Learn something new every day if you stay awake huh. Defense Technical Information CenterFinally, the Calculate IAS subsystem uses the flap setting and calibrated airspeed to calculate indicated airspeed. At any other altitude, equivalent airspeed will be. 3905 33. 4. Look for the letters ‘CAS’ for calibrated airspeed and ‘TAS’ for true airspeed. 2. This speed is influenced by the head- and tailwind, the GS will be higher than the IAS/TAS if the aircraft experienced tailwind and vice versa. In this example, pressure altitude is 10,000 feet, temperature The airspeed indicator measures the difference between the static pressure from static ports and the ram pressure from the pitot tube. (Pilots usually talk about indicated (or calibrated) airspeed rather than true airspeed. You do this using an E6B. Calculate the Mach number at which the airplane is flying. ------#calibratedairspeed #e6b #ifrThe meaning of CALIBRATED AIRSPEED is the reading (of an airspeed indicator) corrected for instrumental and installation errors. Wind speed can be measured in knots, mph, or km/h. Hg. To calculate a pressure altitude's actual height, you have to calculate the difference between the regional QNH and the 29. Easily swap between true airspeed, calibrated airspeed, equivalent airspeed, and Mach number. The center of pressure moves forward as the angle of attack increases and rearward as the angle of attack. 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. Up until Mach-related effects come into play, CAS is what the airplane 'feels' as speed, and consequently, is all the pilot needs to know. You can see the true airspeed based on the example calibration tables modeled in the Calculate CAS block. Atmospheric Pressure or Pressure Altitude and see the remaining field be calculated. 1) the following: (a) pressure ratio (b) pressure altitude (c) temperature ratio (d) density. The reason is somewhat deeper than just the indication. I am using two pressure sensors to measure altitude & airspeed via static /pitot lines. CAS is IAS corrected for instrumentation and position errors. 7. 4. Because there are errors in the indicated airspeed, each manufacturer is required to measure airspeed and then provides data of indicated vs calibrated airspeed data. (FLASHING) T 232. 465 mps 4. 29 minutes. Collect flight data on 3 legs 90 degrees apart. 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). Calculate Calibrated Airspeed. It is important to TAS, then use the OAT and PAlt at the planned flight altitude . Obtaining CAS from IAS. $endgroup$ – Pondlife. . Previous Topic. $egingroup$ @Jimmy -- the whole point of the "polar curve" (airspeed versus L/D) well-beloved of glider pilots is that you are assuming 1-G steady-state flight. Interestingly, in most modern aircraft, what the pilots see in the cockpit is the CAS, but as the difference. Step 3: Fill in the wind speed. A free windows calculator which converts between various airspeeds (true / equivalent / calibrated) according to the appropriate atmospheric (standard and not standard!) conditions. 00347 1 T 0 = 1 288. Remembering the relationship between the various speeds and understanding the conversion from one to another can be facilitated. Calculate the true airspeed and the calibrated airspeed. Equivalent airspeed is calibrated airspeed corrected for the compressibility of air at a non-trivial Mach number. True airspeed is calibrated airspeed corrected for altitude and nonstandard temperature. This value is not corrected for installation error, instrument error, or the actual encountered air density, [2] being instead calibrated to always. 2Equivalent (or calibrated if you're slow enough) airspeed is also used in calculating lift. You need to specify the altitude at which you would like to perform the calculation as well as any one of the four airspeeds . [In straight flight]: Assume that wind speed is fixed, calculate airspeed from wind speed, ground vector and heading. Step 2: Enter the aircraft's true airspeed. What is the equivalent airspeed? 5. 5 ft. Published V-Speeds. If you shot a police radar gun at a plane flying by, you'd be measuring groundspeed of the airplane. To correct for these errors, manufacturers provide an airspeed calibration chart for each aircraft. At the model's position, the pressure coefficient is –0. Version 1. 8. Calibrated airspeed is indicated airspeed adjusted for a variety of errors. Groundspeed is the speed of the aircraft in relation to the ground. Any initial heading will do so long as the turns are 90 degrees and in the same direction. Alternatively, you can use the below equation to calculate calibrated airspeed: Image: Wikimedia. with θ being the angle between the horizon and the path of the aircraft in the vertical plane. 