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Aviator168

Well Known Member
How do you guy do it? If there is no wind, ground speed is equal to TAS. But what if there is a tail wind, do I just sum up the TAS and the wind speed and call it ground speed? I know this is not that accurate, but how much am I off? Thnx.
 
In the old days, they called in Pilotage....

We used charts, waypoints and distances. Simple math on the whiz wheel. Dont they teach this in ground school anymore?
 
JonJay said:
We used charts, waypoints and distances. Simple math on the whiz wheel. Dont they teach this in ground school anymore?
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Oh, that's the way we are supposed to do it! Duh!!!

Either that or call the controller on the radio and ask.
 
Look at the GPS for instantaneous
Ask ATC what they are showing
Use a map, time it, and do the math (like we were taught to)

After flight following, go to www.flightaware.com and put in your tail number. You'll get a minute by minute ground speed if you click on track log. Nice part is you can compare your TAS to ground speed to see what the head/tail wind was for the trip.
 
Not sure I could use a whiz wheel anymore...

N941WR said:
Oh, that's the way we are supposed to do it! Duh!!!
Either that or call the controller on the radio and ask.
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Ha!
I know I have one somewhere. (I do keep it in my flight bag, but it would be a tough reach if my GPS ever went out in the wrong spot.) We are so spoiled.
 
N941WR said:
Oh, that's the way we are supposed to do it! Duh!!!

Either that or call the controller on the radio and ask.
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There are a lot of places GA planes going to have not ATC. Reading charts won't give you the instantaneous ground speed. I guess that's probably the best thing we have without a GPS.
 
I think it is important to turn off the GPS once in a while and do some good old pilotage jsut to remember how.

And what ever you do, don't rely on GPS in the mountains, especially if it does not have a good terrain presentation. Without the terrain they can and have led people to their deaths in what turned out to be the wrong canyon...

Randy C
 
Plan the flight and fly the plan

Plan the flight and fly the plan. If you do this you will know your ground speed at every checkpoint. I do this on every cross country flight but I also monitor the GPS ground speed near real time.

Bob Axsom
 
Randy said:
I think it is important to turn off the GPS once in a while and do some good old pilotage jsut to remember how.

And what ever you do, don't rely on GPS in the mountains, especially if it does not have a good terrain presentation. Without the terrain they can and have led people to their deaths in what turned out to be the wrong canyon...
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I confess....

I love GPS, and most likely will leave it on. I've been using moving map versions since the early ninties when they became available. It's true, that the simple black line versions of the past have contributed to mountain accidents. Of course, these days, GPS with terrain data-bases can be had for cheap. I use a Garmin 696, but have a Lowrance 600 that I picked up for $299 when they were on sale. They are about $499 these days.

As far as using GPS in mountain areas, they do work great. You'd have to be in an awful narrow canyon for it not to work. And if the GPS has a half decent moving map, you'd never end up in that canyon to start with. About five years ago, a Mooney took off from the airport next to my home. Clouds were half way down the mountains; but the pilot, who was un-familiar with the area, figured that he could follow the freeway to clearer skies in the distance. Unfortuantely, he followed the wrong road as the freeway curved, and ended up in a blind canyon. It was fatal. In this case, a moving map GPS would have probably saved his rear. And the same for two other accidents in this area, that had flight instructors on board. Both had GPS's; but of the older black line variety. Both hit mountains by using a direct course, and not checking the minimum altitudes first.

My GPS (696) is great! The terrain map automatically turns on when getting close, and a female voice says "terrain - pull up, pull up"... :)

As far as pilotage goes, I practice that too. Afterall, I live and fly in a very mountainous & rugged area. Flights need some advance preperation when flying around here. IMO, just leave the GPS on. At least I do, because I don't believe in the "old fashioned way"............anyway.

L.Adamson --- RV6A
 
Me too brother!

