Why don't people know the difference between True Airspeed, and Indicated Airspeed...RANT

TheGolfPilot

TheGolfPilot

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Yesterday I was talking to a guy with a Turbo 182RG. He asked me how fast my Archer cruised. I told him it trues out at 125 at 75% power. His response "wow you must get a lot of tailwinds because my T-182RG only gets 140 knots, with a tailwind my gps will show 160-170". That aggravated me to poke some more. He really, truly, didn't understand the concept of what True airspeed was, what it is, and how that is useful. He was an older guy who has likely been flying for decades. And it doesn't end there, its hard to hold a conversation with most people about speeds of planes because the numbers always come out different. Some people will say indicated speeds, some will say ground, some will say True and very rarely do they understand which one they are referring too. I have even seen a guy pitch for Vy using his 650!!!! We had a tailwind, and he was complaining about climbing really slow. Are you kidding me, you are going to kill us, push the nose down!!!!!! Is this a localized issue or are people everywhere this ignorant?
 
Things like that don't bother me. And I get where someone can confuse TAS with groundspeed in casual conversation.

Actually, I try not to pay much attention to other pilots anyway because if you let it, there's an awful lot of BS that could irritate you.
 
I mean...I understand why folks would get confused. My airplane has the true airspeed ring on it so I can set the altitude and temp and get TAS, but I never use it to be honest. You could also do a quick E6B calc in the air to get it, but most people don't do that much ha.

The newer planes with glass panels usually automatically calculate it and show you all three, indicated, ground, and TAS, which is nice.
 
Also can be a notable difference or not depending on the plane, low level cub, IAS vs TAS is just a rounding error, turbine in the FLs that's a different story.

Though not getting the difference between IAS and GS is pretty bad.
 
TheGolfPilot said:
Yesterday I was talking to a guy with a Turbo 182RG. He asked me how fast my Archer cruised. I told him it trues out at 125 at 75% power. His response "wow you must get a lot of tailwinds because my T-182RG only gets 140 knots, with a tailwind my gps will show 160-170". That aggravated me to poke some more. He really, truly, didn't understand the concept of what True airspeed was, what it is, and how that is useful. He was an older guy who has likely been flying for decades. And it doesn't end there, its hard to hold a conversation with most people about speeds of planes because the numbers always come out different. Some people will say indicated speeds, some will say ground, some will say True and very rarely do they understand which one they are referring too. I have even seen a guy pitch for Vy using his 650!!!! We had a tailwind, and he was complaining about climbing really slow. Are you kidding me, you are going to kill us, push the nose down!!!!!! Is this a localized issue or are people everywhere this ignorant?
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Confusing True with Ground speeds is one thing. Confusing Ground with Indicated and judging Vspeeds is another. That ain't good
 
Clark1961 said:
Clearly another training video is needed.
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The Grumman obviously doesn't have what trombonists refer to as "true airspeed" otherwise they would have given you an altimeter similar to this one in the Cirrus.
 
SixPapaCharlie said:
Because it is complicated?
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Clark1961 said:
Clearly another training video is needed.
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IAS = the number that shows up on your airspeed indicator. It's proportional to your speed relative to the airmass you are currently occupying, but is affected by altitude.

TAS - Your actual speed through the airmass you are currently occupying

Groundspeed - The speed of your aircraft relative to the ground. It is the combination of TAS plus or minus any tail or head wind.

See, not so scary.
 
FormerHangie said:
IAS = the number that shows up on your airspeed indicator. It's proportional to your speed relative to the airmass you are currently occupying, but is affected by altitude.

TAS - Your actual speed through the airmass you are currently occupying

Groundspeed - The speed of your aircraft relative to the ground. It is the combination of TAS plus or minus any tail or head wind.

See, not so scary.
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Just wait until you see the 6PC training video. He'll git ya straightened out fer sure and fer certain.
 
SixPapaCharlie said:
The Grumman obviously doesn't have what trombonists refer to as "true airspeed" otherwise they would have given you an altimeter similar to this one in the Cirrus.
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What about the ukulele player?
 
I’ve actually observed that as well. Seen it both in the Army and civ flying. At several thousand feet up, “Oh, ground speed is 6 kts more that our airspeed. Getting a descent tailwind.”

I attribute it to pilots just never fully understanding it in training and then later on, completely dumping it. Knew guys that had no clue that our aircraft (UH-60) had significant instrument error at both high and low indicated speeds. Had no idea why it has the instrument error as well.

I don’t get all fired up over that stuff though. Known plenty of pilots that were very weak on aerodynamics. As an IP I had to spoon feed it to a lot of pilots, only to have them dump that months later. I would say to myself, well they’ll always be a strong pilot assigned to them make up for their inadequacies...either that or an AOA indicator. :D
 
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To be honest, I really don't worry about it. The aircraft is going to go as fast as its going to go. The only time I really worry about how fast I'm going is taking off and landing, to stay well away from adverse events. I suppose there's a good mathematic way to derive TAS, but what exactly is that going to do for me?

