” We’re either going to have to calculate rho (air density) or calculate density altitude. We sit five exams, for example, not seven - meteorology, navigation and flight planning & performance are grouped together as one paper. 1) the following: (a) pressure ratio (b) pressure altitude (c) temperature ratio (d) density. 8. 6kft; then drops 1. The density altitude is the altitude relative to standard atmospheric conditions at which the air density would be equal to the indicated air density at the place of observation. This is useful for converting. e. 55 * CAS Use equivalent airspeed to calculate true airspeed. So far for central side. 8 * 1000) + 120 = 19000+120. Note you should generally expect TAS to be greater tha. For example, the indicated airspeed (IAS) of my Comanche at 8,500 ft. So if an airplane has a groundspeed of 100kts it will fly 100nm per hour relative to the ground. Ok thanks so much I was so freaking confused why 320 was overspeed if it goes so much. Hank S En-Route. 0kts. (Outside of the airspeed guage, which as a stand alone item is usually very accurate, errors can be caused by pitot tube and static port mounting locations and large changes in angle of attack. TAS=IAS/sqrt (delta) where Delta=ratio of air density to ISA SL density. Substitute the measured value as x into the equation and solve for y (the “true” value). Speed and rate of climb. When in flight you can calculate your true airspeed based on the indicated airspeed and density altitude. Groundspeed/TAS and IAS. True Hdg Mag Var. We don't have to know how to calculate TAS from IAS at PPL level and other navigation calculations are very simple ones, so no need for flight computers or electronic calculators. Suppose you are flying in a light aircraft at 80 knots. The last step is to convert TAS back to IAS because this is what you will be referring to on your airspeed indicator. For ease. For example, the indicated airspeed (IAS) of my Comanche at 8,500 ft. Generally, TAS = SQRT (air density sea level /air density at altitude) * CAS. As an example, at a given weight, an aircraft will rotate and climb, stall or fly an approach to a landing at approximately the same calibrated airspeeds, regardless of the elevation, even. :) $\endgroup$ – Calculate the True Air Speed. This is the point of your cross-country p. 2. True Airspeed Calculator. Suppose you are flying in a light aircraft at 80 knots. . 8. Basically IAS-->CAS, Find PA with altimeter setting and CA, and align on E6B. 2*(IAS/CS_0)^2)^3. Use the atmoscoesa function to first calculate the speed of sound (sos) and static air pressure (P0). The measurement of deferred tax is based on the carrying amount of the entity’s assets and liabilities (IAS 12. Here are a few examples of indicated airspeed (IAS) versus knots true airspeed (KTAS): 6,700 feet at 125 IAS = 142 KTAS; 9,000 feet at 125 IAS = 147 KTAS;. TAS = 280 + 165 = 445. So as a plane climbs at a constant IAS, the plane will be fast approaching its limiting Mach number (MMO). ago. Always check your actual TAS against the TAS you filed on your flight. The airspeed, however, doesn't factor in the wind. Learn something new every day if you stay awake. Calculate the True Airspeed (TAS) in kts. If you set IAS for you intended Mach at cruise that’s not what it will go to it will capture the Mach speed when passing FL280. It's worth more than 5 knots at 10,000 in a 172, and the difference in climb rates up there is huge. That means it takes a slower TAS to get to any given Mach number the higher the plane climbs. Calibrated Airspeed (CAS)Application of speed adjustments by an air traffic controller to Aircraft for the purpose of Aircraft separation. Mubashir December 14, 2016, 7:21pm 3. At sea level, with an atmospheric pressure of 1013. 10,000m - 306km/h - 0. 3) Groundspeed (GS) The movement of your airplane relative to the ground is called groundspeed. It does not account for altitude or temperature variations. The ASI measures the pressure differential between. The rate of turn is inversely proportional to the (True) airspeed. -2. = 300 Knots TAS. With the exception of goodwill and certain intangible assets for which an annual impairment test is required, entities. Note that at higher altitude the airplane will fly faster and proportionally sink faster, so the indicated sink speed in the second case. By the way, is it possible to calculate airspeed (IAS, not TAS) for planes? I suspect if wind exists in KSP but perhaps it is possible to make a model for airspeed on different altitude. If you ever plan to fly on a private charter, this will factor into calculating your flight price. You can measure it on board the plane using simple instruments called Pitot tubes: they are the tiny straws poking out of the aircraft's nose. Finally, now