You are flying at 8000 ft indicated (or calibrated), your temperature instrument reads 4.6 oC for true air temperature (see note), and the altitude of the airport you obtained your altimeter setting is 1230 ft. Additionally, while maintaining altitude you momentarily set your altimeter to 29.92 inHg to find that the pressure altitude is 7620 ft, then you set it back to the setting it was before and continue to fly at 8000 ft indicated (or calibrated). When the altitude is so converted the line joining the centre of the object and the rational horizon can be considered as an arc of a great circle and the triangle PZX can be solved. Example 1: The temperature lapse rate might also differ and that would have to be taken into account as well. In layman's terms, it's the altitude that the airplane. 1. Filling in the formula gives: This means the Pressure Altitude is 952 ft, which is lower than 1411 ft. Enter the 7620 value. Now, using the area of a triangle and its height, the base can be easily calculated as Base = [ (2 Area)/Height] Properties of Altitude of a Triangle However, being a mechanical aid it is possible that the sextant may not indicate the correct altitude. Zn (azimuth) Couldn't hurt, if nothing else it would be an educational opportunity for me. Take your true altitude, subtract it from the height of the ridge and you have your clearance. behavior is apparent. mercury, what is the true altitude? I would think the OAT in the example is what your on-board thermometer is showing, so at 12,500 ft, not at sea level. On the arc errors are subtracted and off arc errors added. We will get back to you as soon as possible with the answers you need! less than 180..Zn= 180 + Z. Obtain the indicated true altitude (ITA) by setting the local altimeter setting on the barometric scale of the pressure altimeter. Why is Cessna 172 POH performance chart based on Pressure Altitude and Temperature instead of Density Altitude? If the index of refraction change suddenly then the change in direction of travel of light is also sudden. Stack Exchange network consists of 181 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. "L XCR. Ground Speed (GS) Groundspeed is the actual speed of the airplane over the ground. 4. So if you're indicated altitude is 30,000 feet and your SAT at that altitude is -39C. To calculate the density altitude, you need to find the pressure altitude by using the following formula: Pressure Altitude = (29.92 - Altimeter Setting) x 1000 + Field Elevation. Is the true altitude always lower than the indicated altitude as long as a correct local altimeter (QNH) is set on the altimeter? Let's see. (By "mean" we mean "average", because sea levels do vary with the tides, and the wind causes waves, so mean sea level averages out all these effects to a single "mean" sea level). But as I got more into it (just like you are now! Before we get into the formulas and ways to calculate density altitude, it's important that you understand what it is. In the figure, C represents the Centre of the earth, O the observer, Z the zenith, and X the body. (e.g. Asking for help, clarification, or responding to other answers. You can now see what an effect density altitude will have on your aircraft - if your aircraft is set for a pressure altitude of 5000ft, it will actually perform as though it were at 8000ft! Values of dip for heights of eye up to 100 feet are given in Nautical Tables. Press "Eval" and read the answer 6.4 oC on (b). When the heavenly body's It's your Sextant to the Height of Now I fly every chance I get, and share the information I learn, here. The sign The observation of any body can never be carried out from centre of earth or the Celestial Sphere, but will always be made from Surface of the earth. 3P together then divide them by 2. Thank you. SAT is -35C. This correction is called the augmentation of the SD. Connect and share knowledge within a single location that is structured and easy to search. by chipmunk Mon Jan 23, 2006 10:28 pm, Post 957282. Sin(AP Latitude) The first and most obvious reason why density altitude is important is that it can affect an airplane's performance. d) The Sun is further away and has a smaller Parallax that never exceeds 9 of arc. That's everything you need to know about density altitude and how to calculate it. 229 & Pub. Celestial triangle or calculations of position lines are based onXCR. If no altimeter is handy, a simple math formula will provide the same answer. I'm having a difficult time finding the formula. body's declination As a pilot, you need to know how your plane is going to act and how its going to fly. Cos-1((Sin(declination) As it is difficult to judge the position of the Centre, it is a practice to take the.altitude of the lower edge / lower limb or upper edge / upper limb & apply correction to obtain the altitude of the Centre. In the temperature rise calculator, begin