51 x 104 N/m2 . Indicated airspeed is based on. Calculate the Calibrated Airspeed. What Calibrated airspeed would you need to fly at in order to maintain a true airspeed of 150kts at 11,000’ MSL with a temp of 6°C How would you calculate necessary CAS in order to maintain a certain TAS, completely by hand? Not allowed to screenshot or use the exact question. To enable this port, set Airspeed input to TAS or EAS and. This is simple. 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). Among the common conventions for qualifying airspeed are: indicated airspeed ("IAS"), calibrated airspeed ("CAS"), true airspeed ("TAS"), equivalent airspeed ("EAS") and density airspeed. The pilot reads an Indicated Airspeed (IAS) of 280. Look up True Airspeed in your POH, and convert from MPH to KNOTS for your Nav Log. 3. For the purpose of lift and aircraft performance we calculate the kinetic energy by replacing the M (mass) in the formula by air density (mass of the air per square meter),. Indicated Airspeed from True Airspeed Calculation; On this page; Provide a True Airspeed; Calculate the Calibrated Airspeed; Adjust to Indicated Airspeed for Pitot-Static Airspeed Indicator; See Also; Related TopicsThe calibrated airspeed (CAS) indicator: This type shows the indicated airspeed that has been corrected for instrument and position errors. In practise the differences between calibrated airspeed (CAS) and indicated airspeed (IAS) on a light aircraft are usually small but calibrated airspeed should be used if trying to calculate a more. Your POH usually lists a bunch of power settings and the TAS and fuel burn for each one. In some very high speed aircraft equivalent airspeed is calculated instead of. That's because your airspeed indicator reports a slower speed than true airspeed as density decreases, based on altitude and air temperature changes. : All airspeeds shown are expressed in Knots Indicated Airspeed (KIAS) and are based on the aircraft . Indicated air speed (VIAS) is the speed indicated in the cockpit based upon the above calibration. Calculate the Dynamic Pressure ‘q’ [lb/ft2], based on the TAS above; make sure to use a formula consistent with a Lift-Off Speed in kts. Calculators. In this video, I go through a quick example of how to find true airspeed from indicated airspeed using the electronic E6B. If the ambient air temperature is 300 K, calculate the true airspeed and the calibrated airspeed. True Airspeed Calculator. 26. 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. Equivalent airspeed. For example, the knots multiplied by 1. How do you measure and calculate TAS manually? Measure indicated airspeed. However, temperature and altitude also affect the behavior of an aircraft in flight. Finally, the Calculate IAS subsystem uses the flap setting and calibrated airspeed to calculate indicated airspeed. . KNOTS vs. The airspeed and the setting of flaps should be adjusted before starting the turn. Calibrated Airspeed (CAS) can be converted to True Airspeed (TAS) using the formula TAS = CAS / √ρ/ρ₀, where ρ is the air density at altitude and ρ₀ is the. At standard sea level, EAS is the same as calibrated airspeed (CAS) and true airspeed (TAS). 16 4576. Opposite the "12" mark (which stands for 120 knots in this case) on the B scale, see your true airspeed-133 knots-on. P/Po) using Fig. Add the outcome to your indicated air speed (IAS)Calibrated Airspeed gradually deviates from True Airspeed as altitude increases. PITOT TUBE. CAS is calibrated airspeed. 54 5162. First connect the two tubes coming out the back to the airspeed sensor. TAS *can* be used but requires additional data. Using your flight computer, calculate the cruise density altitude. Released: Aug 31, 2022. This gives you density altitude. A pitot tube on the nose measures a pressure of 14. Knowing your True Airspeed has other advantages as well. In flight, it can be calculated either by using an E6B flight calculator or its equivalent. And indicated airspeed is equivalent airspeed plus measurement errors (calibrated airspeed is cleared of those errors, that can be effectively estimated). Although indicated airspeed (IAS) and true airspeed (TAS) are the speeds most commonly used in aviation, references to calibrated airspeed (CAS) and equivalent airspeed (EAS) are quite often encountered. 77 deg R,. V-Speed Symbol Speed Value What Is It? V SO 44 KIAS Stall speed or minimum steady flight speed in the landing configuration (flaps fully extended). 