Fleet grounded at 7kts??
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On the subject of rotary cross wind is, as has already been suggested, an issue. This is particularly the case if you have to fit in with the f/w circuit traffic or there are obstructions around the landing are preventing you from approaching into wind. Under these circumstances you are crabbing with the crab angle increasing as you slow down. Side cyclic limits are a factor but so is the tail rotor. This is one area where the R22 seems better than most. Getting onto the ground is not normally a great problem if you do it right. The challenge is then hover taxiing back to dispersal. Try this in something like a Brantly with limited tail rotor effectiveness and it become an interesting exercise once you get past 15 knots or so - particularly in confined areas.
I once had an "interesting" time in a B206 (JetRanger) in gusty conditions - with a gusty crosswind from the right, in the hover, when the gust disappeared.
The bootful of left pedal I had (keeping the aircraft pointing where I wanted it, against the crosswind) meant that the gust dissipation led to an instant 90 degree turn to the left before I could catch it (ending up pointing downwind and descending in the process) - so it's not just the arrival of a gust which can cause problems, it's their departure too, and not just for helicopters, I'm sure.
But generally we have it easier that our f/w compatriots because we don't have to land then stop, we stop then land, so there are more options on what we do below 50 or 60 knots.
The bootful of left pedal I had (keeping the aircraft pointing where I wanted it, against the crosswind) meant that the gust dissipation led to an instant 90 degree turn to the left before I could catch it (ending up pointing downwind and descending in the process) - so it's not just the arrival of a gust which can cause problems, it's their departure too, and not just for helicopters, I'm sure.
But generally we have it easier that our f/w compatriots because we don't have to land then stop, we stop then land, so there are more options on what we do below 50 or 60 knots.
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Hi Whirlly .. am I missing something ? is the offset not 70 degrees? If so would that not make 100% of the crosswind and officially beyond the limits of a 150? Anyway I have heard of one airfield |(2 people swear this is true) training in 40 knot plus crosswinds?!! The CFI was 35,000 hours but I find 25 knots very demanding and have 500 hours in 150s but even so rermind myself I'm still a relative novice and leave the heroics for more able pilots.
- Tim
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A 20kt crosswind is not difficult.
An excerpt from my 172 flight manual:
The maximum allowable crosswind velocity is dependent upon pilot capability as well as aircraft limitations. With "average" pilot technique direct crosswinds of 37km/h - 20kts can be handled with safety.
There is no demonstrated crosswind at all in the POH. Flying out of a strip that only has one usable runway most of the winter I often encounter days where the crosswind is much higher than 20kts straight across. Currency and practice count in this situation. Landing at night at our place with these winds is a lot more bum clenching!!!
An excerpt from my 172 flight manual:
The maximum allowable crosswind velocity is dependent upon pilot capability as well as aircraft limitations. With "average" pilot technique direct crosswinds of 37km/h - 20kts can be handled with safety.
There is no demonstrated crosswind at all in the POH. Flying out of a strip that only has one usable runway most of the winter I often encounter days where the crosswind is much higher than 20kts straight across. Currency and practice count in this situation. Landing at night at our place with these winds is a lot more bum clenching!!!
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The other thing is that the reported x/w is measured at the top of quite a tall pole; 10m I think.
So the actual xw seen by the aircraft when about to touch down is a lot less than that reported.
This is why the aircraft normally straightens out by itself, to a large degree or sometimes even all the way to the runway heading, during the flare. Unfortunately, the inertia in yaw eggagerates this effect and one finds that a lot of rudder is needed pretty quickly.
A 20kt genuine x/w is not easy to land in. One needs loads of rudder, loads of opposite aileron, and courage. This would correspond to something like 30kt reported x/w figure.
So the actual xw seen by the aircraft when about to touch down is a lot less than that reported.
This is why the aircraft normally straightens out by itself, to a large degree or sometimes even all the way to the runway heading, during the flare. Unfortunately, the inertia in yaw eggagerates this effect and one finds that a lot of rudder is needed pretty quickly.
A 20kt genuine x/w is not easy to land in. One needs loads of rudder, loads of opposite aileron, and courage. This would correspond to something like 30kt reported x/w figure.
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Interesting point about the wind being measured at the top of a pole. Yesterday landing at Cambridge in a C152, the crosswind was gusty and around 20kts. I stuck to it down finals but was 90% sure I was going to have to go around, but in the last 20ft or so things calmed down considerably and in the end it was fine. A wind measured at the top of a pole would have suggested it wasn't possible to land a C152 under those conditions.
