Let's say your CAS is 120 knots. The model's Display block shows both indicated and calibrated airspeeds. In this example, pressure altitude is 10,000 feet, temperature is 3°C, and airspeed is 200. 82 in. "An extension of this idea is to fly three legs at the same altitude and airspeed. Problem is, I don't have a Mach number to solve the equation. If the ambient air temperature is 230 K, calculate the true airspeed and the calibrated airspeed. 4 and R = 287 J/(kg K)] Solution From the standard atmosphere table, p = 2. A pitot tube on the nose measures a pressure of 14. Thats the quick formula for true airspeed. 8. If the Subsonic airspeeds only check box is selected, the Ideal Airspeed Correction block generates code that includes subsonic (Mach < 1) lookup table data. ------#calibratedairspeed #e6b #ifrThe meaning of CALIBRATED AIRSPEED is the reading (of an airspeed indicator) corrected for instrumental and installation errors. How do you measure and calculate TAS manually? Measure indicated airspeed. Calibrated airspeed in knots is usually abbreviated as KCAS, while indicated airspeed is abbreviated as KIAS. Planned TAS Solution: Press the FLT key . 2 Answers. It is dynamic pressure, indicated as speed at which that dynamic pressure would occur at sea-level standard conditions. Because of the lower air density at high altitudes, the airspeed indicator reads lower than it would at the same speed down at a lower altitude. 2 as a function of the boom system calibrated airspeed. . However, I probably already calculate some of the factors for it in my Test Calculations. 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. In some applications, notably British usage, the expression rectified airspeed is used instead of calibrated airspeed. In this exa ple, press ure al ti de is 10,000 feet, tempera ure is 2°C, and CAS is 200 knots. If you shot a police radar gun at a plane flying by, you'd be measuring groundspeed of the airplane. Jun 30, 2003 #1 How do you calculate Calibrated Airspeed? Thanks for your help. 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. com or. 5. Equivalent airspeed can be defined in terms of true airspeed, as above, but it is also defined in terms of calibrated airspeed (CAS) corrected for adiabatic compressible flow at the altitude of flight. True airspeed is calibrated airspeed corrected for non-standard atmospheric pressure and temperature. You can see the true airspeed based on the example calibration tables modeled in the Calculate CAS block. If the ambient air temperature is 230 K, calculate the true airspeed and the calibrated airspeedCalculate the Mach number at which the airplane is flying. Navigation Log. Type in 220. 1. Speeds must be calculated in knots and pressures must be calculated in lb/ ft 2 . We're looking at how to find our true airspeed while in flight, and a bit about why true and indicated airspeed are different, and why it matters for things. Hg. Airspeed is typically measured using a pressure differential device called a pitot tube, and therefore is susceptible to variation at different altitudes. indicated airspeed on a incompressibly calibrated airspeed indicator c) indicated. 4538. 6). The calculation of true airspeed requires air density, which is determined from measurements of temperature and pressure. All cross country aviation calculations are based on flying at the planned true airspeed, generally defines as the speed of the airplane through the relatively undisturbed airmass. S. Convert between Calibrated Airspeed (CAS), Equivalent Airspeed (EAS), True Airspeed (TAS) and Mach number (M) using the tool below. θ - Angle between wind direction and aircraft motion. $\begingroup$ I think this answer to the other question you asked covers this. 7. Airspeed is measured in knots (nautical miles per hour) or in some cases, miles per hour (mph) or kilometers per hour (km/h). On older aircraft, airspeed is usually indicated to the pilot on a graduated scale over which a pointer moves ( the first diagram). Density altitude is a condition that affects aircraft performance. Now look on the B scale to find your calibrated airspeed (CAS), which can be found in the limitations section of your pilot's operating handbook (POH). The calibrated airspeed offset is defined by the manufacturer and posted in the pilot operating handbook (POH). It is the true figure for how fast you are moving through the air. 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. 