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

[Piperboy]

When I flew Beech 1900's back in the 90's at a commuter airline, a passenger asked my copilot "how fast does it fly?" He answered about 210 (knots). In reality this airplane would cruise at more than 260 knots TAS. It would indicate 210.

 

[GlennAB1]

And all the V speeds are based on what?

 

[LongRoadBob]

And all the V speeds are based on what?

Gross weight?

Also the formula for CL.

Testing, demonstrating. Isn't it different depending on the parameter?

But I think if the DA is off the chart, or rather the PA, one can still figure out using CL? Am I way off?

 

[bflynn]

"I don't fly by dead reckoning..."

Nobody in aviation flies DR because we are always flying with reference to a fix. You would be only be DR as you describe it if you turned off all external reference equipment like GPS and VORs, then took off and flew without looking out the window, ie, you would be mostly lost. Even sailors of old didn't use DR exclusively, they sailed from sextant fix to sextant fix. You may not know, but in addition to yacht sailing as a teen, I was also a submarine sailor. We used DR when submerged, but still used other means to verify where we were. So even blind and underwater, we did not rely just on DR...because it could be wildly inaccurate.

You are right, DR is pretty useless to me because I have five better ways to navigate. If I have to fall back on the sixth it is because I am in the clouds without VORs or GPS, my radios are out and my iPad is dead. At that point, like any DR, you take your best guess, look for some place that is most likely safe to break out and go.

I otherwise yield to your superior aviation skills. You are absolutely the better pilot. Enjoy.

 

[Checkout_my_Six]

only folks from the south know how to......recon.

 

[FastEddieB]

And all the V speeds are based on what?

IAS, since about 1976, I think.

Before that it was CAS.

 

[coloradobluesky]

TAS has lots of uses. One is to determine the wind speed and direction. Turn into the wind until you are going the slowest. Need to know TAS for flight planning so you can decide whether to climb high for higher TAS (you have the wind forecasts). Lots of other uses actually. Besides, IAS is slower than TAS. You do want a fast airplane don't you?

 

[luvflyin]

Nobody in aviation flies DR because we are always flying with reference to a fix. You would be only be DR as you describe it if you turned off all external reference equipment like GPS and VORs, then took off and flew without looking out the window, ie, you would be mostly lost. Even sailors of old didn't use DR exclusively, they sailed from sextant fix to sextant fix. You may not know, but in addition to yacht sailing as a teen, I was also a submarine sailor. We used DR when submerged, but still used other means to verify where we were. So even blind and underwater, we did not rely just on DR...because it could be wildly inaccurate.

You are right, DR is pretty useless to me because I have five better ways to navigate. If I have to fall back on the sixth it is because I am in the clouds without VORs or GPS, my radios are out and my iPad is dead. At that point, like any DR, you take your best guess, look for some place that is most likely safe to break out and go.

I otherwise yield to your superior aviation skills. You are absolutely the better pilot. Enjoy.

What about 'pilotage?' Isn't that what the periscope is for?

 

[Velocity173]

TAS has lots of uses. One is to determine the wind speed and direction. Turn into the wind until you are going the slowest. Need to know TAS for flight planning so you can decide whether to climb high for higher TAS (you have the wind forecasts). Lots of other uses actually. Besides, IAS is slower than TAS. You do want a fast airplane don't you?

Exactly. Of course most cases, TAS is greater than IAS. Couple weeks back I was indicating 128 kts at 2,500 ft and an OAT of -15 C. G500 was showing about 125 TAS. Flew the opposite route at 5,500 ft, -11 C, indicating 126 but with a TAS of around 131 and burning less fuel at that.

Some would say TAS isn’t important in planning but 6 kts and saving a few gals an hour at altitude is significant to me. Especially for a long trip.

 

[bflynn]

What about 'pilotage?' Isn't that what the periscope is for?

Periscope actually only went up (on my boat) about once a day and then only for about 5-10 seconds. We spent 99.99% of our time deep, invisible and silent. And blind, which is why we did all kinds of things to figure out how to track our position. The least successful was DR.

Pilotage is flying from waypoint to waypoint using DR in between. But if your waypoints are close enough, you never have to DR.

 

[Checkout_my_Six]

Pilotage is flying from waypoint to waypoint using DR in between. But if your waypoints are close enough, you never have to DR.

so....if ya never go anywheres....DR is easy peasy.

 

[FastEddieB]

Maybe it’s only of passing historical interest, but in the 1980’s I was hired a few times to fly cropdusters to S America. Kinda risky, but followed the island chain down. Pre-GPS, so I either had no navigation radios or at best a jury-rigged VOR, which did not help much at low altitude.

