trying to beat the system.
K R a little something to remember whilst ur trying to break yourself and kill a perfectly serviceable aeroplane, people on the ground are watching and you never know when the "authority" might also be watching. You might find a certain flight examiner debriefing you on x wind limits whilst bashing you accross the head with the nearest heavy thing, it also reflects quite poorly on your flight school that they allow to fly in such conditions when you must be at your most dangerous i.e not qualified and alone.
Also spare a thought for the chaps and f chaps that have to go outside in the cold or possibly the hot, pending how bad you mess up, to clear up your mess.
If you did click here you must feel quite disappointed, I can only offer the following advice:
Click here and follow the link to get £10000 p.a for free for life:
www.lebillyofthesilly.com
Also spare a thought for the chaps and f chaps that have to go outside in the cold or possibly the hot, pending how bad you mess up, to clear up your mess.
If you did click here you must feel quite disappointed, I can only offer the following advice:
Click here and follow the link to get £10000 p.a for free for life:
www.lebillyofthesilly.com
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If any of you fly outside of the xwind limit, you are not insured at all
As stated by several posters, the POH only ever states a DEMONSTRATED crosswind limit. This is not an absolute limit.
That does not mean that clubs/schools will not impose their own limits, because they will.
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Well, Andy R if you have an accident and you were attempting to land in a crosswind outside the aircraft's demonstrated limits then you are in a sticky situation nonetheless. If you injure anyone and you find yourself getting sued - it is going to be tough to defend your actions in such a situation. The "....well I know it is technically outside the limits but everybody does it" defence isn't a strong one.
You're right that is is a DEMONSTRATED crosswind, but even though it may not be limiting it doesn't automatically guarantee that the aeroplane CAN operate in stronger crosswinds. Sure, with common types like Cessnas, there will be plenty of people who will say they have operated the equipment in stronger crosswinds than the POH states but once you are outside the limits in the book you're going to have to explain why.
You're right that is is a DEMONSTRATED crosswind, but even though it may not be limiting it doesn't automatically guarantee that the aeroplane CAN operate in stronger crosswinds. Sure, with common types like Cessnas, there will be plenty of people who will say they have operated the equipment in stronger crosswinds than the POH states but once you are outside the limits in the book you're going to have to explain why.
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I think what papi-74 is trying to say is that if you fly outside the flight manual limits you are not insured, since the C of A is automatically invalid and the flight is illegal, so you are notinsured. If the limitations section states an absolute limit, then he is correct, but some only say that the xwind limits mentioned have been demonstrated - however, if they are actually in the limitations section, I wouldnt want to argue the point in court
Phil
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...and in any case, as commander you will have taken a look at the weather prior to departure and as such will be aware of the strength and direction of the wind at your destination and your alternates. You will also have a view on the risks of the weather situation changing and be in a reasonable position to avoid having to land your machine outside its limits!
As such, if you check the ATIS and it is outside limits, then you should be in a poistion to go somewhere else with a runway that is more into wind.
As such, if you check the ATIS and it is outside limits, then you should be in a poistion to go somewhere else with a runway that is more into wind.
Why do it if it's not fun?
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Hufty and Papi-74, that is complete rubbish.
I agree that if the manufacturer sets a cross-wind limit, you must stick to it or you will not be insured. Also, if you fly a club aircraft, you must comply with any limits in the club's Flying Order Book, or you will not be insured.
My club's FOB gives no cross-wind limit for holders of a CPL or higher license.
The POH for the aircraft I fly the most only gives a demonstrated crosswind. What's more, the manual explicitly states that this is not a limit!!! I'm not sure how much clearer I can make it.
FFF
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I agree that if the manufacturer sets a cross-wind limit, you must stick to it or you will not be insured. Also, if you fly a club aircraft, you must comply with any limits in the club's Flying Order Book, or you will not be insured.
My club's FOB gives no cross-wind limit for holders of a CPL or higher license.
The POH for the aircraft I fly the most only gives a demonstrated crosswind. What's more, the manual explicitly states that this is not a limit!!! I'm not sure how much clearer I can make it.
FFF
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Navoff,
I know that 12kts isnt bad but i wouldnt feel happy going flying in something much stronger that that. I dont care what the a/c can deal with, its what i can deal with that i care about. As a low hours PPL, i just wouldnt like to be landing in something above 12kts (ish) up until i had abit more experience behind me.
I know that 12kts isnt bad but i wouldnt feel happy going flying in something much stronger that that. I dont care what the a/c can deal with, its what i can deal with that i care about. As a low hours PPL, i just wouldnt like to be landing in something above 12kts (ish) up until i had abit more experience behind me.
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Flyingforfun,
I am not sure what you are driving at. You say that you agree with both Hufty and myself and then say we are talking rubbish. Forgive me, but which is it chap.
My comment was to the original thread about landings and the best way to achieve this safely, which I think I did. I did also state that it is more than possible to fly beyond the aircrafts crosswind limit (demonstrated). I also mentioned the gust limit of which I bet most of you don't know for you aircraft, demonstrated or recommended, but I am sure you will find out and put in a slating reply (I hope you do...it's funny).