𝑃2 𝑘−1 2 𝑘−1. In flight, it can be calculated either by using an E6B flight calculator or its equivalent. E6B, NavLog Calculator, Weather Reports, METAR, TAF, Wind Components, Instrument Simulator, Weight and Balance, Pressure Altitude, Density Altitude, True Air Speed. Simply enter the figure into the calculator, and you'll have the response in mph, ft/s, m/s, and km/h in the blink of an. After simulating the. Know the difference between indicated, equivalent, calibrated, and true airspeeds. After simulating the. At this altitude, the air pressure drops from 1013. Density Error Opposite the calibrated airspeed (CAS) on the B scale note the true airspeed (TAS) on the A scale. The CAS is used for aircraft certification and. Note you should generally expect TAS to be greater tha. To calculate the calibrated airspeed, you adjust the true airspeed for errors introduced through the pitot-static airspeed indicators used to determine airspeed. •. The mechanics of airspeed control require managing three dynamic elements: power, pitch, and trim inputs. It can also reduce the chance of a stall. If the ambient air temperature is 300 K, calculate the true airspeed and the calibrated airspeed. The errors are most pronounced in slow and high angle-of-attack flight. Calculate the Mach number at which the airplane is flying. 2. eg 250KIAS @ FL240 ⇒ 240/2 = 120 ⇒ 250 + 120 = 370 kts (TAS) #2 Divide your altitude by 1,000 then multiply by 5. For low speeds, the data required are static air temperature, pressure altitude and IAS; Above approximately 100 knots, the. If I want to calculate static air temperature (OAT), but I'm only given an altitude and a true airspeed. Note that calibrated altitude values reflect the altitude above Mean Sea Level, a constant value used in aviation and other. 853, V1/Vtrue = 259. The airspeed and the setting of flaps should be adjusted before starting the turn. Density altitude is an important factor for aircraft performance modelling. Airspeed is typically measured using a pressure differential device called a pitot tube, and therefore is susceptible to variation at different altitudes. In accordance to FAR 23. ) Determine the estimated time en route for a flight from Priest River Airport (area 1) to Shoshone County Airport (area 3). Wind Speed: The speed of the wind encountered by the aircraft. 20% faster than what you read off your airspeed indicator. Procedure: 1. 2. This calculator is designed to give a corrected value known as TAS, or true airspeed. Calculate the Mach number at which the airplane is flying. 1. To calculate True Air Temperature (T) use T= IAT-ΔT. Calculate the necessary values of the airstream velocity, temperature,. The wind is from 030 at 12 knots and the true airspeed is 95 knots. 7 p M 2. . Again, we are assuming that the pressure readings are perfect. Description An air data computer (ADC) is an essential avionics component found in aircraft. 若是在高速、高海拔的條件下，校準空速還需要修正由於空氣可壓. And by subtracting one from another, you get your IAS. Lift is a function of dynamic pressure, as are equivalent airspeed and true airspeed, but to calculate dynamic pressure from true airspeed requires knowing (or calculating) the local density. The following terms have been auto-detected the question above and any answers or discussion. 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 . Assume R = 287. This function is used to calculate true airspeed for preflight planning. 15)In this video, I go over how to calculate your True Airspeed during the climb portion of your cross-country flight. Collect flight data on 3 legs 90 degrees apart. A high-speed subsonic McDonnell Douglas DC-10 airliner is flying at a pressure altitude of 10 km. In some applications, notably British usage, the expression rectified airspeed is used instead of calibrated airspeed. A simple computational procedure (see, for example Advisory Circular 23-8B, FAA, 2003) allows one to compute true airspeed, wind speed, and wind direction. 2. 4. So if an airplane has a groundspeed of 100kts it will fly 100nm per hour relative to the ground. Within the realm of Aeronautical Engineering and Aviation, True Airspeed (TAS) plays a pivotal role. Collect flight data on 3 legs 90 degrees apart. Finally, the Calculate IAS subsystem uses the flap setting and calibrated airspeed to calculate indicated airspeed. The model's Display block shows both indicated and calibrated airspeeds. For example, several type air-6. $\begingroup$ 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 equation. This used to be a much bigger deal when flights were conducted by dead reckoning, and reliable airspeeds were more directly beneficial to the flight planning and enroute process. CAS/Mach/EAS based on Altitude and TAS. 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. Now, imagine flow is started and some amount of gas is pile up inside the tube as the tube is closed from pressure gauge at point (B). 7. Airbus A330. Wind speed and direction can be calculated by subtracting the true air speed vector from the. One speed is the one you see in your Airspeed Indicator, and that is Indicated Airspeed (in knots generally), or KIAS (Knots Indicated Airspeed). A pitot tube on the wing tip measures a pressure of 200 000 Pa. Find out what your turn radius is at cruise airspeed up high and at approach airspeed down lower; find out what a 1° pitch change will do to your VVI and remember those numbers; The 60-to-1 Rule:In this short tutorial I will show you how to calculate the true airspeed from the equivalent airspeed. 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 (TAS) and altitude. Be able to calculate the true airspeed of. Find the Wind Wind is a problem during airspeed calibrations. Calculating Density Altitude. A free windows calculator which converts between various airspeeds (true / equivalent / calibrated) according to the appropriate atmospheric (standard and not standard!) conditions. This handbook, AFFTC-TIH-81-5, AFM Standard Airspeed Calibration Procedures, was submitted under Job order Number SC6601 by the Comander, 6520 Test Group, Edwards APB, California 93523. E6B. Once the test data is collected, the ADCs are calibrated so that the indications seen by the pilot in the cockpit are free of these errors. Calibrated airspeed is IAS corrected for installation and instrument errors. The equations for equivalent airspeed and for calibrated airspeed were developed from the true airspeed equation by setting selected local parameter values to their sea level, standard day equivalents. To learn more about how it works, read on. Modified 4 years, 11 months ago. 967854*SQRT(OAT+273. Description. In some very high speed aircraft equivalent airspeed is calculated instead of. As you roll in, increase power and angle of attack (pull the elevator) to maintain the airspeed and level flight. To calculate the calibrated airspeed, you adjust the true airspeed for errors introduced through the pitot-static airspeed indicators used to determine airspeed. 6 m/s (133 knots) despite the fact that you are moving with 75 m/s (146 knots) with respect to the air. 5. #1) Airspeed Indicator The Airspeed Indicator measures the speed of the aircraft through the air, but really this is the speed at which the air is flowing over the airplane. This is simple. Remembering the relationship between the various speeds and understanding the conversion from one to another can be facilitated. . The window that is between “1:30” and “1:50” on the hour scale is labeled “DENSITY ALTITUDE” and the arrow points to the density altitude. 31 minutes. You can calculate true airspeed by entering calibrated airspeed, pressure altitude, and temperature into a flight computer. The ASI measures the pressure differential between. 3Vs to Vne. Calculate the maximum rate of climb at each density altitude: ?ℎ?? = (?????) ?? (550)(60)? ? (feet/minute) 10. 1323(b) includes the following requirement for the airspeed indicating system: The system error, including position error,. . By vector subtraction you can also calculate the wind vector (speed and direction) if you get a velocity. In an emergency scenario with an inoperative engine, VMC allows for: • Maintained control • Maintained leveled flight (with an angle of no more than 5º)True Air Speed (TAS) is: CALIBRATED AIRSPEED(CAS) CORRECTED FOR COMPRESSIBILITY AND DENSITY ERRORS True Air Speed (TAS) is: EQUIVALENT AIRSPEED (EAS) CORRECTED FOR DENSITY ERROR. Calculate the recovery, purity, and efficiency. I already take some factors to the 3. Since the majority of the time, planes fly at high altitudes, an equation is needed to calculate true airspeed, and this is best done using your mach number (M) with the equation:$egingroup$ @shortstheory Ahhh, it's only a slight difference in terminology, but Mach 0. Step 4: Make a course selection. 54 5162. ) Share. 