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Yesterday landing at Cambridge in a C152, the crosswind was gusty and around 20kts. I stuck to it down finals but was 90% sure I was going to have to go around, but in the last 20ft or so things calmed down considerably
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Thankfully the friend I was meeting is a pilot (big stuff) so I didn't feel under any pressure to land if it wasn't safe. He told me afterwards that he'd decided if I went around twice, he would be off home (as would I!)
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Think in terms of "boundary layer". There is the wind speed, and closer to the ground, the earth's boundary layer will begin to have an effect, which will be to slow the wind. Of course, many factors will affect this, so you can't usually quantify these effects. However, they will result in some wind speed reduction very close to the surface. Beware that any topographic "funneling" could cause an opposite effect, but generally, airports are not found where a crosswind funneling effect is fa big problem.
Also, as the aircraft comes into ground effect, the flight controls will be just a bit more effective. Thus, if you can maintain the runway heading with precision down final approach, chances are good that it'll become more easy close to the surface.
Also, as the aircraft comes into ground effect, the flight controls will be just a bit more effective. Thus, if you can maintain the runway heading with precision down final approach, chances are good that it'll become more easy close to the surface.
As instructor I would like to comment from the other side of the desk.
The OP did not specify who he was talking to when he was refused the chance to fly. Dispatch staff tend to be low experienced individuals and thus are given little descretion. A discussion with the CFI may had generated an exception for you.
On the other hand and at the risk of being rude, maybe they did not think you were good enough. I see discredition applied all time at school where I help out at. Sadly a significant proportion of the rental Pilots only seem to be interested in maintaining their skills to the absolute bare minimum. These pilots don't get the keys if there is any doubt about the conditions. However I have watched a relatively low time PPL get dispatched to a shortish field with a 15 kt 90 degree crosswind. There was not the slightest doubt in any of our minds that he would have any difficulty handling the conditions.
The OP did not specify who he was talking to when he was refused the chance to fly. Dispatch staff tend to be low experienced individuals and thus are given little descretion. A discussion with the CFI may had generated an exception for you.
On the other hand and at the risk of being rude, maybe they did not think you were good enough. I see discredition applied all time at school where I help out at. Sadly a significant proportion of the rental Pilots only seem to be interested in maintaining their skills to the absolute bare minimum. These pilots don't get the keys if there is any doubt about the conditions. However I have watched a relatively low time PPL get dispatched to a shortish field with a 15 kt 90 degree crosswind. There was not the slightest doubt in any of our minds that he would have any difficulty handling the conditions.
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So much dispute, so little facts.
First, there is a big difference in POHs from different built years. The older POHs of 150 and 172 state only a demonstrated crosswind up to which is has been shown to land safely for an average pilot. Later POH set a clear limit, do not exceed certain crosswind. I remember the SP I took training had a clear limit of, I think it was 17 knots, but the old one I am flying now has this legendary demonstrated sentence instead. Same is true for 152s - the "ordinary" ones have a limit, but the F Aerobats have no sentence limiting crosswind. So, it depends on the correct POH wether it is legal to land and within stated operational limits or not - in the end.
Then we have the question where to fly. I dont know the airfield in question, but had quite some fields where certain wind direction where simply unflyable due to obstacle turbulence.
Last and most important - upon what pilot we are talking? Low time students I would not force into strong crosswind, while high time students should go up to the limits of POH to get the feeling for real crosswind. But all depends on the guesstimate of the FI and his knowledge of the student. Pilots will encounter it later on and it is always better to do with an instructor first ... Or are we talking charter? Then it gets obscure as the flight safety is solely on the discretion of the pilot. And yes, I did landings with up to 35G40 knots crosswind with a C172, but after this I knew I could do if needed, but will do much to avoid it.
First, there is a big difference in POHs from different built years. The older POHs of 150 and 172 state only a demonstrated crosswind up to which is has been shown to land safely for an average pilot. Later POH set a clear limit, do not exceed certain crosswind. I remember the SP I took training had a clear limit of, I think it was 17 knots, but the old one I am flying now has this legendary demonstrated sentence instead. Same is true for 152s - the "ordinary" ones have a limit, but the F Aerobats have no sentence limiting crosswind. So, it depends on the correct POH wether it is legal to land and within stated operational limits or not - in the end.
Then we have the question where to fly. I dont know the airfield in question, but had quite some fields where certain wind direction where simply unflyable due to obstacle turbulence.
