20 November, 2009

How to Work Out a Cross Wind Component in Seconds When on Final Approach to Land

By Chris Puddy

When coming in to land it is often difficult to work out the cross wind component quickly. There are 2 quick methods I know to be able to do this and when you understand them choose the one that suits you best.

The first one is known as the clock code and with it you assume that any wind that is more than 60 degrees off the runway heading is a full strength cross wind. So if landing on say runway 27 which is 270 degrees from North, then if the wind direction is less than 210 or more than 330 degrees, whatever the strength is it is regarded as full cross wind. So if the wind is say 200 at 15 knots then it is a 15 knots cross wind.

Now to work out how much of a cross wind there is between these 60 degrees either side of the runway heading you imagine that the number of degrees off the heading are the numbers of minutes round a clock face. Then imagine how far round the clock face that is, and that proportion round the clock face is the proportion of the wind strength.

So if the wind is 20 degrees off the heading, say for example 290 at 30 knots, then 20 minutes is one third of the way round the clock face, so the cross wind component is one third of 30 knots which is 10 knots.

If the runway was 03 which is 030 degrees, and the wind was 070 at 20 knots, this is 40 degrees off, and 40 minutes round the clock face is nearly nearly three quarters of the way round the clock face so the cross wind is three quarters of 20 or 15 knots.

As wind constantly varies in strength and direction, then you do not need to be highly accurate with your calculation. If the wind is roughly 30 degrees off, it is half strength so roughly half the wind strength is the cross wind component. 45 degrees off is 3/4 of the strength of the wind and 60 degrees or more full strength.

Another easy way to work out cross wind and head wind component is using this simple mathematical formula.

For calculating cross wind. If the wind it 30 degrees off the nose it is.5 the wind strength, 45 degrees off.7 the wind strength, 60 degrees off it is.9 the wind strength, and if 90 degrees of then obviously it is full strength. This applies on cross country flights, or for working out the cross wind when coming in to land.

If for example when coming in to land the wind is 60 degrees off the runway heading it is.9 times the wind strength, so using simple arithmatic on a 20 knot wind just multiply 9 by 2 which is 18 knots. For a wind of 30 knots and 45 degrees off the runway heading the calculation is 3 X 7 which is 21 cross wind component. If like me you learned your multipliction tables as a child, this is easy.

If you reverse the formula, you can use it to work out head wind or tail wind component as well. So if the wind is directly towards you, it is full strength, if 30 degrees off it is.9 of full strength, 45 degrees off.7 of full strength, and 60 degrees off it will be half strength.

If it is 90 degrees off then there is no head or tail wind component. However bear in mind that any strong wind will be affecting the aircraft by drifting and turning into wind will in effect mean that you have to fly a longer track than a straight line so it will slow you down a little bit.

If the wind is coming from behind you, then the same proportions can be applied to work out the tail wind component, so if it is 30 degrees off your tail, it is.9 of the strength of the wind and so on.

For working out a diversion, you can apply this percentage to your airspeed to get the groundspeed, and then to work out drift interpolate the following formula as well. The formula is that at 120 knots airspeed, half the cross wind component is drift. So if you are flying at 90 knots then your drift would be 25% more than half the drift.

This method can be used to quickly calculate heading and groundspeed if a diversion is necessary, or if you want to check your calculations after using a computer to plan your journey.


Chris Puddy has been flying since 1965 and had had a variety of flying since then, mostly on light aircraft, and much of it single crew with no autopilot with many landings. He also has over 2500 hours instructing, and his varied experience is a huge benefit to his students especially as much of his flying was single crew without an autopilot.


Chris is CFI of the Cotswold Flying School at Kemble in the UK.


Article Source: http://EzineArticles.com/?expert=Chris_Puddy
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09 November, 2009

Let's redesign the Artifical Horizon, shall we?

New research has indicated that the Artificial Horizon which was introduced in 1927 to allow pilots to fly safely in cloud, is not actually the best design. Test carried out by cockpit ergonomics researcher Donough Wilson of Coventry University indicated that 92% of pilots would make a fatal error in recovering a plane shown in a specific position due to the limitations of the AH.