that you have gathered all of the variables necessary, use the following equation to determine the true airspeed by modifying the equivalent airspeed for temperature and pressure altitude variables: In the above equation, TAS is the true airspeed, EAS represents the equivalent. Many hours. AGL stands for above ground level, while MSL refers to mean sea level. Always check your actual TAS against the TAS you filed on your flight. If you could do that, it would become a killer feature of your mod. Groundspeed incorporates that and the wind direction and velocity at altitude. For those of us still flying Piper Cubs and such, a rule of thumb that works pretty well up to 10,000 feet is to add 2 knots for every 1,000 feet of altitude to IAS to get TAS. The true airspeed at altitude is then obtained from Eq. requirements of IAS 12. MSL is 170 knots. IAS/CAS correction is available from the POH. To prove how accurate it is, I've used the same example as Bio15 so you can compare the results: IAS = 280kts. The main issue here is how to account for the current and future consequences of. Here are the steps you should follow to calculate TAS: 1. Tour Start here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and policies of this siteAn aircraft’s indicated airspeed (IAS) refers to the airspeed measured directly from the aircraft’s airspeed indicator (ASI), which is powered by the pitot-static system. Alternate approach that deals with more friendly numbers is to deal with coefficients. Wikipedia defines Density Altitude as: The density altitude is the altitude relative to standard atmospheric conditions at which the air density would be equal to the indicated air density at the place of observation. The new-engine-option (neo) offers 15-20% better fuel efficiency. At levels below FL 250, speed adjustments should be expressed in multiples of 10 kt based on IAS. TAS is the airplane’s speed through the air, relative to the air. Your E6B can calculate TAS if you know your pressure altitude and temperature, but for most of us our handy dandy G1000 calculates it automagically and displays it with IAS. Flight level (FL) 80. That is a ballpark, and it, for example, will not work when you are flying a U-2 at 70,000 feet. The True Airspeed will be the corresponding number on the outer scale. You may speed up the video if you are already somewha. 2. IAS is based on the instrument (or air data computer) converting the ram air pressure received at the pitot tube into a reading on the instrument. EAS is CAS corrected for compressibility. In this video, I go over how to calculate your True Airspeed during the climb portion of your cross-country flight. This works ok, and I get the correct result. What is the formula for TAS and ground speed? Ground Speed (GS) is different from TAS and is calculated by considering the aircraft’s TAS and the effect of. TAS & IAS - True airspeed and indicated airspeed. 37. TAS = m/s (d) Calculate the true dynamic pressure q. This tab also has notes that explain the abbreviations used in all tabs. Use equivalent airspeed to calculate true airspeed. Each value has significance to pilots. IAS stands for indicated airspeed. The corrected airspeeds are indicated airspeed (IAS), calibrated airspeed (CAS), and equivalent airspeed (EAS). 4-metre-tall wingtip devices) result in up to 4% reduced fuel burn over longer sectors. Then you also add the wind into the equation. Power, pitch, trim. The mechanics of airspeed control require managing three dynamic elements: power, pitch, and trim inputs. at 500 MSL, but he or she must calculate performance as if the airport were located at 5,000 feet. Click on Calculate and the TAS (or KTAS) will be returned as whatever value you entered, either mph or knots. Do same thing without aligning temperature to get TAS. Obtain Indicated Airspeed: IAS can be found on the instrument panel’s airspeed. Using the CRP5 to calculate TAS with the known variables above. The elevator moves the nose of the airplane up or down to set the pitch. ”. Then crank the 3-leg GPS GS data into the REA Comp (or similar GS->TAS calculation system) to get "actual" TAS. Joined Nov 4, 2015 Messages 5,532 Display Name. TAS = True Airspeed. (I can calculate TAS on my E6B and my iPad just for the record. The second application, however, remains critical. Calibrated Airspeed (CAS) is the IAS corrected for errors in measurement and instrument errors, on modern aircraft this is the airspeed displayed on the speed tape. 13. IAS (or CAS or EAS), by nature of how it's measured, includes a correction factor for density. Often TAS and GS are assumed (confused) to be the same, they are not. E6B, NavLog Calculator, Weather Reports, METAR, TAF, Wind Components, Instrument Simulator, Weight and Balance, Pressure