Last and most important - upon what pilot we are talking? Low time students I would not force into strong crosswind, while high time students should go up to the limits of POH to get the feeling for real crosswind. But all depends on the guesstimate of the FI and his knowledge of the student. Pilots will encounter it later on and it is always better to do with an instructor first ... Or are we talking charter? Then it gets obscure as the flight safety is solely on the discretion of the pilot. And yes, I did landings with up to 35G40 knots crosswind with a C172, but after this I knew I could do if needed, but will do much to avoid it.
And yes, I did landings with up to 35G40 knots crosswind with a C172,
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I remember the SP I took training had a clear limit of, I think it was 17 knots, but the old one I am flying now has this legendary demonstrated sentence instead. Same is true for 152s - the "ordinary" ones have a limit, but the F Aerobats have no sentence limiting crosswind. So, it depends on the correct POH wether it is legal to land and within stated operational limits or not - in the end.
Unless the crosswind "limitation" is specified in Section 2, limitations (or the earlier format equivalent), there is no limitation. There is a stated demonstrated capability, that is not legally limiting. The pilot may attempt a landing in as great a crosswind as they choose, and be legal.
The prevailing design requirement reads:
Sec. 23.233
Directional stability and control.
(a) There may be no uncontrollable ground or water looping tendency in 90 degree cross winds, up to a wind velocity of 0.2 VS0, at any speed at which the airplane may be expected to be operated on the ground or water.
(b) A landplane must be satisfactorily controllable, without exceptional piloting skill or alertness, in power-off landings at normal landing speed, without using brakes or engine power to maintain a straight path.
(c) The airplane must have adequate directional control during taxiing.
Directional stability and control.
(a) There may be no uncontrollable ground or water looping tendency in 90 degree cross winds, up to a wind velocity of 0.2 VS0, at any speed at which the airplane may be expected to be operated on the ground or water.
(b) A landplane must be satisfactorily controllable, without exceptional piloting skill or alertness, in power-off landings at normal landing speed, without using brakes or engine power to maintain a straight path.
(c) The airplane must have adequate directional control during taxiing.
It is also noteworthy that the design requirements for limitations do not mention crosswinds at all - there is no requirement to state a crosswind "limitation".
Sec. 23.1583
Operating limitations.
(a) Airspeed limitations. Information necessary for the marking of the airspeed limits on the
indicator as required in Sec. 23.1545 must be furnished, including VA and VLO. The significance of each limitation and of the color coding must be explained.
(b) Powerplant limitations. Information must be furnished to explain the powerplant limitations and to allow marking the instruments under Sec. 23.1549.
(c) Weight. The airplane flight manual must include--
(1) The maximum weight;
(2) The empty weight and center of gravity location;
(3) The useful load; and
(4) The composition of the useful load, including the total weight of fuel and oil with full tanks.
(d) Load distribution. The established center of gravity limits must be furnished. If the available loading space is adequately placarded or arranged so that no reasonable distribution of the useful load listed in paragraph (c) of this section will result in a center of gravity outside of the stated limits, the Airplane Flight Manual (where required) need not include any information other than the statement of center of gravity limits. In other cases, the manual must include enough information to indicate loading combinations that will keep the center of gravity within established limits.
(e) Maneuvers . The following authorized maneuvers, appropriate airspeed limitations, and unauthorized maneuvers must be furnished as prescribed in this section.
(1) Normal category airplanes. For normal category airplanes, acrobatic maneuvers, including spins, are unauthorized. If the airplane has been shown to be "characteristically incapable of spinning" under Sec. 23.221(d), a statement to this effect must be entered. Other normal category airplanes must be placarded against spins.
(2) Utility category airplanes. For utility category airplanes, authorized maneuvers shown in the type flight tests must be furnished, together with recommended entry speeds. No other maneuver is authorized. If the airplane has been shown to be "characteristically incapable of spinning" under Sec. 23.221(d), a statement to this effect must be entered.
(3) Acrobatic category airplanes. For acrobatic category airplanes, the approved flight maneuvers shown in the type flight tests must be included, together with recommended entry speeds. A placard listing the use of the controls required to recover from spinning maneuvers must be in the cockpit.
(f) Flight load factor. The positive limit load factors, in g's, must be furnished.
(g) Flight crew. If a flight crew of more than one is required for safety, the number and functions of the minimum flight crew must be furnished.
(h) Kinds of operation. The kinds of operation (such as VFR, IFR, day, or night) in which the airplane may or may not be used, and the meteorological conditions under which it may or may not be used, must be furnished. Any installed equipment that affects any operating limitation must be listed and identified as to operational function.