Look at this diagram


I'm confused. Is the plane on the left banking to the port or the starboard. If it is banking to port then why is the AH showing a turn to starboard? Or am I misreading this (which is - after all - the premise of the research)? I suspect that's the whole point of this: at a certain point a starboad turn will end up being indicated as a turn to port. Recovery from this would be to turn the plane to starboard thereby increasing the turn and putting the plane into a potential spin.

The new design works by  keeping the horizon level and indicating the angle of bank of the aircraft by turning a display showing the heading. In the diagram above the plane is turning on a heading of 204 degrees. The benefit of this is that as you are turning the numbers will increase/decrease depending on your direction of turn. This is an additional safety indicator.

My problem is that the new design isn't quite as 'useful'. Is the plane in level flight but turning? Or is it pitching down slightly? If you are used to the design on the left you would assume that the plane was pitching down because the numbers appear to be below the 'horizon'. However in reality there is no pitch indication on this instrument. Not at the moment anyway. That's planned for the future.

There is concern about adopting such a radical design change. Phil Hosey of the International Federation of Airworthiness in East Grinstead, UK says "This would be like changing the side of the road a country drives on. And the big question is how long would it take existing pilots to train on this."

Indeed.

However there could be a potential us for remotely piloted vehicles such as the military UAV's. Any intrument which can give a remote pilot more spatial awareness would be better.

Original article and graphic courtesy of New Scientist

05 November, 2009

Tips and Tricks For Private Pilots - Check Ride Guides

By Bruce Hogan

Anytime one is completing a practical test in any subject the attitude of the examiner plays a part in how comfortable and confident you feel. Of course you are going to feel some form of intimidation, but make every effort to put this aside as it will interfere with your capabilities.

Completing your Private Pilot Check ride is a perfect example of the above scenario. This is your final practical test before achieving your Private Pilot License. You must remember that the examiner has a job to do. He/she must determine that you are knowledgeable enough and capable of flying a plane on your own. There is a standard form that the examiner must follow but some will add a few twists of their own to see how you react. They go a little beyond the classic textbook knowledge.

A favored trick of some examiners is the pencil fallacy. Here they will drop their pencil at some point of time during your flying. Most often, it will occur when you are engaged in performing a task that requires your undivided attention such as doing a turn. Your first instinct is to want to impress the examiner, so you will immediately try to retrieve the pencil taking your attention away from your maneuver. This act of kindness on your part could cause you the loss of the chance to obtain your license. In other word a failing mark. Be one-step ahead of these types of ploys. Keep extra pencils on your kneeboard. Then simply tell the examiner you cannot reach their pen as you must concentrate on what you are doing, but in fact, you do have an extra one.

Always be prepared for the unexpected. Dead batteries are one of the most common mishaps. Let's assume you are being rerouted to another airport and your E6B that you rely so heavily on is suddenly flat. If you carry a good supply of extra batteries with you then there is not going to be a problem. If you don't then you have to rely on the wheel that you have thought about since your initial training. Talk about extra stress this is it. The last thing you need is any more stress at this particular time.

There are not only instances where deviating from your concentration could be dangerous they could also be embarrassing. You can imagine how you would feel if you were in the take off mode only to discover that, you hadn't removed the tie down rope? After all, isn't this something you should have completed in your pre flight? The lesson to be learned here is taking nothing for granted and check everything.

The purpose of this test is to show you are capable of being the pilot in command. This includes viewing your examiner as your passenger. Ensure that your passenger has his seatbelt on. If you miss this simple step you could be missing your license. Don't forget about the pre flight briefing that is to be given your passenger as well. You are ultimately responsible for the safety of your passenger regardless if he happens to be the examiner. Also, remember to do your break check at your takeoff. You have to show that you are considering the flight as a whole. You need to know that you can land.

You must always be prepared. This means that if the examiner were to tell you that an engine was out you would have to be prepared for an emergency landing. In this case, you need to be constantly aware of your surroundings and always know the possible places you could put your plane down safely if you had to do so.

These are just a few of the unforeseen circumstances your examiner could put in your path. Just be prepared for anything.


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