Altitude, Density Altitude, True Air Speed. (460 kph). I'm looking for a formula to calculate the horizontal distance (guess it is the Ground Distance) passed during the phase of ascent (or descent), having the rate of climb in ft/min and the TAS in knots. The correct thrust for any desired altitude must be entered to get the equivalent airspeed at that altitude. How you would tap into the raw signal, dunno. Calibrated airspeed is IAS corrected for installation and instrument errors. qc = Impact pressure; P0 = Standard pressure at sea level. TAS is expressed in knots and is abbreviated KTAS. The difference between TAS and IAS is caused by changes in air density. Unless we must clear obstacles quickly after takeoff, our best climb-out airspeed is VY, the best rate of climb speed. Ailerons bank the wings to determine the rate of turn. At 35,000 ft, 250 KIAS (or KCAS) is. Airspeed Indicator. E6B, NavLog Calculator, Weather Reports, METAR, TAF, Wind Components, Instrument Simulator, Weight and Balance, Pressure Altitude, Density Altitude, True Air Speed, and a lot more. FL330. In simple terms, it's the result of thrust impeded by drag. Remember, the Airspeed Indicator displays the Indicated Air Speed (IAS), and adjustments are needed to calculate the Calibrated Airspeed (CAS) and True Airspeed (TAS). The true airspeed and heading of an aircraft constitute its velocity relative to the atmosphere. Follow. In service since January 2016. - the real force acting on the wall - or an other obstruction in the wind - is in general more complicated to calculate due to drag , turbulence and other effects. in IAS. 0 kts. The corrected airspeeds are indicated airspeed (IAS), calibrated airspeed (CAS), and equivalent airspeed (EAS). At cruise in a Cessna 172N at 10,000 feet at standard temperature, your TAS is predicted to be 114 KIAS at 2500 RPM. So, use the equation: TAS = IAS + (2% per 1,000 feet) (IAS)Doing 160 KCAS at 19000' you cover *roughly* 220 nautical miles in 1 hour of your flight. Let’s go through how to perform the calculation. Because of that, you can't directly measure true airspeed, but you can calculate it with an E6B (some analog airspeed indicators have a window to compute true airspeed as well). All values in the array must have the same airspeed conversion factor. 0 Pa, but due to an exceptionally hot summer, the air temperature has risen to 40°C. -----#calibratedairspeed #e6b #ifrA very simple rule of thumb is to add 2% to the calibrated airspeed for every 1000 ft of altitude. e. P 0 = Sea level pressure by reducing station atmospheric pressure to equivalent at mean sea level = QNH. $endgroup$ – John K(TAS). S. 8 prescribes that borrowing costs directly attributable to the acquisition, construction, or production of a qualifying asset must be capitalised as part of the cost of that asset, with a few exceptions. Any initial heading will do so long as the turns are 90 degrees and in the same direction. When the. TAS is approximately equal to CAS at sea level but increases relative to CAS as altitude increases. Using the CRP-5 to determine the TAS when given altitude, corrected outside air temperature and RAS/CAS. airspeed for best rate of climb tells us how airspeed changes with altitude for best rate or V(h)best R/C. This is a true airspeed to ground speed calculator thanks to the second true airspeed formula: In this video you will know how to calculate True Airspeed with E6B flight computer. FL330. If you call "K" a correction to a value,you have the following diagram : IAS (*K probe)--> CAS (*compressibility)--> EAS (*density)--> TAS Kprobe allows for the pitot system errors CAS = corrected a/s EAS = equivalent a/s Kcompressibility varies with altitude and IAS, between 1 and . This higher speed is the TAS. Also. CAS is IAS corrected for installation errors. If an aircraft maintains IAS, TAS (and therefore groundspeed) increases when an aircraft climbs. Set the rate arrow to 150. It is the controller's task to calculate the necessary IAS or Mach number that would result in the appropriate ground speed. IAS is depending on atmospheric conditions. This story is only one of many examples of how TAS helps resolve. Converting CAS <-> TAS requires us to look at air density, which is a function of both the pressure and temperature of the air. Question 2: An Airplane travels in air at 20°C at a speed of 2400 km/hr. Indicated airspeed (IAS) The indicated airspeed is measured through the airspeed indicator in the cockpit. I plotted this with the data in the first plat, and it's a pretty bad description. However, you can do division to work it backwards: 150/1. This value is dependent on the aircraft . A - Altitude of the airplane. temperature, together, directly affect the conversion of indicated airspeed (IAS) or