(i) If the unusable fuel supply in any tank exceeds five percent of the tank capacity, or one gallon, whichever is greater, information, showing that the fuel remaining in the tank when the quantity indicator reads "zero" cannot be safely used in flight, must be furnished. This information must be in the Airplane Flight Manual (if provided) and on a placard.
Operating limitations.
(a) Airspeed limitations. Information necessary for the marking of the airspeed limits on the
indicator as required in Sec. 23.1545 must be furnished, including VA and VLO. The significance of each limitation and of the color coding must be explained.
(b) Powerplant limitations. Information must be furnished to explain the powerplant limitations and to allow marking the instruments under Sec. 23.1549.
(c) Weight. The airplane flight manual must include--
(1) The maximum weight;
(2) The empty weight and center of gravity location;
(3) The useful load; and
(4) The composition of the useful load, including the total weight of fuel and oil with full tanks.
(d) Load distribution. The established center of gravity limits must be furnished. If the available loading space is adequately placarded or arranged so that no reasonable distribution of the useful load listed in paragraph (c) of this section will result in a center of gravity outside of the stated limits, the Airplane Flight Manual (where required) need not include any information other than the statement of center of gravity limits. In other cases, the manual must include enough information to indicate loading combinations that will keep the center of gravity within established limits.
(e) Maneuvers . The following authorized maneuvers, appropriate airspeed limitations, and unauthorized maneuvers must be furnished as prescribed in this section.
(1) Normal category airplanes. For normal category airplanes, acrobatic maneuvers, including spins, are unauthorized. If the airplane has been shown to be "characteristically incapable of spinning" under Sec. 23.221(d), a statement to this effect must be entered. Other normal category airplanes must be placarded against spins.
(2) Utility category airplanes. For utility category airplanes, authorized maneuvers shown in the type flight tests must be furnished, together with recommended entry speeds. No other maneuver is authorized. If the airplane has been shown to be "characteristically incapable of spinning" under Sec. 23.221(d), a statement to this effect must be entered.
(3) Acrobatic category airplanes. For acrobatic category airplanes, the approved flight maneuvers shown in the type flight tests must be included, together with recommended entry speeds. A placard listing the use of the controls required to recover from spinning maneuvers must be in the cockpit.
(f) Flight load factor. The positive limit load factors, in g's, must be furnished.
(g) Flight crew. If a flight crew of more than one is required for safety, the number and functions of the minimum flight crew must be furnished.
(h) Kinds of operation. The kinds of operation (such as VFR, IFR, day, or night) in which the airplane may or may not be used, and the meteorological conditions under which it may or may not be used, must be furnished. Any installed equipment that affects any operating limitation must be listed and identified as to operational function.
(i) If the unusable fuel supply in any tank exceeds five percent of the tank capacity, or one gallon, whichever is greater, information, showing that the fuel remaining in the tank when the quantity indicator reads "zero" cannot be safely used in flight, must be furnished. This information must be in the Airplane Flight Manual (if provided) and on a placard.
Yes, mechanical turbulence can greatly affect the capability of an aircraft and pilot, and acting as a crosswind, even more.
I have taken off my 150 in 37G43 knots at a 45 degree angle for an emergency flight. I did not attempt to land back on the same runway, I selected a different aerodrome, with the runway right into the wind.
Sec. 23.233
Directional stability and control.
(a) There may be no uncontrollable ground or water looping tendency in 90 degree cross winds, up to a wind velocity of 0.2 VS0,
Directional stability and control.
(a) There may be no uncontrollable ground or water looping tendency in 90 degree cross winds, up to a wind velocity of 0.2 VS0,
Which country's regulations are you quoting?
That 0.2 Vso value looks like the reason for the ludicrously-low demonstrated cross-wind value of my club's DG-1000S:
The demonstrated crosswind velocity is 15 km/h (8 kts.) according to the airworthiness requirements.
Due to the towhook position being in the middle of the fuselage and the excellent effectiveness of the ailerons and rudder, the possibility of wing dropping or ground loops, even on a slowly accelerating aerotow is reduced. Take-off with strong crosswind is possible.
Since tmmorris resurrected an 8 year old thread it is unlikely the OP will see this. However, another interpretation is that this could have been his first night circuit session on a short narrow runway (it was night after all) in which case the decision was wise.................
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Sorry for the resurrection... I was looking for the sort of thing Step Turn posted, because I'd read the POH carefully to see the wording on the 'limit'. Thanks for that!