I do keep an eye on IAS, because that can tell me if there's something wrong with the aircraft.
 
Pilawt said:
Ah for the days when you knew Vy was when the wind in the wires was sounding F# over middle C ...

:p
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That's why they changed from the whisper test 10 or 15 years ago on your medical...you no longer have to be able to hear those things.
 
steingar said:
To be honest, I really don't worry about it. The aircraft is going to go as fast as its going to go. The only time I really worry about how fast I'm going is taking off and landing, to stay well away from adverse events. I suppose there's a good mathematic way to derive TAS, but what exactly is that going to do for me?

I do keep an eye on IAS, because that can tell me if there's something wrong with the aircraft.
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IAS is important because that what the aircraft "feels". If your stall speed is 50 kts and and IAS is 55 kts, things are going to get mushy, regardless of TAS. Back in the bad old days, before all these newfangled devices, TAS was important because you could use it to deduce winds aloft, which was important when using pilotage :yikes: or dead reckoning to navigate. Now like @Bill Jennings said, TAS is mostly used for bragging rights.
 
Yeah, your buddy definitely had it all wrong. Here's how you straighten it out to him.

Ground speed is the speed of all them trucks on the ground. Indicated airspeed is the speed of the airplanes in Indy. Since I ain't from Indy and all that stuff in the Gee Pee Ess is fake I go by true airspeed. Now the way to remember it is if them trucks on the ground are faster then ground speed is higher and you have a head wind. To double check, open a window and see whether you feel the wind on your head or on your tail.
 
Timbeck2 said:
I own a Cherokee. I have nothing to brag about when it comes to calculating true airspeed because when the math is over, it would be depressing leaving me mentally tired and depressed.
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Trade it in for an RV-7 already! Probably not even using your back seats on that thing.
 
FormerHangie said:
IAS is important because that what the aircraft "feels". If your stall speed is 50 kts and and IAS is 55 kts, things are going to get mushy, regardless of TAS. Back in the bad old days, before all these newfangled devices, TAS was important because you could use it to deduce winds aloft, which was important when using pilotage :yikes: or dead reckoning to navigate. Now like @Bill Jennings said, TAS is mostly used for bragging rights.
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TAS doesn't do a damn thing to help you in pilotage. What you want is groundspeed, which you calculate by time to waypoints. Once you know your ground speed you know how fast you're going to get to your next waypoint. Although groundspeed is TAS plus winds aloft, in reality the only number you need is how fast you're going. If you're going by dead reckoning its the same, you need direction and groundspeed. I have to admit, if you really are using dead reckoning then TAS might be a good thing, since winds can shift en route. How you calculate TAS without some sort of external reference is beyond me, and if you're using an external reference then you really aren't navigating by dead reckoning.
 
Since I only fly IFR ( I Follow Roads) Ground speed is based on passing trucks on the interstate... If they are passing me, not good, if I'm passing them, good.... ( the magenta line on GP is helping change that) IAS changes so much based on under the clouds being pulled up or down, and how much bumps are around it mostly just keeps changing... and having an old Cherokee, everything is in MPH so it sounds great... "was doing 155 yesterday"... sure beats saying gets along at 135k's...

A few weeks ago I did see 160 mph IAS and the trusty E6b showed 179 TAS... @8000 ft full throttle.. max power....57 deg F, yes, level flight. sure love my old hot rod 140... ( 28 gal fuel and just me along for the ride.. light and fast! )
 
TheGolfPilot said:
are people everywhere this ignorant?
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Yes. They're idiots.

I never had a problem with these concepts, maybe because I spent a lot of time on boats growing up so the difference in the GPS speed vs the knot indicator was always different as a result of currents, etc. TAS vs IAS I can sort of understand why it would confuse people... but really, anyone with a basic understanding of air density shouldn't be stumped by it. The "true" airspeed is just that, the true, actual airspeed of the playing moving past the air molecules around it. IAS is just what it "feels" like to the plane because there are fewer air molecules as the air gets less dense..

It is true that in the lower altitudes many of us fly at the difference in IAS vs TAS is relatively small.. but it is still there. In the Archer I'll often play with the little ring thing, then use the 650's utilities page to calculate the TAS to see the difference
 
steingar said:
TAS doesn't do a damn thing to help you in pilotage. What you want is groundspeed, which you calculate by time to waypoints. Once you know your ground speed you know how fast you're going to get to your next waypoint. Although groundspeed is TAS plus winds aloft, in reality the only number you need is how fast you're going. If you're going by dead reckoning its the same, you need direction and groundspeed. I have to admit, if you really are using dead reckoning then TAS might be a good thing, since winds can shift en route. How you calculate TAS without some sort of external reference is beyond me, and if you're using an external reference then you really aren't navigating by dead reckoning.
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The way you calculate TAS given IAS is to apply a correction factor.