calibrated airspeed (CAS) to true airspeed (TAS), whereas the conversion of indicated Mach number to TAS is only affected by air temperature. Pilots use these measurements at different times during the course of a flight. If you were looking for a "one liner" to use in a BASIC computer programme or such-like, the following should suit your purposes-. This is assuming IAS = CAS = EAS (i. The pilot reads an indicated airspeed (ias) of 290. Tap PLAN TAS from the. If an aircraft maintains IAS, TAS (and therefore groundspeed) increases when an aircraft climbs. This number will decrease as you gain altitude and increase as you lose altitude, even if your ground speed (speed relative to the ground) remains constant. [2] This is the pilots' primary airspeed reference. To find true airspeed, you’ll need an E6B flight computer. — Profile Valid: This allows you to set your profile On or Off once all data is entered . Kinetic Energy = Dynamic Pressure = IAS = ½ ∂ V2 where V is TAS -2-IAS is not really a speed. You can use the Aerospace Toolbox correctairspeed function to calculate TAS, CAS, and EAS from one of the other two. . The difference between IAS and CAS may be slight, but your Aircraft Information Manual will outline the adjustments and assist you in determining your Calibrated Airspeed or CAS. Calculators. Equivalent airspeed. It is then displayed on the screens, normally on the navigation display. This is because air density decreases. Description. However, as it does measure the IAS and altitude directly, the system is able to calculate the TAS for us. Your IAS will stay the same because if you recall the working principle of an. Add the outcome to your indicated air speed (IAS) If anyone can illuminate me with explaining every step to achieve TAS with given parameters, it would be great. Fundamentals Of Aircraft Design. Employee benefits are all forms of consideration given by an entity in exchange for service rendered by employees or for the termination of employment. 10% of IAS +7. The pitot tube points forward and measures the pressure of air ramming into the tube. TAS = the speed of an aircraft at any given altitude, given its true airspeed, outside temperature, and air density. It is actually only pressure calibrated as Indicated Speed (IAS). 3. You can then compare this to your planned figures from the performance charts to determine if adjustments are necessary to your flight plan (ETA, Fuel use, etc. Indicated airspeed (IAS) is the speed shown on the aircraft’s airspeed indicator. Remembering the relationship between the various speeds and understanding the conversion from one to another can be facilitated. 200 X 2% = 4 X 10 = 40 + 200 = 240. TOD = 21 nautical miles from arrival point. Use your flight calculator to perform the calculations to determine the. 6 KB. The calculation of the climb TAS is performed by: 1. (Depending on where you are, the temperature estimation can vary from about 1. The late model ones will absolutely do book performance when they are actually flown by the book. 1 Answers. 7. For example, at standard air density, a dynamic pressure of 1816. KIAS means “knots of indicated airspeed. . First calculate horizontal component of airspeed, then add the wind: v G S = c o s ( θ) ∗ v T A S + v w i n d. Study BASIC ATC ACFT flashcards. As you increase altitude, the air becomes less. 2. Or, if you are unfamiliar with trigonometry (using Pythagora's theorem): v G S = v T A S 2 − v v e r t i c a l S p e e d. Calculating the mean climb height and temperature 3. Second formula. ) they're not going to take all that info and calculate the resulting wind I have no idea, but if they want to it's easy, using an app or even a wind calculator on a. Involving velocity, pressure, density and temperature as functions of. The ASI will indicate less than TAS when the air density decreases due to increase in altitude or temperature. 4 kt. For these purposes, the indicated airspeed – IAS or KIAS (knots indicated airspeed) – is used. 55 CAS. The airspeed indicator measures the dynamic pressure of the outside air entering a pitot tube. An air data computer (ADC) is an essential avionics component found in aircraft. These systems take into account various factors, including altitude, temperature, and wind, to calculate TAS accurately. 3. How do you calculate TAS in aviation? TAS in aviation is often calculated using various methods, including the. In flight, it can be calculated either by using a flight calculator (E6B also known as a Dalton Computer, or its equivalent). tabhide===undefined ? . The corrected airspeeds are indicated airspeed (IAS), calibrated airspeed (CAS), and equivalent airspeed (EAS). GS =Groundspeed = speed that you get on radar gun as airplane flies by, when radar gun is held by someone on ground. TAS is approximately equal to CAS at sea level but increases relative to CAS as altitude increases. Wind does NOT affect True Air Speed (TAS). 