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

I’m convinced some people in this thread don’t know the difference.
 
so....to quote a famous female...."What difference does it make....?"
 
Am I a slacker? Caring not a nit about TAS or CAS in my 172? I give a good bit of attention to IAS . . .oh, once, when bored on a long x-ctry, I did calculate my Mach.
 
Sundancer said:
Am I a slacker? Caring not a nit about TAS or CAS in my 172? I give a good bit of attention to IAS . . .oh, once, when bored on a long x-ctry, I did calculate my Mach.
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Lol!!! .12 ??
 
MauleSkinner said:
Great, you know the DA is 10,382.43 feet...what does that mean for this airplane today in terms of takeoff and climb performance? Especially if your charts don't go that high?
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Ive seen it high enough that thecruise performance charts worked. Also the cruise power charts will give a good hint on what your actual takeoff power will be in a normally aspirated engine. As in, “oh look, the engine will only be making 65% of rated power for the takeoff roll today worsening to pattern altitude...”
 
Sundancer said:
Am I a slacker? Caring not a nit about TAS or CAS in my 172? I give a good bit of attention to IAS . . .oh, once, when bored on a long x-ctry, I did calculate my Mach.
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You are not a slacker. When TAS makes a difference in flying is...well, it doesn't. In cruise the airplane will go how fast it goes. On an XC I am more concerned with ground speed and ETE than TAS. When landing, the airplane will stall when it stalls. I have no idea what my IAS is because I have never looked at my speed when landing. On takeoff it does nothing because the airplane will fly when it flies and a glance at the IAS tells me if I need to abort. The airplanes 95% of us fly have an IAS/TAS difference less than the margin of error of reading the ASI.

True, TAS is the aerodynamic speed of the wind. An airpane designer cares about it. As a pilot it does nothing for me, kind of like the ADF questions on the written test.
 
Since I’m studying for the IR written AGAIN (I’m not bitter!), if you don’t bother with TAS, how do you file annIR plan and how do you know when your TAS is going to vary more than 10% (required report to ATC when IFR)?
 
jsstevens said:
Since I’m studying for the IR written AGAIN (I’m not bitter!), if you don’t bother with TAS, how do you file annIR plan and how do you know when your TAS is going to vary more than 10% (required report to ATC when IFR)?
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I doubt most worry with it.....o_O
 
bflynn said:
The airplanes 95% of us fly have an IAS/TAS difference less than the margin of error of reading the ASI.
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If the margin of error reading your ASI is upwards of 15%, I'd suggest getting it or your eyes fixed.
 
MauleSkinner said:
From what I've seen here, DA calculations are merely a placebo...they do nothing towards actually knowing your aircraft performance, but makes you feel better because you calculated a number.

Great, you know the DA is 10,382.43 feet...what does that mean for this airplane today in terms of takeoff and climb performance? Especially if your charts don't go that high?
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Are you serious?
 
bflynn said:
When TAS makes a difference in flying is...well, it doesn't.
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When flying by dead reckoning, how do you estimate a crosswind correction without TAS?
 
asicer said:
When flying by dead reckoning, how do you estimate a crosswind correction without TAS?
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The short answer is that I don't estimate a crosswind correction because it's going to be wrong anyway. I crab the plane until I'm tracking toward the target I want to go to. Then I check the ground speed and ETA for fuel. What would I do if both magenta lines died? Probably pull out the paper chart and continue.
 
MauleSkinner said:
If the margin of error reading your ASI is upwards of 15%, I'd suggest getting it or your eyes fixed.
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Great example of why context matters. A 15% difference occurs around 7500'. But at 7500', I'm cruising. I don't care if the TAS is 100, 110 or 125. It just doesn't make any difference to how I fly. Now I do know that if I ever fly west and land at an airport that is 7500', it will affect my stall speed. If/when I get there, I'll check my performance, as I do any time I change one of the variables in my performance equation.
 
Personally, TAS - if available - is what I am mainly concerned with as I fly along, to verify aircraft performance.

It was displayed prominently on the Avidyne PFD in my Cirrus, and is right in front of me on my Dynon D10A in my Sky Arrow (as long as I input OAT).

GS is more of a navigational concern, and of course that's important in its own right.
 
bflynn said:
Now I do know that if I ever fly west and land at an airport that is 7500', it will affect my stall speed.
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It will? I did not know that...:eek::rolleyes:

I've flown in and out of most of the public airports in Colorado, a fair number of the airports in Wyoming and even a half dozen airports in the northernish portion of New Mexico. I've also flown at sea level notably landing at Mustang Island. I've also landed in Houston but found avoiding ANG helos more of a challenge than the stall speed. Can't really say that I noticed a variation in indicated stall speed other than weight of the aircraft. Of course the true airspeed does vary with density altitude so the speed over the ground varies when landing and departing. Of course wind also affects the speed over the ground. I find that wide runways bother me more than changes in true airspeed when landing. I'm sure we're all a little different in our visual perceptions on landing.
 
kayoh190 said:
Without TAS, exactly what number am I going to add 20% to when bragging about the speed of my plane? :)
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That's easy, add 20% to the one you make up while you decrease the fuel burn by 50%. I thought this was common knowledge for all Bonanza and Mooney owners.
 
Clark1961 said:
That's easy, add 20% to the one you make up while you decrease the fuel burn by 50%. I thought this was common knowledge for all Bonanza and Mooney owners.
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Nah, 10% and 10%, gotta make it somewhat believable.
 
Seriously fellas, if we're ever at a meet up and I ask what your airplane trues at, you have my permission to punch me in the mouth and send me back to the hotel. True airspeed is like schlong size, it only matters to you.
 