I also mentioned that you won't be insured. Ever tried to cross hire an aircraft on a windy day....9/10 won't give you the aircraft. The cert. of ins. may not mention that you have to stay within the demonstrated xwc, but the first thing the insurance companies will do is contact ATC, be it at the airfield or the MET office and get the wx. Do you really think that they will pay if you have been a bit keen to prove what a great pilot you are, and do you really think that ATC won't file a repport to the CAA if you hit one of the runway side lights or Jonny at the hold.....they will.
How clever will you feel then?
What if it goes really wrong and the gear decides that it isn't in a good mood and buckles....and it will one day. If the gear doesn't buckle, you could always spin it in when cross controlling. I do speak from experience, but luckely I had enough power available and rudder authority to recover (during my Bulldog days). With a full tank of fuel you may have a few seconds to get yourself and the no longer impressed pax out before you painfully burn to death. There is always tomorrow!
For Christ sake, it is illegal to depart your airfield if the fc at your destination is out of limits. Fly somewhere else or fly in the morning / late evening when it is calmer (usually). You have a duty of care. What do you gain if you regularly play with fire (ok the odd approach where you feel the conditions to your commital height, 200' ish), respect.....a well done.....a wow maybe i'll try it then.....I hope not. More like a frown and noone will trust you to make a sound decision when it matters.
I am not sure what you are driving at. You say that you agree with both Hufty and myself and then say we are talking rubbish. Forgive me, but which is it chap.
My comment was to the original thread about landings and the best way to achieve this safely, which I think I did. I did also state that it is more than possible to fly beyond the aircrafts crosswind limit (demonstrated). I also mentioned the gust limit of which I bet most of you don't know for you aircraft, demonstrated or recommended, but I am sure you will find out and put in a slating reply (I hope you do...it's funny).
I also mentioned that you won't be insured. Ever tried to cross hire an aircraft on a windy day....9/10 won't give you the aircraft. The cert. of ins. may not mention that you have to stay within the demonstrated xwc, but the first thing the insurance companies will do is contact ATC, be it at the airfield or the MET office and get the wx. Do you really think that they will pay if you have been a bit keen to prove what a great pilot you are, and do you really think that ATC won't file a repport to the CAA if you hit one of the runway side lights or Jonny at the hold.....they will.
How clever will you feel then?
What if it goes really wrong and the gear decides that it isn't in a good mood and buckles....and it will one day. If the gear doesn't buckle, you could always spin it in when cross controlling. I do speak from experience, but luckely I had enough power available and rudder authority to recover (during my Bulldog days). With a full tank of fuel you may have a few seconds to get yourself and the no longer impressed pax out before you painfully burn to death. There is always tomorrow!
For Christ sake, it is illegal to depart your airfield if the fc at your destination is out of limits. Fly somewhere else or fly in the morning / late evening when it is calmer (usually). You have a duty of care. What do you gain if you regularly play with fire (ok the odd approach where you feel the conditions to your commital height, 200' ish), respect.....a well done.....a wow maybe i'll try it then.....I hope not. More like a frown and noone will trust you to make a sound decision when it matters.
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...yes it is!
FFF is right though - if it states explicitly that it isn't a limit then technically you can operate the machine in any crosswind that it is able to deal with. My point is that you need to be able to justify everything you do. If you're in court trying to argue that you had the skills to do something that the factory test pilot wasn't able to demonstrate then you're going to need to be confident in your argument!
FFF is right though - if it states explicitly that it isn't a limit then technically you can operate the machine in any crosswind that it is able to deal with. My point is that you need to be able to justify everything you do. If you're in court trying to argue that you had the skills to do something that the factory test pilot wasn't able to demonstrate then you're going to need to be confident in your argument!
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My personal and limited experience suggests this whole demonstrated limit business is somewhat inconsistent.
The US aircraft do seem to be consertative in this respect. I've had the oportunity to land both the AA5 and Arrow outside of the demonstrated limit in about 20kts of crosswind component and it was clearly within the limits of said aeroplanes. Indeed, the French types seem to have quite high limits, the Robins, Socatas and Wassmers with demonstrated limits of 25kts, which I imagine would be more challenging than exceeding the demonstrated limit in the Arrow.
On a point of possible interest, the Cub has a demonstrated limit of 10kts and frankly I find it challenging landing it with a component of only 8kts. The Super Cub a demonstrated limit of 12kts and yet again about 8kts was challenging enough for me.
The US aircraft do seem to be consertative in this respect. I've had the oportunity to land both the AA5 and Arrow outside of the demonstrated limit in about 20kts of crosswind component and it was clearly within the limits of said aeroplanes. Indeed, the French types seem to have quite high limits, the Robins, Socatas and Wassmers with demonstrated limits of 25kts, which I imagine would be more challenging than exceeding the demonstrated limit in the Arrow.
On a point of possible interest, the Cub has a demonstrated limit of 10kts and frankly I find it challenging landing it with a component of only 8kts. The Super Cub a demonstrated limit of 12kts and yet again about 8kts was challenging enough for me.