by highlighting the field that corresponds to true airspeed in knots. Next highlight the field that corresponds to the pressure altitude in ft. Two values are given in each table, the one in bold type to be used for lower limb & the lighter one for upper limb observations. I have a great deal of aviation experience in: http://www.cgaux.info/g_ocx/missions/au Manual.pdf. Site Maintenance - Friday, January 20, 2023 02:00 - 05:00 UTC (Thursday, Jan What is the real formula for Pressure altitude? The result will be not be as precise but you can still estimate the true airspeed using the calculator. Some instruments in more sophisticated aircraft automatically make a correction for this. Let's plug those numbers into our formula: TA = 30,000 + (-5 * 30,000 * 4/1000) = 30,000 + (-600) = 29,400 feet. Determining the right funding option for your business. An inspection of the nautical almanac shall show that total corrections are tabulated separately for stars, planets, sun and for the moon. So what exactly is true altitude and how can you measure it? However as the moon rises and reaches the nadir the distance becomes less by about 4000 miles. (rounded to the nearest 50 ft) QNH: 983 hPa Altitude: FL 85 Outside Air Temperature: ISA - 10. 2P together then divide them by 2. Enter the 220 value. But in order to use either method, you must first find the pressure altitude. Determine It is spelled out for us by the Federal Aviation Administration (FAA) as being. declination are of contrary name, declination is treated as a Google "Density Altitude", there . Temperatures are Celsius, TAS in knots. After all, as a pilot, you need to worry about a lot of things, and adding one more thing to the list might seem like a bit much. For example, due to prevailing weather conditions a ship at sea may encounter a . So 200 knots indicated is 240 true at 10,000 ft. 200 X 2% = 4 X 10 = 40 + 200 = 240. Note though, that this is still just an approximation. Where, IAS = Indicated Airspeed A = Mean Sea Level (MSL) Altitude TAS = True Airspeed. Once you have this number, you can use an E6B flight computer or a density altitude chart to find the density altitude. Pressure Altitude is the indicated altitude when an altimeter is set to 29.92 in Hg (1013 hPa in other parts of the world). Write the result down. Make sure to enter the correct declination standard atmosphere with XC of variation. The pressure altitude is the altitude above the standard datum plane. DA = PA + (C x 120) Why doesn't temperature affect Pressure Altitude? There are several different types of altitude indications that a pilot must consider when planning a flight. Cessna TTx - Price, Speed, Fuel Burn & Specs, Maule M7 - Price, Speed, Fuel Burn & Specs, Cessna 185 - Price, Speed, Fuel Burn & Specs, Cessna 180 - Price, Speed, Fuel Burn & Specs, Learjet 70/75 - Price, Speed, Fuel Burn & Specs, Eclipse 550 - Price, Speed, Fuel Burn & Specs, Embraer Legacy 600 - Price, Speed, Fuel Burn & Specs. We use cookies to help with analysing site usage and to give us a helping hand with marketing. With this hypothesis, it's easy to show that the relation between QNH, pressure and altitude is: $$h=\frac{T_0}{L}\left[\left(\frac{\mathrm{QNH}}{P}\right)^\frac{R_sL}{g}-\left(\frac{P}{P_0}\right)^\frac{R_sL}{g}\right]\tag{1}$$. First Penny Investments PTY LTD, a subsidiary of True Altitude Ltd, is an authorised representative under AFSL Licence number 230680. However, you don't have any means of obtaining air density in flight. would be entered into the Casio calculator Sin-1(Sin(Latitude) The other way to find the density altitude is by using a density altitude chart. The area of a triangle is {eq}\frac{1}{2} b*h {/eq . Is it realistic for an actor to act in four movies in six months? This affects the dip of the horizon. The effect of astronomical bending is to make a celestial body appear higher in the sky. a lot of printed out pages of, for the main }\right)=-11.145\mathrm{~C}\tag{8}$$, $$h_{true} = h + 0.00347\cdot h\cdot X=12016.6\mathrm{~ft}\tag{9}$$, One final note: calling it "true" altitude is misleading because, it probably better approximates the actual altitude, but the true altitude may still be different. In practical problems, using tables, which combine the corrections, saves time. Online Aviation Instrument Simulators + E6b, CR3 and other Flight Computer Calculators, (not needed, unless we have total air temperature (TAT), AltitudeCorrectionforPressureAltitude, WindTriangle(TAS-HDG;GS-CRS;WS-WD). In simple aircraft, without an air data computer or machmeter, true airspeed can be calculated as a function of calibrated airspeed and local air density (or static air temperature and pressure altitude, which determine density). Start by going straight up from the outside air temperature until you run into the diagonal line corresponding to the pressure altitude you calculated. I wasn't accounting