10) The correction form EAS to True Airspeed (TAS) is dependent upon: density ratio alone 11) An airplane operating an airfield which has a barometric pressure of 27. It is set to a default value of 1 . 9); make sure to use a formula consistent with a Lift-Off Speed in kts. Where IAT is the Indicated Air Temperature and ΔT is the Temperature Rise. Calculate the Calibrated Airspeed. The upper limit is 80 kilometers. and a runway temperature of 100 degrees F. Take your pick. A Pitot tube on the wing tip measures pressure of 4. Know the difference between indicated, equivalent, calibrated, and true airspeeds. 6 m/s (133 knots) despite the fact that you are moving with 75 m/s (146 knots) with respect to the air. After all the interesting discussions in the thread, I think these are the essentials of why calibrated airspeed (CAS) matters to the average pilot: You need to know CAS to calculate TAS for flight planning, and to calculate actual winds aloft when you're airborne (but it's usually a minimal difference from IAS at cruise speeds, so you can. KTAS (Knots True Airspeed) Airspeed corrected for changing atmospheric pressure at different altitudes. Calibrated airspeed is usually only a few knots different. In the airspeed window enter FL400 against the OAT. A properly configured airspeed sensor can greatly improve the ability of Plane to maintain altitude in auto-throttle modes (such as AUTO, CRUISE and FBWB), as well as greatly improve automatic landing. 20 1144. I just wanted to mention that the non-approximated version of the formula to compute the true altitude is: htrue = h + h T0 ⋅(TOAT −TISA) (1) (1) h t r u e = h + h T 0 ⋅ ( T O A T − T I S A) where the value usually represented by 4 1000 4 1000 is in fact 1 T0 = 1 288. indicated airspeed on a compressibly calibrated airspeed indicator d) equivalent airspeed @ 30,000 ft, P = 628. 3. Scroll to Top. And by subtracting one from another, you get your IAS. Any sustained climb will require full power, and most controlled descents start with a reduction of anywhere between 300 and 600 rpm. For the purpose of lift and aircraft performance we calculate the kinetic energy by replacing the M (mass) in the formula by air density (mass of the air per square meter),. 9. Above 35 knots, the deviation between the two systems varies between about –1 knots and +2 knots. You cannot copy the content of this page. The dependency is quadratic on airspeed (double airspeed, 4x the lift), and more or less linear on AoA (until you get closer to stall). Among the common conventions for qualifying airspeed are: indicated airspeed ("IAS"), calibrated airspeed ("CAS"), true airspeed ("TAS"), equivalent airspeed ("EAS") and density airspeed. Mar 4, 2016 at 3:35. 340. Airspeed Conversions (CAS/EAS/TAS/Mach) An airspeed calculator designed to convert between indicated/calibrated airspeed and true air speed. An ADC can determine the pressure altitude, vertical speed, calibrated airspeed, true airspeed (TAS), and density altitude (DA). just look in the POH and see if the prominent airspeed limitations such as Vne/Vmo are shown as IAS or CAS on the airspeed tape. Calibrated airspeed is more accurate than indicated airspeed because it includes additional variables that affect the true airspeed of the aircraft. The IAS is a good representation of the air’s. Problem 5: A high-speed subsonic aircraft is flying at a pressure altitude of 10 km where the ambient temperature. The indicated airspeed (IAS) from the flight and airspeed calibration table are used to determine the calibrated airspeed (CAS) for the flight. TAS is CAS corrected for altitude and non-standard. It’s the speed at which you move through the air, and it increases as altitude increases. These tables defined for different drag devices status (e. The model's Display block shows both indicated and calibrated airspeeds. The ground speed and track direction can be calculated by repeatedly measuring the location of the aircraft and dividing the distance by the time between measurements, or with modern aircraft it can be read directly from the GPS display. E6B. 765 in Hg. The tube coming straight out the back should go into the top port and the tube exiting at an angle should connect to the bottom port on the airspeed sensor. K and k = 1. have to be calibrated via flight tests. CAS has two primary applications in aviation: for navigation, CAS is traditionally calculated as one of the steps between indicated airspeed (IAS) and true airspeed (TAS); for aircraft control, CAS is one of the primary reference points, as it describes the dynamic pressure acting on aircraft surfaces regardless of the existing. Calibrated airspeed in knots is usually abbreviated as KCAS, while indicated airspeed is abbreviated as KIAS. K and k = 1. Airspeed. By flying three different headings and mathematically crunching the geometry, we can precisely determine both the speed and. PLANNED TRUE AIRSPEED (PLAN TAS) This function is used to calculate true airspeed for preflight planning. 