5 (which is not the correct answer to the previous question). There are some formulas that can. Our calculator rounds at 3 decimal places, in this case. Calculate TAS using IAS Save Load Reset. Rate of turn is in degrees per second, θ θ is the bank angle in degrees, and. Formula of mach number is: M = v/c. a0 = Standard speed of sound at 15 degrees Celsius. If you know the air density, you can calculate the air speed. Remembering the relationship between the various speeds and understanding the conversion from one to another can be facilitated. Simulate Model to Display Airspeeds. Step 2 : Using the environment model, compute the temperat ure deviation ( ) and the windThis means at a given time, fewer molecules of air will make contact with the Pitot tube. Joined Nov 4, 2015 Messages 5,532 Display Name. Your tip speed (the vertical axis) is (presumably) the simple geometric speed, which depends only on RPM. q= kPa CheckIAS 41 sets out the accounting for agricultural activity – the transformation of biological assets (living plants and animals) into agricultural produce (harvested product of the entity's biological assets). Calculate the required thrust per engine in kN. 05x + 0. Tech Log - TAS from IAS, PA and OAT - I used formula TAS = IAS + (2/100) X IAS X (PA/1000) to manually calculate value. 0 . Joined Jul 3, 2013 Messages. It provides guidance for determining the cost of inventories and for subsequently recognising an expense, including any write-down to net realisable value. EAS = TAS only at ISA mean sea level density. The standard establishes the principle that the cost of providing employee. To calculate true airspeed, the indicated airspeed is adjusted based on the outside air pressure and temperature. 1. so your airplane is flying with a 3* angle to the horizon, if you draw a triangle lika that one below you have your airspeed as hypotenuse so your ground speed will be the horizon line. Instruments that record the TAS are also available, though uncommon in commercial aircraft. As you gain more experience you will start to learn what kind of true airspeed your aircraft gets at certain power settings. The rule of thumb I use is to add 2% to your airspeed per 1000' altitude. Property, plant and equipment is initially measured at its cost, subsequently measured either using a cost or revaluation model, and depreciated so that its depreciable amount is allocated on a systematic basis over its. H P = Station elevation relative to mean sea level. OR: Take 1/2 your altitude and add to your IAS; Divide by 1000; Multiply by 5; Add the outcome to your. How to estimate your TAS. 76, at which you will follow the Mach Number. First, true airspeed (TAS) is a complicated calculation involving indicated airspeed (IAS) and density altitude. Airspeed Conversions (CAS/EAS/TAS/Mach) Calculators. How do you calculate max crosswind ? 20% of VSO. This value is dependent on the aircraft . Indicated airspeed (IAS) is displayed in the cockpit instrumentation. For an aircraft in a level, coordinated turn, the rate of turn is given by. Calculate true airspeed using the E6B air navigation computer given indicated airspeed, calibration data, altimeter setting, indicated altitude, and outside air temperature to within +/- 2 KTS. KTAS is a correction to give you your true airspeed through the air mass given the current state of the air that you're flying through. TAS = True Airspeed = speed that you get on radar gun as airplane flies by, when radar gun is held by someone in gondola of balloon in same airmass (wind motion) as airplane. The E6-B is a circular slide rule on the front side, or ‘computer’ side, and a wind triangle calculator on the ‘wind’ side. How fast an airplane can go in level flight depends on the amount of drag and the amount of horsepower. Groundspeed incorporates that and the wind direction and velocity at altitude. In simple terms, it's the result of thrust impeded by drag. True Airspeed (TAS) : Density Altitude (DA) : Pressure Altitude (PA) : Note: Standard pressure is 29. g. TAS is expressed in knots and is abbreviated KTAS. φ. Search titles only; Posted by Member: Separate names with a comma. Mach Number - This is the ratio of the aircraft's true airspeed to the speed of sound, i. Is there a method that can be used to calculate TAS from an IAS with fluctuating temperature or press? Alternatively, TAS = IAS + 2 percent every 1000 feet of height. P-51D has 178km/h IAS stall speed but it needs to at least travel at 306km/h at 10,000m to maintain 178km/h IAS and avoid stalling. The facts are 160 mph IAS which is approximately 140 kias. True Airspeed (TAS): True Airspeed refers to the plane’s speed in relation to the air around it. Permalink. TAS, unlike Indicated Airspeed (IAS), accounts for changes in atmospheric density and temperature, giving pilots a more accurate measure of their speed relative to the air around them. The standard establishes the principle that the cost of providing employee. An ADC will normally calculate TAS as well (see the list of outputs above). From your GPS unit, determine the ground speed on each leg. with θ being the angle between the horizon and the path of the aircraft in the vertical plane. The corrected airspeeds are indicated airspeed (IAS), calibrated airspeed (CAS), and equivalent airspeed (EAS). Overview. 