Ground speed using E6B

Reply Subscribe

Page 1 of 2

Thread Tools

Search this Thread

01-14-2009 | 06:34 PM

SongMan

Thread Starter

Gets Weekends Off

Joined: Mar 2007

Posts: 430

Likes: 0

From: Cessna 150 Left seat

Ground speed using E6B

So if examiner or a CFI asks their student to find a ground speed in flight using E6B(no GPS), how do you find the wind to reference in order to get the GS?

Is winds aloft what you use even in flight to get ground speed? or is there another methoed to get current winds?

Thanks!

01-14-2009 | 06:42 PM

USMCFLYR

Gets Weekends Off

Joined: Mar 2008

Posts: 13,843

Likes: 1

From: FAA 'Flight Check'

Quote:

Originally Posted by SongMan

You could use 'CTR Flight Following' to tell you your ground speed - but I digress

I thought you figured groundspeed back in the day by timing between two known points on your x/c for example. This thread will probably prodcue a plethra of good techniques!

USMCFLYR

01-14-2009 | 07:29 PM

rickair7777

Prime Minister/Moderator

Joined: Jan 2006

Posts: 44,863

Likes: 658

From: Engines Turn or People Swim

Quote:

Originally Posted by SongMan

If you have a an FMS/GPS, one of your screens will tell actual winds aloft.

In order to calculate GS in advance for flight planning, use the winds aloft forecast.

If you need to get a GS in flight, set a fixed TAS then use a timer between two nav waypoints (VORs). Plug distance and time into the E6B.

Or ask ATC...their radar shows your GS.

01-14-2009 | 09:38 PM

normajean21

Gets Weekends Off

Joined: Sep 2008

Posts: 215

Likes: 0

aww what about point to point and using time the old fashioned way =/

01-14-2009 | 11:45 PM

schwanm

New Hire

Joined: Jan 2009

Posts: 6

Likes: 0

Time taken to cover a distance.. pop time over distance on the E6B and read the GS off that

01-15-2009 | 05:48 AM

NoyGonnaDoIt

Gets Weekends Off

Joined: Nov 2008

Posts: 826

Likes: 0

As others have said, ground speed =in flight= is simple 9th grade algebra. Distance ÷ time = rate (your car speed is calculated in "miles-per-hour", right?. That's just distance/time)

The E6B front side wheel is a ratio calculator. It talks in of "this" ÷ "that". So take the distance ÷ time and put it right on the E6B: distance over time and the pointer will give you your ground speed.

You use the wind side of the E6B to calculate =expected= ground speed based on =forecast= winds aloft.

02-09-2009 | 06:34 PM

A320fan

Line Holder

Joined: Apr 2008

Posts: 64

Likes: 0

From: C172 Right

I was always told to look under the 36 instead of the 60 (rate) when I was finding ground speed in flight. i guess whatever your CFI taught you and whatever method you feel comfortable with.

02-09-2009 | 07:11 PM

jeforte

Banned

Joined: Dec 2007

Posts: 95

Likes: 0

From: PIC

figure your distance traveled in one minute and multiply that by 60

02-09-2009 | 08:13 PM

HSLD

APC co-founder

Joined: Feb 2005

Posts: 5,853

Likes: 0

From: B777

Quote:

Originally Posted by SongMan

Hopefully you've got it from the previous posts that the wind side of the E6B is for flight planning using forecast winds to determine drift angle.

In flight, fly a known distance and time how long it takes to cover that distance. In the cockpit, you'll have to be able to fly a steady course, recognize two points on the ground, and measure the distance between the two points on a sectional.

Check this out if your a more visual learner

YouTube - Learning The E6-B: Calculating Ground Speed - Aviation Video

Timing one minute makes for easy base-6 math but remember that the longer you time the more accurate your calculation.

02-10-2009 | 02:48 AM

#10

Cubdriver

Moderator

Joined: May 2006

Posts: 6,056

Likes: 0

From: ATP, CFI etc.

On a standard sectional one thumb knuckle length is about 10 miles. You can compare your own thumb knuckle to ten nautical miles against the radius of any VOR rose on a standard sectional, because they all have a 10 nm radius. So, using your thumb knuckle to measure the distance between a couple of points you pass on the map and on the ground, note the time it takes to cross those points, then put the ratio into the rotary side of the E6B. Where the 60 is on the bottom dial is your ground speed in knots.