149, Minimum Control Airspeed (Vmc) is the calibrated airspeed at which a multi-engine aircraft should fly when there is loss of a critical engine. If you were flying at sea level conditions, true airspeed would be equal to calibrated airspeed and there would be no need for a calculation. One of the difficulties in using GPS speeds to calculate airspeed is the effect of wind. The program at internet. True airspeed (TAS) - IAS cor rected for instrument installation error, compressibility error, and errors due to variations from standard air density. If the localizer is swinging one way or the other, then make a 1-2 degree correction to avoid chasing. Density altitude is a condition that affects aircraft performance. How to calculate calibrated Airspeed using E6B? To do this, you need to get Outside air temperature OAT from the metars, determine your True Airspeed from yo. Here the speed is displayed both in knots (kn) and miles per hour (mph). The formula for CAS is long and nested. This is the point of your cross-country p. CAS = interp1( flaps0IAS, flaps0CAS, fltdata(:,4) ); The atmospheric properties, temperature (T), speed of sound (a), pressure (P), and density (rho), are determined at altitude for standard day using. These calculations are based on the International Standard Atmosphere (ISA) & U. . Again, we are assuming that the pressure readings are perfect. 2 Answers. 4. For ease. So if an airplane has a groundspeed of 100kts it will fly 100nm per hour relative to the ground. Software Development ::. Modified 4 years, 11 months ago. The derivations of equations (1) and (2) are found in reference 1. IAS figures in aircraft manuals are actually converted from CAS. Is there such an equation that relates these principles together. 2GPH = 7. A pitot tube on the nose measures a pressure of 14 in Hg. Calculate (or find from Table 2. At the same time, an incorrectly configured airspeed sensor can cause. A high-speed subsonic McDonnell Douglas DC-10 airliner is flying at a pressure altitude of 10 km. Aircraft Performance Assignment 2 This assignment is applicable to a jet aircraft. But, back to the controller’s request to. Calibrated airspeed is defined as the indicated airspeed corrected for instrumentation errors in the pitot-static pressure measurement system. Add 2 minutes for climb-out. CAS is another type of airspeed used in aviation, and it is not corrected for wind effects like ground speed. None of the choices 1290. At the most basic level the Mach formula is: Mach = TAS/Speed of Sound The speed of sound is a slightly non-linear function of temperature: 38. 3) Groundspeed (GS) The movement of your airplane relative to the ground is called groundspeed. What you see on the dial, is the IAS. It is also the airspeed at sea level in the International Standard Atmosphere at which the dynamic pressure is the same as the dynamic pressure at the true airspeed and altitude at which the aircraft is flying. KIAS (Knots Indicated Airspeed) The speed of the airplane through the air. The calculation side. In the aeroblk_calibrated model, the aircraft is defined to be traveling at a constant speed of 70 knots (indicated airspeed) and altitude of 500 feet. (412TW-PA-12762). The lift force acts through the center of pressure, which frequently is slightly behind the airplane’s CG. MH (Compass deviation card) Cruise Performance 5-20. By vector subtraction you can also calculate the wind vector (speed and direction) if you get a velocity. True airspeed is calibrated airspeed corrected for non-standard atmospheric pressure and temperature. Then I would go into the FLT menu on the CX-3, and select Airspeed, and I would input all the values that you have, such as OAT, pressure altitude, and now CAS (calibrated airspeed) 0 Votes. View the true airspeed vs. With the current popularity of machine learning I think the calibration. What you see on the dial, is the IAS. Calibrated Airspeed (CAS) corrected for altitude and non-standard temperature - the speed of the aircraft relative to the airmass in which it is flying. CAS is calibrated airspeed. 