I get out my sectionals, my low altitude enroute IFR charts and the US LO chart, my flight plan sheets, electronic E6B and plotters and go to work. In recent years my wife has taken an interest in helping with the planning and she fills in the log as I plot and respond to her prompts for input. Then I run the calculator to determine leg and total flight times and the total distance and the distance remaining at each check point and she enters the numbers. In the end we are both involved directly in the planning and are prepared for the trip. As we fly along I enter the takeoff time and the time I expect to reach the next checkpoint. When we actually reach the checkpoint I enter the time and the the time I expect to reach the next checkpoint. At each checkpoint the flight plan provides for entering the actual ground speed which is just a time and distance calculation. Typically I flight plan conservatively for 150 kts ground speed and all I do is make sure the time I enter is earlier than the "expected" arrival time. If headwinds start making it go the other way then I get concerned about the ability to reach the planned destination with a good fuel margin.

Bob Axsom
 
Randy said:
I think it is important to turn off the GPS once in a while and do some good old pilotage jsut to remember how.

And what ever you do, don't rely on GPS in the mountains, especially if it does not have a good terrain presentation. Without the terrain they can and have led people to their deaths in what turned out to be the wrong canyon...

Randy C
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Every year our EAA chapter hosts a "race" AKA Navigational Challenge. The pilots are told what three airports they have to fly over and photograph the night before the event. They have to come prepared with their estimated times and fuel burn. (We weigh the planes before and after each flight to determine fuel burn.) The total flight does not exceed 150 miles to Cubs, camps, etc. can join in as well as the fast glass stuff.

The key is you are only allowed to use pilotage, no nav equipment may be turned on.

The planners always pick airports that are stuck down in a valley or are just simply hard to spot from the air.

It is always fun to watch guys pull out their whiz wheels when they get the winds and do the calc's.

The winner is determined by the lowest combined error between the estimated vs actual time and fuel.

Of course, the bragging rights the winner gets are always used appropriately. :rolleyes:
 
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We taught some rough estimation techniques in USAF pilot training. First to answer your question: Yes add tailwind or subtract headwind to TRUE airspeed to convert to groundspeed.

To find a pretty darn accurate TRUE airspeed take half your altitude and ADD it to your INDICATED airspeed. (We used knots, so I'm not sure how well this works with MPH.) For example if you are going 150 IAS and are at FL100, add 50 knots to your indicated for a total of 200 KIAS. (I know, I know, flight levels start at 18,000 and above, but we tried to keep it simple!)

Another amazingly accurate way to determine GROUNDSPEED without GPS:

1) Fly inbound or outbound along a VOR radial
2) Time the number of TENTHs of a mile you travel in 36 seconds. (If you went one mile that would be ten tenths. . . .two miles 20 tenths, etc.)
3) The number of tenths tell you your approximate groundspeed. (I.e. if you travel 16.5 tenths you are going about 165 KIAS groundspeed.)

We used these methods to fly 200 plus mile low levels using the most basic of VOR/DME equipment and the average student could hit their time on target within 10 seconds! Pretty amazing if you've ever seen a T-37 cockpit!
 
I time myself over section lines, then divide 3600 by the number of seconds it takes to travel 1 mile. The answer is my groundspeed in mph.
 
<<I think it is important to turn off the GPS once in a while and do some good old pilotage jsut to remember how.>>

I'm glad you said that. I have friends who will be in big trouble when their GPS battery dies.

Back in 96 I finished an L-4 restoration and one of the old hands at our airport gave me a present to go with it; a genuine 1943 military issue whiz wheel, brand new in the box. So, just for the fun of it I flew to S&F the following month using only the wet compass, the whiz wheel, my wristwatch, sectionals, and a pencil. Landed at Zepher to dig a handheld out of the bag for the Lake Parker approach, the first time I turned on anything electronic. It was a huge pleasure to do it all the 1943 way, logging minutes, correcting ETA for the next checkpoint and squinting at the tire for wind drift.
 
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