Timbeck2 said:
Seriously fellas, if we're ever at a meet up and I ask what your airplane trues at, you have my permission to punch me in the mouth and send me back to the hotel. True airspeed is like schlong size, it only matters to you.
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I'd just make up a number....bigger than yours. How's 195 kts sound? ;)
 
bflynn said:
The short answer is that I don't estimate a crosswind correction because it's going to be wrong anyway. I crab the plane until I'm tracking toward the target I want to go to. Then I check the ground speed and ETA for fuel. What would I do if both magenta lines died? Probably pull out the paper chart and continue.
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Great. Not only do people not know the difference between TAS and IAS, we also have people that don't know the difference between pilotage and dead reckoning.
 
FastEddieB said:
To clarify, what is the “it” that you’re referring to?
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Good question - I was thinking TAS because it diverges more from IAS as altitude increases, but the altitude itself has a big impact too, maybe bigger. But as I'm a flatlander and usually fly the same equipment out airports with runways much longer than minimums, carrying myself and 2/3 of a tank of gas, it doesn't matter much to me what "it" is. If/when I plan a flight where this matters, I'll stop and consider it.

Meanwhile, the airplane flies whether I know the TAS it's flying at or not.
 
SoCal RV Flyer said:
Common practice is ground speed (with a healthy tailwind)...plus 20%. :D
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This. My PA-28-161 hit 156 kts last month...oops, plus 20%, I meant 187.2. That is one smoking airplane, I'm loving it the fast speeds.

We won't talk about the 70 kts I had going there though...
 
asicer said:
Great. Not only do people not know the difference between TAS and IAS, we also have people that don't know the difference between pilotage and dead reckoning.
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Who?

Did you not understand that when I said I crabbed the airplane to reach a destination, this works for both landmarks and bearings? I get a ground course off the same source as I get the magenta line - the GPS and Foreflight. If they both die, I pull out a map and fall back to pilotage.

I was a sailor long before I was an aviator. There are very few landmarks on the ocean, I get dead reckoning. How do you accomplish it on the sea? You sail so your track is going in the direction you want. But no matter how good your boat is, you're going to get downwind drift, so your heading isn't the same as your course heading. You're always crabbing at least a little in sailing. Unless there's no wind and then you're not sailing, you're drifting.

How about you quit trying to prove that you're the better aviator and we all just go fly. It's a beautiful day, at least here...
 
bflynn said:
Good question...
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Was not sure where you were coming from, but as an oral “springboard for discussion”, I may ask...

“Let’s say at sea level you approach at 55kias. If you were in Denver on a hot day, how might you adjust that?”

More than a few pilots stumble on that one.
 
FastEddieB said:
Was not sure where you were coming from, but as an oral “springboard for discussion”, I may ask...

“Let’s say at sea level you approach at 55kias. If you were in Denver on a hot day, how might you adjust that?”

More than a few pilots stumble on that one.
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You don't.
 
FastEddieB said:
Was not sure where you were coming from, but as an oral “springboard for discussion”, I may ask...

“Let’s say at sea level you approach at 55kias. If you were in Denver on a hot day, how might you adjust that?”

More than a few pilots stumble on that one.
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Which is really a misleading question since approach indicated airspeed is not adjusted for altitude. Where folks should be lead is towards mixture setting and how that should be adjusted along with required runway length. Of course out here in the land of long runways length usually isn't a problem except at a few airports...and for a few aircraft which require long runways...anyway, it's something to be aware of...and I have rolled out about 6,000 ft downhill and downwind (don't ask).
 
Flying was gorgeous, 6000 ovc, calm winds and only 4 kts at 3000’. Complete ego air, so I was about +50’ on both left and right steep turns, a little high on the engine out and nailed three short field landings, exiting at the taxiway 1000’ down the runway. Not bad for not having flown in 45 days.
 
Clark1961 said:
Which is really a misleading question...
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I like to think of it as "probing" rather than misleading.

If the pilot/student answers, "No adjustment that I know of - you use the same IAS regardless of altitude or temperature.", then I say, "Good" and move on to the next area.

If he or she says he would use either a higher or lower IAS, then we need to delve into the topic a bit more.
 
MauleSkinner said:
Yes.
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In that case I’m not sure where to start.

Knowing density altitude is essential for flight planning purposes at high altitude airports and can also be a factor at lower altitude airports if they are short enough. To me when you say that knowing the density altitude is not important would be the same attitude and poor decision making as someone saying it’s not important to know how much gas is onboard. You should rethink your attitude regarding DA and perhaps spend some time talking to a pilot that can show you how much benefit can be gained in your airmanship skills by incorporating it in your flying. If you only fly sea level airports in a plane that’s always well below gross from long runways suitable for jets then perhaps you can get away with not understand and using DA info. In other circumstances it’s critical information.
 
bflynn said:
Great example of why context matters. A 15% difference occurs around 7500'. But at 7500', I'm cruising. I don't care if the TAS is 100, 110 or 125. It just doesn't make any difference to how I fly. Now I do know that if I ever fly west and land at an airport that is 7500', it will affect my stall speed. If/when I get there, I'll check my performance, as I do any time I change one of the variables in my performance equation.
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How will it affect your stall speed?
 
FastEddieB said:
I like to think of it as "probing" rather than misleading.

If the pilot/student answers, "No adjustment that I know of - you use the same IAS regardless of altitude or temperature.", then I say, "Good" and move on to the next area.

If he or she says he would use either a higher or lower IAS, then we need to delve into the topic a bit more.
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I'm of the mindset that probing is not teaching. Probing immediately sets up potential for conflict which is a negative environment for learning. In my opinion the teachers job is to present material and learn about the student while they are presenting. Then again everyone has their own methods.
 
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