0065 K/m (Kelvin per meter); h: Altitude above Mean Sea Level (MSL) (meters); Tc: OAT Estimation Correction (Kelvin); Impact on Society. To calculate the calibrated airspeed, you adjust the true airspeed for errors introduced through the pitot-static airspeed indicators used to determine airspeed. Can also convert to Mach number and Equivalent airspeed. When flying at high altitudes and higher airspeeds, calibrated airspeed is always higher than equivalent airspeed (EAS). The Navigation Computer: Airspeed Indicator Errors - Application of Corrections. It’s the aircraft speed relative to the airmass in which it’s flying. Equivalent airspeed (EAS) takes into account another correction. The calculation of true airspeed requires air density, which is determined from measurements of temperature and pressure. Indicated airspeed is measured using the pitot-static system. This is the complete guide to explaining V speeds in aviation. Calibrated airspeed (CAS) is calculated from IAS and correcting it for measurement errors. #1 Take half of your altitude and add it to your indicated air speed (IAS). 7. 15 K (Kelvin); L: Standard Lapse Rate, 0. 50 lbs/ft2, T = 411. If you shot a police radar gun at a plane flying by, you'd be measuring groundspeed of the airplane. 2 as a function of the boom system calibrated airspeed. Table Lookup (Default) Generate output airspeed by looking up or estimating table values based on block inputs. Working on programming my own E6B and am stuck trying to calculate the following problem from Sporty's E6B: Given wind info and desired speed/course, what. com or. If using the lower portion (2nd calculator), enter the Absolute. It’s the speed at which you move through the air, and it increases as altitude increases. At sea level in the International Standard Atmosphere (ISA) (ISA), and at slow speeds where air compressibility is negligible, IAS corresponds to TAS. True Airspeed. Jun 30, 2003 #1 How do you calculate Calibrated Airspeed? Thanks for your help. Description. How to use the true airspeed calculator? Below are tips for using the true airspeed calculator and understanding how it works. To calculate airspeed, we convert the pressure of air that is. Add 2% per thousand feet of climb. 0) at a calibrated airspeed of 290 kts. Type in 220. 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. Assume air is a perfect gas. as = airspeed ( [84. 0 . Calibrated airspeed is defined as the indicated airspeed corrected for instrumentation errors in the pitot-static pressure measurement system. spreadsheet program that will solve the problem. Back to Lesson. 66. indicated airspeed on a incompressibly calibrated airspeed indicator c) indicated. IAS is the airspeed read directly from the aircraft’s airspeed indicator. Calibrating an Airspeed Sensor¶. So we can calculate the new ratio as: Letʼs look at the airspeed indica-tor as an example. At sea level under ISA conditions, equivalent airspeed and calibrated airspeed are the same. In still air, the TAS is equal to the groundspeed. |. Calculate the Calibrated Airspeed. ρ = Local air density p = Local static pressure γ = Specific heat ratio = 1. There are speeds and then there are speeds. Assume R = 287. 4538. One of the difficulties in using GPS speeds to calculate airspeed is the effect of wind. Calibrated airspeed, VC. Beyond indicated airspeed and true airspeed, pilots can also calculate calibrated airspeed by utilizing standard position and instrumentation errors in order to correct the indicated airspeed value. AVERAGE_AIRSPEED = the average airspeed you got during the test ; AIRSPEED_INCREASE = the amount you want to increase the average airspeed by . Use equivalent airspeed to calculate true airspeed. Now determine gallons of fuel per 100NM based on your TAS, GS and fuel burn. It is the altitude where the air density under ICAO Standard Atmosphere conditions is equal to the actual density. 3 Wind Axis System. See moreIndicated Airspeed (IAS) The direct instrument reading obtained from the. In simple terms, it's the result of thrust impeded by drag. Calculators. For our purposes, equivalent airspeed is close to indicated airspeed in a well-calibrated system at sea level at standard pressure and temperature. Remembering the relationship between the various speeds and understanding the conversion from one to another can be facilitated. Wind Speed: The speed of the wind encountered by the aircraft. The IAS is a good representation of the air’s. Description. Answers: M1 = 0. Problem is, I don't have a Mach number to solve the equation. Calculate the Mach number, true airspeed and calibrated airspeed at which the aircraft is flying. Andrew Wood. Calculate the True Airspeed (TAS) in kts. True Airspeed (TAS) is the actual speed of the aircraft through the air corrected for altitude and temperature. At this airspeed, the IAS and CAS are the same due to the AOA and "design" of the pitot tube. This expression is