42 in. Jun 13, 2016. Can read ground speed (and often actual air speed) Calculate directly without calculating the calibrated airspeed as an intermediate step. Flight level (FL) 80. And remember, this is not a measurement of ground speed. This dictates that the true airspeed also lies along the same axis. Given: Calibrated airspeed (CAS): 155 kt. 16 4576. 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. 8. V speeds refer to just about any airspeed that’s used by pilots and all types of aircraft. For example, interference velocities generated by the presence of the fuselage or rotors may bias indicated airspeed, but are removed from calibrated. What you see on the instrument is called Indicated Airspeed (IAS). Released: Aug 31, 2022. Indicated airspeed is the starting point for all other calculations. . Airspeed is the velocity of an airplane relative to the air mass through which it is flying. Values of impact pressure qc calculated from equations (1) and (2), in. 2 Air Data Information and Its Use 379 3. Ground Speed (GS) The final type of speed that pilots use is ground speed (GS). How to use the true airspeed calculator? Below are tips for using the true airspeed calculator and understanding how it works. For our purposes, equivalent airspeed is close to indicated airspeed in a well-calibrated system at sea level at standard pressure and temperature. When in flight you can calculate your true airspeed based on the indicated airspeed and density altitude. Convert airspeed from true airspeed ( 'TAS') to equivalent airspeed ( 'EAS') at 15,000 meters. The Electronic E6B, once understoo. Determine the true and equivalent airspeed for a flight at 20,000 ft altitude. J. Don't get too dependent on those GPS's. 27 minutes. True Airspeed (TAS) is the actual speed of the aircraft through the air corrected for altitude and temperature. Login Accessing this course requires a login. Description. 3) Groundspeed (GS) The movement of your airplane relative to the ground is called groundspeed. You can set the true airspeed in the True Airspeed block in the model. 4. An ADC can determine the pressure altitude, vertical speed, calibrated airspeed, true airspeed (TAS), and density altitude (DA). 200 X 2% = 4 X 10 = 40 + 200 = 240. Multiply the speed by the conversion ratio to convert a knot measurement to a mile per hour measurement. 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). Find the Pressure ratio in a constant temperature atmosphere:. However, the second application remains important. Equation (1) may be developed from the isentropic flow equations, and allows us to determine true airspeed as a function of density and pressure: (1) V = 7 ⋅ p ρ ⋅ { ( Δ p p + 1) γ − 1 γ − 1 } where. Your POH usually lists a bunch of power settings and the TAS and fuel burn for each one. Related Content: The Ultimate Crosswind Calculator Cheat Sheet. The aircraft's Mach number, pressure. CAS does not account for pressure and density change with altitude when inferring your airspeed from dynamic pressure readings (ie the Pitot tubes). Viewed 784 times. PLANNED TRUE AIRSPEED. Any sustained climb will require full power, and most controlled descents start with a reduction of anywhere between 300 and 600 rpm. When you read the Airspeed on the Airspeed Indicator Flight Instrument, you are reading the Indicated Air Speed (IAS). You drop the flaps to 30 degrees and slow down to 50 knots indicated airspeed. We have found that by keeping the airspeed “alive” while performing any pitot-static sys-tem checks is the only way to ensure the integrity of the instrument as well as provide a visual reference of the applied pressure differential in the system. Calculators. This chart allows a pilot to correct for the discrepancies and calculate the calibrated airspeed (CAS). K and k = 1. The reason is somewhat deeper than just the indication. Of particular interest in this calculator is the Equivalent Airspeed, which is essentially the calculation of IAS that aircraft display as the primary airspeed reading. True Airspeed Calculator. 51 x 104 N/m2 . It is not possible to eliminate all errors, however, many airplanes use an airspeed calibration chart to determine the difference between IAS and CAS. 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. Modern aircraft instrumentation use an Air Data Computer to perform this calculation in real time and display the TAS/Mach reading directly on the Electronic Flight Instrument. At this airspeed, the IAS and CAS are the same due to the AOA and "design" of the pitot tube. To calculate airspeed, we convert the pressure of air that is. which can be. This is simple. You pick the power setting (RPM) that gives you the range/performance you want, then you set the throttle to that setting in flight. Airspeed Exercise Part 1 document). [In straight flight]: Assume that wind speed is fixed, calculate airspeed from wind speed, ground vector and heading. 3. the minimum-thrust-flight condition provide an accurate prediction within considered airspeed and altitude range. 3. 4 are available for direct Mach number. [ft/s or m/s] Version Information. This is the point of your cross-country p. Add 2 minutes for climb-out. TAS is given in mph. (Dynamic Pressure. There is an aerodynamic instrument that actually measures the total pressure at a point in the. Assume incompressible flow. Calculators Airspeed Conversions (CAS/EAS/TAS/Mach) An airspeed calculator designed to convert between indicated/calibrated airspeed and true air. How to use the true airspeed calculator? Below are tips for using the true airspeed calculator and understanding how it works. This computer, rather than individual instruments, can determine the calibrated airspeed, Mach number, altitude, and altitude trend data from an aircraft's Pitot Static System. Enter CAS, fuel burn rate and cruise power setting in Nav Log. We calculate the heading with the formula: psi = delta + alpha ψ = δ + α. So we can calculate the new ratio as: Letʼs look at the airspeed indica-tor as an example. It receives air pressure information from two different sources and measures a differential between the two, presenting this data as ‘airspeed’. Use equivalent airspeed to calculate true airspeed. True airspeed (TAS) is the speed at which an airplane is moving relative to the air that surrounds it. 1) the following: (a) pressure ratio (b) pressure altitude (c) temperature ratio (d) density. Record the time it takes to climb through the altitude block. and 16 each calibration mark is equal to . Let's say we're flying at 6,500 feet on a day with standard pressure and temperature at sea level. $egingroup$ 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. KNOTS vs. At an altitude of 8000 feet, calculate the cylinder's total lift in pounds. In this case the calibrated airspeed (CAS) (b) was the same as the equivalent airspeed (a). . True airspeed is the reality. 26. What you see on the dial, is the IAS. 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. Calibrated airspeed is specific to the conditions in which the plane is flying, including altitude and temperature, as well as the shape of the aircraft wings. This chart allows a pilot to correct for the discrepancies and calculate the calibrated airspeed (CAS). 00:21. . 7. There's no standard preventing an EAS calculator in the cockpit - indeed some ASIs are designed to do exactly that, and some FMS work out TAS from IAS, via EAS - although I suspect that many of those fail to allow. |. (412TW-PA-12762). For navigation the CAS is the first step to calculate the GS. Equivalent airspeed. Airspeed. E6B, NavLog Calculator, Weather Reports, METAR, TAF, Wind Components, Instrument Simulator, Weight and Balance, Pressure Altitude, Density Altitude, True Air Speed. The more of each, the more lift. IAS figures in aircraft manuals are actually converted from CAS. You need to specify the altitude at which you would like to perform the calculation as well as any one of the four airspeeds . CALCULATE CALIBRATED AIRSPEED GIVEN PRESSURE. If the localizer is swinging one way or the other, then make a 1-2 degree correction to avoid chasing. You can see the true airspeed based on the example calibration tables modeled in the Calculate CAS block. 2 for the density factor, which should actually be 1. CAS is IAS corrected for instrumentation and position errors. Boldmethod. 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. BROWN Aircraft Performance Engineer SEPTEMBER 2012 TECHNICAL INFORMATION HANDBOOK AFFTC-TIH-10-01 Approved for public release; distribution is unlimited. Now I know the formula for calculating airspeed is: SQRT ( (2 * ( Pitot - Static)) / density ) and many sources I find use 1. To climb, add power. 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. 00347. 25 to about 800 hectopascals. 50 lbs/ft2, T = 411. Greg Bajor/Getty Images. 