Like I said, if you know your TAS and your groundspeed isn't what you expect, then the winds are different than what you thought they were, and you may very well have to change your heading, so yes, it is relevant to those who are doing pilotage or DR.
 
steingar said:
If you're going by dead reckoning its the same, you need direction and groundspeed.
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How do you calculate crosswind correction without TAS?

How you calculate TAS without some sort of external reference is beyond me, and if you're using an external reference then you really aren't navigating by dead reckoning.
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What do you need to calculate TAS besides CAS, OAT and pressure altitude?
 
Glenn D said:
Since I only fly IFR ( I Follow Roads) Ground speed is based on passing trucks on the interstate... If they are passing me, not good, if I'm passing them, good.... ( the magenta line on GP is helping change that) IAS changes so much based on under the clouds being pulled up or down, and how much bumps are around it mostly just keeps changing... and having an old Cherokee, everything is in MPH so it sounds great... "was doing 155 yesterday"... sure beats saying gets along at 135k's...

A few weeks ago I did see 160 mph IAS and the trusty E6b showed 179 TAS... @8000 ft full throttle.. max power....57 deg F, yes, level flight. sure love my old hot rod 140... ( 28 gal fuel and just me along for the ride.. light and fast! )
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Mine got up to the yellow line, straight and level with me and a 265 lb passenger last Saturday. Gotta love flying in winter.
 
Tantalum said:
Yes. They're idiots.

I never had a problem with these concepts, maybe because I spent a lot of time on boats growing up so the difference in the GPS speed vs the knot indicator was always different as a result of currents, etc. TAS vs IAS I can sort of understand why it would confuse people... but really, anyone with a basic understanding of air density shouldn't be stumped by it. The "true" airspeed is just that, the true, actual airspeed of the playing moving past the air molecules around it. IAS is just what it "feels" like to the plane because there are fewer air molecules as the air gets dense..

It is true that in the lower altitudes many of us fly at the difference in IAS vs TAS is relatively small.. but it is still there. In the Archer I'll often play with the little ring thing, then use the 650's utilities page to calculate the TAS to see the difference
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I like to use the little ring thing. Totally forgot the GTN has that utility, will be playing with that next flight!
 
steingar said:
TAS doesn't do a damn thing
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Everything starts with TAS.. your GS is just your TAS with the winds factored in. Every flight plan I make starts with TAS and then I factor in the winds to get the GS, then times, fuel, etc. TAS is arguably the most critical thing since most of the calculations branch from there

steingar said:
How you calculate TAS without some sort of external reference is beyond me
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Most planes I've flown had a ring you can turn on the IAS where you put in your altitude and temp and it tells you your TAS. Or, if you don't have that little turning ring just use your E6B.. or some electronic version of it on the ipad

*Calculating TAS is important to know the overall health of your plane, etc. For example, if you know you should be getting 125 knots at a certain power/RPM setting and you are actually getting 117 knots TAS you know that maybe you left your gear out (!) or you have some other issues with your prop or power settings, etc. TAS is a key data point
 
Tantalum said:
In all honestly though I only use the one on the GTN when I get bored since the ring is so fast and easy to use
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After you get TAS you can enter your heading and get wind aloft, then you can submit your PIREP like a real pro. ;)
 
FormerHangie said:
IAS = the number that shows up on your airspeed indicator. It's proportional to your speed relative to the airmass you are currently occupying, but is affected by altitude.

TAS - Your actual speed through the airmass you are currently occupying

Groundspeed - The speed of your aircraft relative to the ground. It is the combination of TAS plus or minus any tail or head wind.

See, not so scary.
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Until you need a Vx climb to get over some stuff in a brisk wind and you are doing it using the Ground Speed on your Gucci whizbang glass gadget instead of IAS
 
luvflyin said:
Until you need a Vx climb to get over some stuff in a brisk wind and you are doing it using the Ground Speed on your Gucci whizbang glass gadget instead of IAS
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The Gucci 1000 is usually set up so that GS is outside most people's scan. It also has Vx plainly marked on the IAS tape. The Gucci 430 is rarely centered in front of the pilot. I have a hard time believing someone flying a Gucci 430/530/650/750/1000 would use GS for Vx.
 
Tantalum said:
*Calculating TAS is important to know the overall health of your plane, etc. For example, if you know you should be getting 125 knots at a certain power/RPM setting and you are actually getting 117 knots TAS you know that maybe you left your gear out (!) or you have some other issues with your prop or power settings, etc. TAS is a key data point
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That's what IAS is there for. If you honestly know what your airplane should be doing, you should be able to spot something wrong using the indicated airspeed. You don't need math to tell if your gear is hanging out or you let the damn door open. It really isn't that difficult.
 
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