based on the form of Bernoulli’s. "An extension of this idea is to fly three legs at the same altitude and airspeed. In some applications, notably British usage, the expression rectified airspeed is used instead of calibrated airspeed. This value is not corrected for installation error, instrument error, or the actual encountered air density, [2] being instead calibrated to always. Calibrated airspeed is IAS corrected for installation and instrument errors. KTAS is true airspeed given in knots. Airspeed is a powerful and easy-to-use templating engine for Python that aims for a high level of compatibility with the popular Velocity library for Java. Flight data was. 4. Airbus A350. It will compute the true airspeed in knots and Mach number and density altitude, given the pressure altitude, temperature, and calibrated airspeed in knots. Greg Bajor/Getty Images. The airfield elevation is 246 feet6. 27 minutes. Calculate the Mach number at which the airplane is flying. A high speed subsonic Airbus A320 airliner is flying at a pressure altitude of 8 km. I found a lot of rules of thumb. 校準空速 （ Calibrated Air Speed ）也稱為 校正空速 ，為一航空術語，是在修正儀表誤差及位置误差後，在 空速表 （英语：airspeed indicator） 上顯示的 空速 ，其缩写形式为 (CAS)，用符号Vc表示。. The formula for the ground speed of an airplane is, mathematically speaking, the square root of the square of the sum of the air speed and the wind speed in vector form. KCAS (Knots Calibrated Airspeed) Like KIAS, but corrected for instrumentational or positional errors. E6B, NavLog Calculator, Weather Reports, METAR, TAF, Wind Components, Instrument Simulator, Weight and Balance, Pressure Altitude, Density Altitude, True Air Speed. 7. This chart allows a pilot to correct for the discrepancies and calculate the calibrated airspeed (CAS). . Select the Airspeed The Airspeed function can compute the true airspeed submenu Press: (TAS) for a planned calibrated airspeed (CAS) with the 1 5 0 and tap enter to input 150 knots inputs Planned CAS, OAT, and PAlt . Calculate True Airspeed Given Indicated Altitude, Altimeter Setting, Temperature, and Indicated/Calibrated Airspeed. 225 from my research. load factor, N Z =1. In this example, pressure altitude is 10,000 feet, temperature is 2°C, and CAS is 200 knots. Up until Mach-related effects come into play, CAS is what the airplane 'feels' as speed, and consequently, is all the pilot needs to know. $egingroup$ My understanding is that you could calculate TAS from CAS derived from the IAS you observe, but the derivation for your particular aircraft may differ slightly from the factory plans, so using the HHT with GPS to calculate TAS would give an entirely independent measure of TAS that you could use to verify your calibration. Multiply the speed by the conversion ratio to convert a knot measurement to a mile per hour measurement. Opposite the calibrated airspeed (CAS) on the B scale note the true airspeed (TAS) on the A scale. Andrew Wood |. This chart allows a pilot to correct for the discrepancies and calculate the calibrated airspeed (CAS). Eastbound into 100 kt headwind with a true airspeed of 250 kts results in a GS of 150 kts. In the aeroblk_calibrated model, the aircraft is defined to be traveling at a constant speed of 70 knots (indicated airspeed) and altitude of 500 feet. 92 in the altmeter. PRESSURE ALTITUDE, CALIBRATED AIRSPEED, AND MACH NUMBER FRANK S. GS = TAS + W * cos θ. They are shown in IAS on. qc = Impact pressure; P0 = Standard pressure at sea level. eg 250KIAS @ FL240 ⇒ 240/2 = 120 ⇒ 250 + 120 = 370 kts (TAS) #2 Divide your altitude by 1,000 then multiply by 5. If the ambient air temperature is 300 K, calculate the true airspeed and the calibrated airspeed. 3. Calculate True Airspeed (TAS) from data using internet program. Airspeed is measured in knot or kilometres per hour. ground speed section above to learn more about the differences between the two. An airspeed calculator designed to convert between indicated/calibrated airspeed and true air speed. For example, the IAS can be referenced for altitudes below 10,000 ft (3,000 m) and 250 knots (460 kph). A high-speed subsonic aircraft is flying at an altitude where the pressure and temperature are 150 000 Pa and 250 K, respectively. I did 3 legs on my private XC navlog, but it’s really as many as necessary (it could be 1, 2, 3, whatever). I already take some factors to the 3. A high speed subsonic Airbus A320 airliner is flying at a pressure altitude of 8 km. You then use a flight computer (such as an E6B) to convert calibrated airspeed to true airspeed, based on the altitude and temperature at which you're flying. . site by Doug Gray was used because it matches the example table.