Groundspeed or TAS?

Casper said:
TAS...especially if there is a chart in the AFM/POH. They do not take into account your GS.
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I believe most POH's always use KIAS for the "time, fuel and distance to climb".
But at some point on your VFR nav log you need to account for the wind during the climb if you want to have an accurate checkpoint on the ground.
 
SierraPilot123 said:
I believe most POH's always use KIAS for the "time, fuel and distance to climb".
But at some point on your VFR nav log you need to account for the wind during the climb if you want to have an accurate checkpoint on the ground.
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You will probably not get an accurate checkpoint on the ground no matter what you do. The charts for light planes almost always have you climbing at Vy all the way to cruise altitude, which no one ever does. So why use the chart at all?
 
meritflyer said:
When determining yout top of climb for flight planning purporses, would you want to use the TAS or GS?
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I always taught my smarter students to WAG the TOC using GS - ie get the time for the TOC, throw in an average climb wind component using your E6B to get a groundspeed (and heading), and voila you have a corrected distance. It was actually really accurate. While it may be a good exercise in xcty planning, it just wasn't practical at all or for the ones that had difficulty with xcty planning to begin with. Keep in mind this was climbing to 12,000 feet so the changes actually made a difference. Computing your climb this way for a 2000'-4000' climb probably isn't practical.

Honestly, IMO, all that really matters in xcty planning (outside of the checkride environment) is how much fuel you have on board and picking checkpoints that are easy to see/use. One big thing that I always harped on was converting your fuel on board from gallons to time (hours:minutes format). Converting it to the hour/minute format you could be flying along and just subtract the amount of time you flew to each checkpoint with your total fuel on board and you'd have your fuel remaining. It worked nicely.
 
wheelsup said:
Honestly, IMO, all that really matters in xcty planning (outside of the checkride environment) is how much fuel you have on board and picking checkpoints that are easy to see/use.
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Amen! That was my first thought when I started reading this thread.

A lot of people get so caught up in figuring things down to the second that they forget how many variables can throw the times off. Heck, in a 152, if you start your timer at the start of the takeoff roll, compared to once airborn and on course, you might have a difference of 2 minutes in your time from that alone.

What's the saying about this?...something like...measure with a ruler, mark with chalk, then chop with an axe? No matter how precisely you figure it in theory, it always turns in to a messy approximation in the end.
 
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