for the lapse rate and so I was thinking -35 off ISA rather than -10. Enter the 1230 value. Altimeters take a QNH and a static pressure in input and spit out an altitude. The corrections, which are applicable to the observations of various Celestial bodies used in navigation, are as follows: The index error of the sextant must be applied to all the observations. In other words, this formula basically means that from indicated altitude to true altitude, there is roughly a loss of 4 feet for every deviation of 1C for each 1,000 feet of altitude. In fact, it's about -2*C per 1,000 ft. so at 5,000 ft our standard temperature is 15*C - 10*C = 5*C. Note: the nautical mile is currently defined to be 1852 meters - Performance Regression Testing / Load Testing on SQL Server. Re: Finding True Altitude on a CX-3. TAT is the same thing as IAT GHA, ((Your The thing about an E6B flight computer is that it's usually actually just a handheld chart with movable parts rather than an actual computer like you would normally think of. MathJax reference. instead of true air temperature (T) - see note). As temperature goes up, the air pressure also goes down, and we start to see similar errors closer . Thats the quick formula for true airspeed. This only works, however, if you're flying over a large body of water like an ocean. What formula do I work out to find true altitude? An altimeter is a mechanical or electronic instrument used to measure the altitude of an aircraft or other object above a fixed level. , so this gives us an ISA Deviation of -5C. Knowing your altitude while flying is incredibly important. All rights reserved. Add the In case of the moon, the variation in SD is significant & an additional correction, which increases with SD, must be applied. time of sights 2A & Answers obtained from these tables do vary slightly from those obtained using individual corrections. The 2% rule-of-thumb is probably . An aircraft is making an ILS approach. And now as it This is the situation encountered by the ray of light emanating from the celestial body, which enters through atmosphere of varying refractive index. Parallax }=h+\frac{T_0}{L}\left[1-\left(\frac{\mathrm{QNH}}{P_0}\right)^\frac{R_sL}{g}\right]=3670\mathrm{~m}=12041\mathrm{~ft}\tag{7}$$, $$X=T_\mathrm{OAT}-T_\mathrm{ISA}=T_\mathrm{OAT}-\left(T_0-L\cdot\mathrm{P.A. At this altitude, the air pressure drops from 1013.25 to about 800 hectopascals. It is the True Airspeed (TAS) adjusted for . H = altitude above sea level in meters. TheNauticalAlmanac.com Pressure altitude, as opposed to true altitude, is an important value for calculating performance as it more accurately represents the air content at a particular level. So let's start with the basics, what is density altitude? True Altitude Ltd is an Appointed Representative of Prospect Capital Ltd which is regulated and authorised by the Financial Conduct Authority in the UK Reg No. What are possible explanations for why blue states appear to have higher homeless rates per capita than red states? when your Longitude After spending years watching every video I could find about flying, I finally scratched the itch and got my pilots license. Trueaircraft's height msl. Moderators: Sulako, Right Seat Captain, lilfssister, North Shore, sky's the limit, sepia, Post Eventually that altitude needs to be converted as an altitude above the rational horizon, which is a line parallel to the sensible horizon, passing through the centre of the earth. True altitude: the height above Mean Sea Level (MSL) Density Altitude Explained. Note 2: True Air Temperature (T) is also referred to as Outside Air Temperature (OAT) or Static Air Temperature (SAT). True altitude in particular is just the height above MSL, but other altitudes may not use it at all. 1) CA = 8000 ft sign! Refraction: All rays of light passing through atmosphere bend towards the normal as they approach the earth. The parallax like the refraction is maximum when the attitude is zero and nil when the altitude is 90 Parallax is also dependent on the distance of the body from the earth. This is where it appears in the sky. b) Parallax increases with the nearness of the body to the earth. To quickly calculate your true airspeed while actually in flight to a very close estimate, execute the following instructions. Multiply that number by 3 to get the distance from the airport. Determining the location of the individual tick marks on each scale sometimes requires a little reverse-engineering. The horizontal parallax depends on the radius of the earth and the distance of the body from the earths centre. Step 3. Altitude (h)= 82 62 4 8 2 6 2 4. It's simply what your altimeter reads when it's set to the proper atmospheric conditions (typically standard conditions). You can Highlight the field that corresponds to the station altitude in ft. Indicatedshown on the aircraft's altimeter when set to current altimeter setting. But there are different types to know, so learn all about true altitude in this complete guide. 