Speed Definitions and Calculations ✈ IAS CAS EAS TAS GS MACH

[@Pilot_Natan]

Teachers like you and I would have 3 degrees by now. You’re funny, precise and simple. Great job captain!

[@mariuscostel5218]

You saved me in my PPL navigation calculations. And now you are saving me in my ATPL exams. Thank you Ed!!

[@Barabyk]

That was so much better than any CBT I came across so far!

[@emmanuelpico8920]

AMAZING WAY TO EXPLAIN, so easy to understand, thank you so much. you got all my support. have good winds.

[@PilotEd]

cheers

[@Wierdwires]

Your explanation on speeds concept is crystal clear. I’m not sure where I missed going into/during the calculation. Why use IAS in calculation which contain layers of error ? Or in this example IAS = EAS ? I’m pilot student on Cessna 172.. I should use CAS in the formula as the error from compression is negligible right ?

[@benedictusaryasatya6761]

Finally get the answer of how to get TAS fros IAS.. save it for tomorrow in case my FI ask me before get to my night xcountry tomorrow haha... thx so much mate godspeed

[@CommandT]

First!!!!!!!!!!!!!!!!!!!!!!!!

[@PilotEd]

:)

[@JoeRichardson02]

These videos are great, very helpful!

[@PilotEd]

welcome :)

[@ogulcan1559]

Thank you Captain!

[@tomaszfelczak7211]

Great video as always. Very helpful chanel during ATPL theory stage... Kind regards

[@PilotEd]

thanks for watching mate!

[@julianburton5333]

Hi Ed, hoping you can point me in the right direction to where i can get the bag you had in a previous video

[@ShadowRap-y5l]

Why did you stop? Your videos are awesome!

[@Abhinav-uu8hp]

Thanks for the amazing video Captain. Doing my CPL theory in India, I think there is another simple formula for calculating TAS. It is [TAS= Mach Number* (38.95 * √K)] where K is the temp in Kelvin.

[@PilotEd]

cool, didn't know that one, test it with my snapshot in the video and post the result :) call it -50degrees C

[@Abhinav-uu8hp]

@emmanuel kapoor Yes it's exactly the same. Mach number is TAS/LSS

[@gbanderas2479]

yes, i also used that one. its actually the same as the above formula just simplified: 661/sqrt288=38,95! ;) Nice job PilotEd, helped me a lot through my ATPL theories!

[@ShadowRap-y5l]

Are you a pilot now?

[@anikbhowmick1044]

sir please take that temperaure 218K .it will give acurate value . but excellent explanation . I am not a pilot .but study aviation stuffs from childhood . airspeed has been a long doubt for me .finally got clear

[@igp3378]

I like it! Thank you!

[@conned]

Love it

[@rigilchrist]

Good summary. BTW a *tiny* point: Pitot is pronounced without sounding the last letter, ie "pito".

[@mirkocirillo736]

Thanks for your job. Very appreciate it!

[@PilotEd]

thanks for watching :)

[@reiramessi]

So u fly 737 800 ng ?

[@PilotEd]

when im not making youtube videos haha

[@jeddidiahmalachai7436]

Wouldnt it be 661x.77x(square root of .9? I think u left out the square root part.

[@VehicleVillains]

Second.

[@PilotEd]

haha sucker! get there sooner next time! what you make of my advanced editing haha

[@VehicleVillains]

@@PilotEd I was kinda hoping to see some animations of birds getting obliterated by pitot tubes :P P.S. The 'First' is also me. Ha!

[@piers4130]

This video presents a wrong explanation of compressibility error. There is no "flow of air through" a Pitot tube. A Pitot tube is a closed tube terminating at the airspeed indicator capsule (or air data module in modern aircraft). The purpose of a Pitot tube is to measure the total (stagnation) pressure. The mouth of the Pitot tube is a stagnation point. A stagnation point is a point in the airflow where the flow is locally brought to rest. Therefore in steady flow air is not "taken in" to a Pitot tube. When compressibility error is present the airspeed reading will be higher, not lower. CAS will be greater than EAS. The video fails to explain why an airspeed indicator does not exhibit compressibility error at ISA sea level, even at high Mach number. Since the Mach meter is also connected to a Pitot tube, a student who heard this explanation might conclude that the Mach meter would also exhibit compressibility error. However a Mach meter does not exhibit compressibility error at any altitude.

[@andreaappiani7799]

Hi Ortac, I spotted the same error in this video. EAS is actually lower than CAS, because the density "measured" at the pitot would be greater due to compressibility effect. However, could you explain why an airspeed indicator does not exhibit compressibility error at ISA sea level? I am not getting it... Thank you!

[@piers4130]

@@andreaappiani7799 It comes down to the way the mechanical ASI is calibrated. EAS would be the "ideal" airspeed to present to the pilot because EAS is directly related to dynamic pressure and hence aerodynamic forces. Anything which causes the ASI to read other than EAS is therefore considered a cause of error and should be minimized as far as possible. The equation used to calibrate the ASI correctly accounts for compressibility at ISA sea level and thus under this condition CAS = EAS (no compressibility error). However a mechanical ASI knows only the differential pressure (total - static). It does not know the absolute static pressure and therefore can be calibrated only for one static pressure (by convention, ISA sea level) . The relation between EAS and compressibility varies with static pressure (i.e. altitude). The calibration equation correctly accounts for compressibility only at ISA sea level. When the ASI is used at high altitude there will be a compressibility error because the calibration equation does not correctly account for compressibility at high altitude. A modern air data computer knows the absolute static pressure and could therefore easily output EAS at all altitudes. The speed tapes on modern PFDs show CAS but this is only because of historical convention. More logically they would show EAS.

[@andreaappiani7799]

@@piers4130 thank you very much sir, extremely clear explanation. This is the kind of stuff I would like to read on an ATPL book...!