That VOR, a Narco, can be seen duct-taped below the panel on the left:

It may not look far on the map, but several legs had land recede behind me and then an hour or more with no land in sight. It really felt like I was in the middle of the ocean. In these cases DR with just a compass was critically important, and thankfully landfall was usually within a mile or so of projected.

But truth be told, it’s a skill that needs to be practiced, and I’m sure I’d be very rusty at it now.

 

[MauleSkinner]

Maybe it’s only of passing historical interest, but in the 1980’s I was hired a few times to fly cropdusters to S America. Kinda risky, but followed the island chain down. Pre-GPS, so I either had no navigation radios or at best a jury-rigged VOR, which did not help much at low altitude.

That VOR, a Narco, can be seen duct-taped below the panel on the left:

I may not look far on the map, but several legs had land recede behind me and then an hour or more with no land in sight. It really felt like I was in the middle of the ocean. In these cases DR with just a compass was critically important, and thankfully landfall was usually within a mile or so of projected.

But truth be told, it’s a skill that needs to be practiced, and I’m sure I’d be very rusty at it now.

My first trip across the desert at 600AGL with no nav radios taught me how well DR actually works...2 miles abeam my destination 150 miles away.

 

[luvflyin]

Periscope actually only went up (on my boat) about once a day and then only for about 5-10 seconds. We spent 99.99% of our time deep, invisible and silent. And blind, which is why we did all kinds of things to figure out how to track our position. The least successful was DR.

Pilotage is flying from waypoint to waypoint using DR in between. But if your waypoints are close enough, you never have to DR.

I was just kidding about the pilotage with a periscope thing. They was using some pretty serious DR in Red October though, lol

 

[FastEddieB]

My first trip across the desert at 600AGL with no nav radios taught me how well DR actually works...2 miles abeam my destination 150 miles away.

If I'm remembering my math/geometry correctly, the rule of thumb was 1º off equaled 1 mile off over 60 miles. Is that correct?

If so, made it hard for me to miss a large island, even if I was 10º off over 100 miles or so.

If I did miss, I had 150 gals in the hopper and 50 more in the wings. At 15 gph I could fly a long, long time.

 

[luvflyin]

Maybe it’s only of passing historical interest, but in the 1980’s I was hired a few times to fly cropdusters to S America. Kinda risky, but followed the island chain down. Pre-GPS, so I either had no navigation radios or at best a jury-rigged VOR, which did not help much at low altitude.

That VOR, a Narco, can be seen duct-taped below the panel on the left:

I may not look far on the map, but several legs had land recede behind me and then an hour or more with no land in sight. It really felt like I was in the middle of the ocean. In these cases DR with just a compass was critically important, and thankfully landfall was usually within a mile or so of projected.

But truth be told, it’s a skill that needs to be practiced, and I’m sure I’d be very rusty at it now.

An ADF might have been more valuable than a VOR but I suppose it would have been harder to get one of those 'jury rigged' in

 

[Timbeck2]

only folks from the south know how to......recon.

That's "reckon" city slicker.

Also accepted would be reckin, rekin, or recken.

 

[Cooter]

If I'm remembering my math/geometry correctly, the rule of thumb was 1º off equaled 1 mile off over 60 miles. Is that correct?

Close enough for govt work. 360°= 376nm
And evidently close enough for what you were doing. I never had to trust it quite like you did though.

 

[MauleSkinner]

If I'm remembering my math/geometry correctly, the rule of thumb was 1º off equaled 1 mile off over 60 miles. Is that correct?

If so, made it hard for me to miss a large island, even if I was 10º off over 100 miles or so.

If I did miss, I had 150 gals in the hopper and 50 more in the wings. At 15 gph I could fly a long, long time.

Your math is correct. I was a little more worried with only 30 minutes' reserve at 150 miles.

 

[luvflyin]

If I'm remembering my math/geometry correctly, the rule of thumb was 1º off equaled 1 mile off over 60 miles. Is that correct?

If so, made it hard for me to miss a large island, even if I was 10º off over 100 miles or so.

If I did miss, I had 150 gals in the hopper and 50 more in the wings. At 15 gph I could fly a long, long time.

The hopper, of course, that's where you could put some gas. "Dude, see that lever there that says 'spray,' don't touch it." Back around 1980 there was Piper Pawnee that took off out of Santa Barbara being delivered to New Zealand. First leg was to Hilo. My guess is they had a Loran. That would have been some serious Dead Reckoning. It didn't make it by the way. Ran out of gas 50 miles short of Hilo.

 

[FastEddieB]

Thanks for the chance to reminisce.

Related to another thread on fuel valves, on one leg my aux fuel selector started dripping fuel. I found if I exerted upward pressure on it the leaking stopped. My long term solution: