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

[eman1200]

IAS = Internet Air Speed, or the speed reported to your buddies on the internet. also known as "the fastest ground speed my plane has ever gone with the biggest tailwind". that's how fast my plane is. yup.

 

[asicer]

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.

Except IAS is affected by DA. On a really cold day IAS could be higher than TAS. On a really hot day IAS could be a lot lower than TAS.

 

[Pilawt]

For that matter you don’t even need numbers on the ASI to fly the airplane — where is the needle pointing relative to the colored arcs? The IAS numbers are relevant to some airspace regs, and might be of interest to ATC for spacing, and as one factor in calculating TAS; otherwise they don’t mean much.

 

[asicer]

IAS = Internet Air Speed, or the speed reported to your buddies on the internet. also known as "the fastest ground speed my plane has ever gone with the biggest tailwind". that's how fast my plane is. yup.

CAS = Cali airspeed. California is very left leaning so be careful you don't end up in a spin when using CAS.

 

[denverpilot]

Clearly another training video is needed.

One about the colored circles on the ASI? Youtube is ON it. Heh.

 

[luvflyin]

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.

Yeah. The OP mentioned someone he was flying with was doing it with a 650. I'd guess someone doing that doesn't happen often

 

[Hank S]

After you get TAS you can enter your heading and get wind aloft, then you can submit your PIREP like a real pro.

Nah, put it all in and get everything at once.



But I just add 2% per thousand feet, or in this case

130 + 11% = 130 + 13 + 1 = 144 knots.

Easy peasy.

 

[PaulS]

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.

That sounded an awful lot like science, I'm willing to bet you need math to figure those things out, or an expensive gismo.

 

[WannFly]

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.

U missed the CAS

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[GRG55]

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.

What!?! A Mooniac that is NOT obsessed with airspeed?
Heresy. That's what it is.
Shame on you for carrying on like some common Piper or Cessna owner.

 

[aftCG]

I calculate TAS often when I'm on a XC and wish I was going a few knots faster and need to feel better about my choice of planes.

That is hilarious that guy thought he was getting a tailwind everywhere he went. I've had maybe two trips ever where I got a nice push

 

[WannFly]

If u really want jaw dropping speed from archer, just convert the highest one (ground, TAS, IAS, CAS) into kilometers per hr

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[Clark1961]

If u really want jaw dropping speed from archer, fly a cub for awhile

FTFY

 

[GRG55]

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?

Whatever you do, do NOT engage any of these people in a discussion of Indicated Altitude, Pressure Altitude, Density Altitude and True Altitude. Their heads will explode leaving you with an expensive dry cleaning bill.

 

[Hank S]

I calculate TAS often when I'm on a XC and wish I was going a few knots faster and need to feel better about my choice of planes.

That is hilarious that guy thought he was getting a tailwind everywhere he went. I've had maybe two trips ever where I got a nice push

According to my Owners Manual, my plane should cruise ~165mph = 143 knots.

My level cruise groundspeed range in the ten years I've owned my Mooney is 68-186 knots = 78-214 mph. So a lot more headwind (75 knots) than tailwind (43 knots). I just don't believe this is at all unusual for the altitudes we fly without turbocharging.

 

[Pilawt]

I'm willing to bet you need math to figure those things out, or an expensive gismo.

Nah, just $12.95 from Sporty's. Plus shipping.

 

[cowman]

My airspeed indicator has one of the little built in scales where you can line up your pressure altitude with your temperature and see the TAS under the IAS. It's a neat party trick but honestly, at least for the sort of flying I do, it's not a terribly useful number. The numbers I need to know are IAS for basically all things relating to V speeds and Ground Speed for actual navigation which is simply displayed on the GPS.

Seriously though, how can you be a pilot and not know about TAS? Isn't that on the test to become a pilot?

 

[Possum]

Calculator:

http://indoavis.co.id/main/tas.html

or

TAS = IAS + 2% per 1000' altitude

 

[LongRoadBob]

U missed the CAS

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I really am not understanding how this could be. We have it on the exams, IAS->CAS->TAS (last step using calculation for DA). The flight plan sheets I've seen even have boxes for converting don't they? So you show all calculations?

 

[Hank S]

I really am not understanding how this could be. We have it on the exams, IAS->CAS->TAS (last step using calculation for DA). The flight plan sheets I've seen even have boxes for converting don't they? So you show all calculations?

What, you mean this? At cruise speed, it's neglible, and there really aren't any "calculations" from IAS => CAS. Then add 2% to IAS for every 1000' shown on your altimeter.

 

[Checkout_my_Six]

only one thing matters.....GPS speed.

 

[WannFly]

I really am not understanding how this could be. We have it on the exams, IAS->CAS->TAS (last step using calculation for DA). The flight plan sheets I've seen even have boxes for converting don't they? So you show all calculations?

I doubt these people ever calculate DA following their checkride or look at a flat plan

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[steingar]

What!?! A Mooniac that is NOT obsessed with airspeed?
Heresy. That's what it is.
Shame on you for carrying on like some common Piper or Cessna owner.

Don't need to worry about speed because I fly a Mooney.

 

[MauleSkinner]

I doubt these people ever calculate DA following their checkride or look at a flat plan

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I haven't calculated an airport density altitude since my private pilot checkride in 1983. It's pretty much useless for the airplanes I've flown. The airplanes that have performance charts take that into account without a separate calculation, and the ones that done have performance charts don't benefit from it.

 

[asicer]

I haven't calculated an airport density altitude since my private pilot checkride in 1983. It's pretty much useless for the airplanes I've flown. The airplanes that have performance charts take that into account without a separate calculation, and the ones that done have performance charts don't benefit from it.

I want to calculate DA wherever high DA is a concern at an airport. However, every airport I've been where that's a concern states it on ATIS/AWOS and/or has an electronic sign on the taxiway with the DA. Therefore, I'm in the same boat as you with regards to never actually doing the calculation since my checkride.

 

[MauleSkinner]

I want to calculate DA wherever high DA is a concern at an airport. However, every airport I've been where that's a concern states it on ATIS/AWOS and/or has an electronic sign on the taxiway with the DA. Therefore, I'm in the same boat as you with regards to never actually doing the calculation since my checkride.

What do you do with DA once you know what it is?

 

[Clark1961]

What do you do with DA once you know what it is?

Say something like: glad I bought a turbocharged aircraft cause the density altitude is 10,000 feet at 10 a.m.

 

[MauleSkinner]

Say something like: glad I bought a turbocharged aircraft cause the density altitude is 10,000 feet at 10 a.m.

Turbocharged or not, as I said earlier, I've never used DA for performance planning. I'm trying to figure out a reason to actually calculate an airport's DA.

 

[Clark1961]

Turbocharged or not, as I said earlier, I've never used DA for performance planning. I'm trying to figure out a reason to actually calculate an airport's DA.

How they hangin’ Francis? Lighten up just a bit.

If’n ya really wanna know consider DA and service ceiling. Yes, folks run into the problem. Big Bear produces a vid every couple of years where somebody can’t get out of ground effect. People run into the problem at Leadville and have to fly down valley rather than climb over a ridge. Maybe you’ve already mentioned being outside the performance charts. Lots of older POHs stop long before Colorado summertime challenges.

Anyway, calculate it or do not. We read about the ones who do not.

 

[BigBadLou]

Math? MATH?!?!?
WITCHCRAFT!!

That's why most pilots don't use TAS, CAS, IAS or any other ASs.
They're afraid.
Or dumb.
Or both.

People are dumb. Get used to it. I ain't gettin' any better. Sorry.

 

[asicer]

What do you do with DA once you know what it is?

Write it down somewhere so that it can say on the NTSB report that I had it.

 

[Pilawt]

Turbocharged or not, as I said earlier, I've never used DA for performance planning. I'm trying to figure out a reason to actually calculate an airport's DA.

There was that warm July day that I was preparing to depart Cortez, Colorado (elev. 5,916’) in a rented Turbo Arrow with my wife and kids. The runway was closed for resurfacing, but we were welcome to use the shorter parallel taxiway ... which aimed right at the fuel island. You dang right I calculated DA ... to the inch.

 

[MauleSkinner]

There was that warm July day that I was preparing to depart Cortez, Colorado (elev. 5,916’) in a rented Turbo Arrow with my wife and kids. The runway was closed for resurfacing, but we were welcome to use the shorter parallel taxiway ... which aimed right at the fuel island. You dang right I calculated DA ... to the inch.

Ok...and what did you do with it?

 

[MauleSkinner]

Write it down somewhere so that it can say on the NTSB report that I had it.

That's really about all its good for most of the time.

 

[MauleSkinner]

How they hangin’ Francis? Lighten up just a bit.

If’n ya really wanna know consider DA and service ceiling. Yes, folks run into the problem. Big Bear produces a vid every couple of years where somebody can’t get out of ground effect. People run into the problem at Leadville and have to fly down valley rather than climb over a ridge. Maybe you’ve already mentioned being outside the performance charts. Lots of older POHs stop long before Colorado summertime challenges.

Anyway, calculate it or do not. We read about the ones who do not.

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?

 

[comanchepilot]

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.

I saw 127 pretty often in my Cherokee 180C at 5500-6500 - I only went higher to escape the bumps or get a tailwind. I'd flightplan 125 but then the hershey bars were more reliable if not a little slower. but they weighted less - so - who knows - you calc'd and live with what you get.

My PA24 is reliably planned at 157 . . .

 

[LongRoadBob]

What, you mean this? At cruise speed, it's neglible, and there really aren't any "calculations" from IAS => CAS. Then add 2% to IAS for every 1000' shown on your altimeter.

View attachment 59768

That was what I was saying, that the conversion is just a table, the conversion to TAS you have a rule of thumb which can be used, but we are taught to calculate it. I'm sure I'll come around to the rule of thumb you mention after gaining experience to know when it is "good enough" or if I might want to actually calculate it.

 

[asicer]

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?

Well if you really want to dig, it does give me an inkling of what to expect. If the DA is soaring and it only takes an inch to lean for best power, I know something is wrong. If I'm only getting a few hundred FPM, knowing it's not because of DA means I have to start troubleshooting.

 

[Kritchlow]

What do you do with DA once you know what it is?

Not for the Piper aircraft, but for the Cessna we used to figure DA then go into the Cessna charts at standard conditions (using DA).
IMO it just made it simpler than doing the chart figuring. YMMV.

 

[Lachlan]

What do you do with DA once you know what it is?

Plea bargain.