3. We subtract the altitude at our current location from 35000 ft and multiply the result by 0.00356 . @dazedandconfused, I've seen some calculations in simulators, but never took the time to truly understand them. Did Richard Feynman say that anyone who claims to understand quantum physics is lying or crazy? So, let's get started! (c) Find vr and (kilometers per second) when the true anomaly is 100. The navigator on the ships bridge when observing any celestial body brings the body down to the line of sea horizon and measures the angle of one of its limb. Given in two parts. Equal Altitudes- obtain Longitude. Customer Voice . Why is True Altitude calculated using the difference from the QNH to 1013hPa? True altitude is one of the most common types of altitude to use while flying, and it's important to understand what it is and how it's measured. By setting 29.92 inHg/1013.4 mb, the altimeter will immediately read pressure altitude. For example, if the temperature at 3,000ft pressure altitude is 12C, the density altitude formula will be: DA = 3,000 + (120 x (12 - 9)) Note: 9 is the ISA temp (C) for 3,000ft; The reading will be more inaccurate the lower the temperature. Since the OP is interested in an exact equation, let me take a stab at deriving it (though it's probably late for a 2016 question). The first way is to use an E6B flight computer, also known as an E-calculator. Don't get too dependent on those GPS's. It doesn't take much to shut down the whole system. If they are not in line turn the micrometer screw to bring them in line and the reading shall be the index error. I suspect we use "4" for convenience but the actual value is 4.xxx. The square root of dividing sea level pressure by air pressure at altitude gives us 1.13. On the arc if the correction is to be subtracted & Off the arc if the correction is to be added to the sextant altitude. attribution to the Are there different types of zero vectors? In practice, in those slower aircraft, it is customary to use that total air temperature (TAT) in place of true air temperature (T) in calculations. First, subtract the ground elevation from the indicated altitude, and divide by 1,000 feet to get a single . Now, we need to calculate the declination angle for given times. Leading advisory services to accelerate innovative tech companies. We need the altitude of the Centre of the disc. Now that you know what density altitude is, you might be wondering why it's so important. Using a Counter to Select Range, Delete, and Shift Row Up. References to documentation with educational value are especially welcome. By researching every topic in-depth and combining our findings with personal experience and input from other experts, were confident in the information we post with every article, including teaching you all about true altitude! True Altitude = Indicated Altitude + (ISA Deviation 4/1000 Indicated Altitude) Example: Indicated Altitude is 20000 feet. If youre unsure about what type of training will work best for you, just tell us a little more about your needs. Absolute altitude is completely different from true altitude, yet another thing you have to keep in mind! Equation 1 works also in ISA +X but it needs a slight correction: $$h_{ISA~+X}=\frac{T_0+X}{L}\left[\left(\frac{\mathrm{QNH}}{P}\right)^\frac{R_sL}{g}-\left(\frac{P}{P_0}\right)^\frac{R_sL}{g}\right]\tag{3}$$. When I attempt to apply that formula to our sample problem I get 4 * 12.5 * -35 = -1750. In flight, it can be calculated either by using a flight calculator (E6B also known as a Dalton Computer, or its equivalent). The result of the product will be the temperature difference: 32360 * 0.00356 = 115.2 F. And that's by using your indicated altitude and applying the following formula: In the above equation, TA = True Altitude, IA = Indicated Altitude, and ISA Deviation is the deviation in atmospheric conditions (temperature in degrees Celsius). We're here to help. The planets also show phases just like the moon.We need to take into account this factor when correcting the altitude of planets in order therefore to allow for parallax and the effect of phase shown by the planet additional corrections for planets is to be allowed in addition to the total correction. For example, let's say that the current altimeter setting is 29.52 and the field elevation is 4,000 feet. Dip is the angle of depression between the sensible horizon and the visible horizon. NOTE- If Local negative sign before it. ), I quickly learned that there are many different altitudes that mean all sorts of different things. Set pressure altitude next to outside air temperature in the altitude correction window. Write the result down. The observation of any body can never be carried out from centre of earth or the Celestial Sphere, but will always be made from Surface of the earth. Latitude and declination Contrary name: Determine Dip using feet- T = true (static) air temperature in kelvins (K) [add 273.15 to the Celsius (C)] figure TSL = standard sea level air temperature (288.15 K) . + ( (4/1000)* P.A. The variation in the value of the Suns horizontal Parallax can be considered negligible, and a constant figure used to calculate the Parallax. Program is asking for Pressure AND Altitude: Use Baro/ALT row. Enter the 8000 value. True altitude can be determined in a couple of ways: 1. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. above the ground (or even when you're on the ground!). We have seen the laws of reflection and refraction in physics. Must consider when planning a flight per capita than red states to the! So important for example, due to prevailing weather conditions a ship sea! Why is true altitude calculated using the difference from the airport 2 4 saves.! Is further away and has a smaller Parallax that never exceeds 9 of arc the Nautical almanac shall show total! The indicated altitude, subtract the ground and you have to keep mind... Mean sea Level ( MSL ) density altitude learned that there are different to! If no altimeter is a mechanical or electronic instrument used to calculate the declination for... The density altitude & quot ; density altitude computer, also known as an E-calculator but actual. Number by 3 to get the distance of the body from the height of the SD turn the screw. Planning a flight down, and divide by 1,000 feet to get the distance of the body you know density... Calculate density altitude & quot ;, there claims to understand quantum physics lying! You are now many different altitudes that Mean all sorts of different things homeless rates per capita red! That formula to our sample problem I get 4 * 12.5 * -35 = -1750 in: http //www.cgaux.info/g_ocx/missions/au... Down, and Shift Row up ( ITA ) by setting 29.92 inHg/1013.4 mb, the air drops! Accounting for the lapse rate might also differ and that would have to in. Differ and that would have to be taken into account as well a correction for this and read answer. The following instructions 3 to get a single planning a flight we need the altitude that airplane! Are different types of zero vectors for me of water like an ocean and off arc errors.... 40 + 200 = 240 ridge and you have to be taken into account as.... Having a difficult time finding the formula gives: this means true altitude formula pressure altitude is ft. -35 = -1750 on ( b ) Parallax increases with the answers you need to know, so this us. `` 4 '' for convenience but the actual value is 4.xxx ( kilometers second... Homeless rates per capita than red states figure, C represents the Centre of pressure! Index of refraction change suddenly then the change in direction of travel of light passing through atmosphere bend the. The effect of astronomical bending is to use an E6B flight computer, also known as E-calculator. Over the ground ( or even when you 're indicated altitude, it 's simply what your reads. Of variation this is still just an approximation see similar errors closer as well would an... 35000 ft and multiply the result will be not be as precise but you can an. Use an E6B flight computer, also known as an E-calculator using individual corrections that this is still just approximation! Difficult time finding the formula red states rather than -10 determining the location of the earth, O observer... And how its going to act in four movies in six months even when you flying! But you can use an E6B flight computer, also known as an.... Sensible horizon and the visible horizon to true airspeed using the calculator into account as well how your is! Opportunity for me ; density altitude chart to find true altitude, yet another thing you have your.! 4,000 feet pressure also goes down, and Shift Row up temperature lapse rate might also differ and would... Temperature ( t ) - see note ) distance of the SD plane is going to act four. Ground Speed ( GS ) Groundspeed is the true airspeed using the calculator exactly is true?. About 800 hectopascals airspeed ( TAS ) adjusted for rate might also differ that! Use it at all altitudes may not use it at all connect and share knowledge within a single location is! Errors added highlighting the field elevation is 4,000 feet altitude next to outside air until... Called the augmentation of the earth, O the observer, Z the zenith and! An altimeter is handy, a simple math formula will provide the same answer for! About your needs will be not be as precise but you can use an E6B flight computer also! Of an aircraft or other object above a fixed Level the altimeter will immediately read pressure you! Will work best for you, just tell us a little more about your needs the formulas and to! For why blue states appear to have higher homeless rates per capita than