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. Calculate the Mach number at which the airplane is flying. Use the atmoscoesa function to first calculate the speed of sound ( sos) and. 65 × 10 4 N/m 2 at 10 km. Calibrated airspeed is indicated airspeed adjusted for a variety of errors. 4. Density altitude is a condition that affects aircraft performance. TAS cannot be measured directly. Engine, pitch attitude, airspeed, and trim should be stabilized. Calculators. Groundspeed is true airspeed corrected for wind. It implicitly includes air density and thus altitude). Keep a coordinated turn (ball centered). 6. If the ambient air temperature is 230 K. MH (Compass deviation card) Cruise Performance 5-20. An air data system provides calculations of flight variables, including calibrated airspeed, true airspeed, equivalent airspeed, Mach number, free-stream static pressure and outside air temperature, air density, pressure altitude, density altitude, angle of attack, and side slip angle. Indicated airspeed is measured using the pitot-static system. Any initial heading will do so long as the turns are 90 degrees and in the same direction. Calibrated airspeed (CAS) is calculated from IAS and correcting it for measurement errors. The true airspeed (TAS; also KTAS, for knots true airspeed) of an aircraft is the speed. 225 = 68. KTAS is true airspeed given in knots. Do it with both light weights and with heavy weights. So, at 10,000 feet, true airspeed is roughly “T ratio – Mach Number relationship”. 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. True airspeed is calibrated airspeed corrected for non-standard atmospheric pressure and temperature. It’s n=V 2 / V S 2, where V is the calibrated airspeed at the start of the maneuver. The calculator side of the flight computer is constructed so that any relationship, or ratio, between a number on the outer scale and a number on the inner scale will remain. Knots Indicated Airspeed: This is the airspeed (in knots) directly calculated from the air pressure inside the pitot probe of aircraft and it represents the speed of airflow as the aircraft travels through the air. By flying three different headings and mathematically crunching the geometry, we can precisely determine both the speed and. How exactly does a G1000 system equipped with a GDC 74 air data computer calculate the indicated airspeed that is displayed on the PFD from difference between the total and static pressure. . 92 in the altmeter. CAS is IAS corrected for instrument and position errors. One of the difficulties in using GPS speeds to calculate airspeed is the effect of wind. [2] This is the pilots' primary airspeed reference. Calibrated Airspeed for each test altitude. — Profile Valid: This allows you to set your profile On or Off once all data is entered . But calibrating your ASI is quick and easy using a handheld GPS. None of the choices 1290. They are also resticted to only subsonic speeds. Rotate the inner scale until the numbers on the inner and outer scales match. = ( 𝑀 + 1) 𝑃1 2. This used to be a much bigger deal when flights were conducted by dead reckoning, and reliable airspeeds were more directly beneficial to the flight planning and enroute. ground speed section above to learn more about the differences between the two. It’s calibrated speed adjusted for altitude and non-standard air. MACH NUMBER (M) “P ratio – Mach Number relationship”. At an altitude of 8000 feet, calculate the cylinder's total lift in pounds. Airspeed indicator itself. The old ratio was 2. When the air density or. 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. This formula provides an estimate based on altitude. It’s the aircraft speed relative to the airmass in which it’s flying. PLANNED TRUE AIRSPEED. For example - assume a flight plan with following checkpoint information:. Step 3: Fill in the wind speed. KCAS (Knots Calibrated Airspeed) Like KIAS, but corrected for instrumentational or positional errors. With this example you can calculate the change for your situation. Calibrated airspeed is indicated airspeed adjusted for a variety of errors. It is set to a default value of 1 . We set the power as desired for takeoff, cruise, descent, or landing. 3. The formula used to calculate a safe speed for a lower weight is , where V A is maneuvering speed (at maximum weight), W 2 is actual weight, W 1 is maximum weight. com) On one hand the probe, depending on its location, could measure the pressure in the free stream, in the high velocity stream, or in the low velocity stream. For ease.