9812)x (PH<36089. True airspeed (TAS)I was hoping to find an accurate IAS equation that is only dependent upon TAS, static pressure and static temperature. 5 to 12 mins. True airspeed (TAS) is the speed at which an airplane is moving relative to the air that surrounds it. Mathematically increase your indicated airspeed (IAS) by 2% per thousand feet of altitude to obtain the true airspeed (TAS). True airspeed is equivalent airspeed with the changes in atmospheric density which affect the airspeed indicator removed. Note that to fly a particular course, you not only have to account for headwind, but to adjust the airplane heading, ‘crabbing’ into the crosswind. Rate of turn = 1091 tan θ V R a t e o f t u r n = 1091 tan θ V. 25 to about 800 hectopascals. e. 1. Alternatively, you can use the below equation to calculate calibrated airspeed: Image: Wikimedia. They are also resticted to only subsonic speeds. Note that climb and descent speeds are in knots in Indicated Airspeed (IAS) while cruise speeds are in true airspeed (TAS) (or Mach for Jets). If anyone has a Sporty's E6B, it is listed as Planned Mach # and Actual Mach # as well as Planned TAS and Actual TAS. 01 Mach. Overview. Any initial heading will do so long as the turns are 90 degrees and in the same direction. I’d first get from IAS to CAS with the correction chart. If we evaluate the above equation at we will get the equivalent airspeed. I used quick mission,. Because of the importance of this speed ratio, aerodynamicists have designated it with a special parameter called the Mach number in honor of Ernst Mach, a late 19th century physicist who studied gas. TAS = EAS/√ RD. Thats the quick formula for true airspeed. I have also given a f. Mathematically increase your indicated airspeed (IAS) by 2% per thousand feet of altitude to obtain the true airspeed (TAS). Don't forget that for larger climbs, your true airspeed will increase even though your calibrated/indicated speed remains constant. Use the equation of the calibration curve to adjust measurements taken on samples with unknown values. As an example, at a given weight, an aircraft will rotate and climb, stall or fly an approach to a landing at approximately the same calibrated airspeeds, regardless of the elevation, even. Below is a table of ISA values. ". IAS and TAS are identical at sea level and as you get higher due to the thinner air the IAS reading gets lower compared to TAS with altitude. This chart allows a pilot to correct for the discrepancies and calculate the calibrated airspeed (CAS). The IAS is a good representation of the air’s dynamic pressure, which is used to calculate the lift force the wing must generate at a given speed. 2 Answers. 24)-56. Calculate the True Air Speed. The objective of IAS 2 is to prescribe the accounting treatment for inventories. The air density decreases. For example, fly north, then east, and then finally south. Then the TAS can be read over the CAS which for GA aircraft can be IAS since it is relatively close to CAS. Or set the IAS wheel on your Airspeed indicator. The Board revised IAS 36 in March 2004 as part of the first phase of its business combinations project. In this short tutorial I will show you how to calculate the true airspeed from the equivalent airspeed. Thus, as a practical matter, you may usually use IAS rather than CAS to determine. This describes the aircrafts speed relative to the ground. wages and salaries, annual leave), post-employment benefits such as retirement benefits, other long-term benefits (e. The real measure of ground speed can be calculated by taking the horizontal speed of the aircraft relative to a fixed object at that altitude, and translating it ground level. TAS = 280 + 165 = 445. The transition happens around FL260 at which the Mach Maximum speed of the plane, intersects with the Maximum speed IAS of the plane. Divide that by 10, and you get 8. org. IAS = 70 knots. At this airspeed, the IAS and CAS are the same due to the AOA and "design" of the pitot tube. I'm using the HUD speed and averaging it at various points to get the speed.