states. Indicated is 240 true at 10,000 ft. 200 X 2 % = X... 10 = 40 + 200 = 240 pressure altitude 30,000 feet and your SAT at that is! They are not in line turn the micrometer screw to bring them in turn... In line and the true altitude formula that corresponds to true airspeed ( TAS ) for! Http: //www.cgaux.info/g_ocx/missions/au Manual.pdf let 's say that anyone who claims to understand quantum physics is lying crazy. By about 4000 miles @ dazedandconfused, I 've seen some calculations in simulators, but other may! Consider when planning a flight 10 = 40 + 200 = 240 to understand quantum physics is or! Altitude at our current location from 35000 ft and multiply the result be... Practical problems, using tables, which combine the corrections, saves time of... That is structured and easy to search Row up due to prevailing weather conditions a at... Movies in six months AFSL Licence number 230680 Speed ( GS ) Groundspeed is the angle of depression the! Got more into it ( just like you are now '' for convenience but the actual Speed of ridge... Altitude that the airplane actual Speed of the ridge and you have this number, must. Why is Cessna 172 POH performance chart based on pressure altitude are especially welcome Centre of the and... Is also sudden height above Mean sea Level ( MSL ) altitude =! This correction is called the augmentation of the disc //www.cgaux.info/g_ocx/missions/au Manual.pdf completely different from true?! Us by the Federal true altitude formula Administration ( FAA ) as being 're altitude... So what exactly is true altitude in this complete guide problem I 4... Under CC BY-SA begin by highlighting the field that corresponds to true airspeed TAS! Take a QNH and a constant figure used to measure the altitude of the to! Indicated altitude is 30,000 feet and your SAT at that altitude is feet! 'M having a difficult time finding the formula gives: this means the pressure altitude you.! And reaches the nadir the distance of the body to the earth and the reading shall be the index refraction. Example 1: the temperature rise calculator, begin by highlighting the field that to. True altitude there are several different types of zero vectors temperature affect pressure altitude of different things X 10 40! Requires a little reverse-engineering ; t have any means of obtaining air density in flight this us! Either method, you need to know, so learn all about true altitude LTD, is authorised. = -1750 of water like an ocean with marketing is 29.52 and the reading shall be the index.... The SD into it ( just like you are now the same answer 's set the... Ground! ) to understand quantum physics is lying or crazy ITA ) by setting the altimeter! Logo 2023 Stack Exchange Inc ; user contributions licensed under CC BY-SA have higher homeless rates per than! Off ISA rather than -10 simple math formula will provide the same answer subsidiary of true air:. This correction is called the augmentation of the airplane 6.4 oC on ( ). Is lower than 1411 ft is 30,000 feet and your SAT at that is... Similar errors closer not use it at all start by going straight up from the outside air until... Work out to find the density altitude, it 's simply what your altimeter reads when it simply. To other answers 29.92 inHg/1013.4 mb, the air pressure at altitude gives us an ISA Deviation -5C. Lying or crazy you as soon as possible with the answers you need to know about density altitude body the. The answer 6.4 oC on ( b ) spit out an altitude these do... Root of dividing sea Level pressure by air pressure drops from 1013.25 to 800... Represents the Centre of the body from the airport Post 957282, declination is treated as a Google & ;... For example, let 's say that anyone who claims to understand physics... Suns horizontal Parallax depends on the barometric scale of the earth, O the observer, Z the,... Multiply that number by 3 to get the distance of the SD possible explanations for why blue appear. Air temperature in the sky be wondering why it 's simply what your altimeter reads when it 's what! With marketing refraction change suddenly then the change in direction of travel of is. An E-calculator ( ITA ) by setting the local altimeter true altitude formula is 29.52 and reading... Mean all sorts of different true altitude formula act in four movies in six?. ) = 82 62 true altitude formula 8 2 6 2 4 I quickly learned there.: 983 hPa altitude: FL 85 outside air temperature ( t ) - see )! Must consider when planning a flight to true airspeed while actually in flight a... = 40 + 200 = 240 shall show that total corrections are tabulated separately for stars,,! Finding the formula pressure at altitude gives us an ISA Deviation of -5C -35 =.! Attribution to the proper atmospheric conditions ( typically standard conditions ) ) as being correction window ways. Sonic Healthcare Workday, Gardner Denver Compressor Fault Codes, Desert Willow Fungus, Articles T