Technical Question for Fellow CFIs...

[GEUAviator]

When planning a climbout to altitude for cross countrys the student and myself will typically use the "Time, Fuel, & Distance to Climb" chart located in the POH.

Now, every chart I've come across only says to increase time, fuel, and distance by ~10% for every 10 degrees above standard. No big whoop...

But, these charts never say anything about effects of wind. The "Time, Fuel, & Distance" charts give data based on no wind.

What's the best way to make more accurate calculations? How would you explain this to a student pilot?

I'm aware of using Pythagoras' Theorem and using vector analysis to find the correct distance and groundspeed , but I'd like to find a better way of coming up with more accurate numbers.

Example: Climb from 1,000 ft. to 6,000 ft. we're climbing at 70 KIAS. Normally I'd just get add/subtract winds to get a groundspeed. How should I do this for the climbout?

Thanks in advance for any responses! I'm just trying to be the best CFI I can be!

GEUAviator

 

[sauce]

Keep it SIMPLE with GA aircraft fuel requirements. I know there are many opinions on this subject but if you look at accident reports where fuel is an issue the owner - pilot didn't even know the BASICS about fuel managment.

My take on fuel (for general aviation aircraft) is that if you have to figure every ounce of fuel and minute of flight, then you don't have enough! That being said, I am NOT a avocate of TANKERING fuel.

I have seen many well meaning CFI's stress a student pilot out by having them do all these complex equations, half the time they will not remember half of the stuff you are telling them, teach the stuff that will keep them out of trouble, I see this being missed at a lot of bigger schools.

Fly smart and the safe part will take care of itself!

 

[midlifeflyer]

sauce said:
Keep it SIMPLE with GA aircraft fuel requirements. I know there are many opinions on this subject but if you look at accident reports where fuel is an issue the owner - pilot didn't even know the BASICS about fuel management.

Amen brother!

GEUAviator,

Think about it. You're talking about trying to figure out a formula so that you can be more precise to the second when calculation time on "forecast" winds.

There is a way. You can probably find the formula on Ed William's page: http://williams.best.vwh.net/


When I did my private, my CFI told me to take the cruise calculation and add 1 minute per 1,000' for the climb. When I started working on a spreadsheet to do my flight planning calculations, I did everything else using complex formulas but, kept the minute/1000 rule of thumb.

It works.

 

[tarp]

Holy Christmas, Batman.

You're measuring with a micrometer and cutting with a chain saw!

What's the student going to do on his 3rd X-C after he gets his PPL? The same as everybody else - either he's gonna do it the hard way and "gut" out a number from the weather and the charts or he's gonna let DUATS do the number crunching for him.

 

[SIGman]

SIMPLE

Wind has no effect on climb performance as it relates to time or fuel burned right?? But it does change distance.

Use climb charts for Time fuel distance.

For distance-
Using time, distance (given in TFD to climb chart) and an E6B you can get the KTAS for the climb.

Ex from 172SP from S.L. to 5000ft

8 min and 10 nm.

Using e6b, I get about 75 KTAS. Now adjust for Hwind/Twind comp.

Lets say I have a 10 average Twind component on climb. 85knots GS, right. Simply move the Arrow (that points to speed) to 85 and get the new distance.

At 85kts GS, I will travel 14 nm in 10 min.

hope it helps.

Cheers,
D

 

[flywithastick]

But, these charts never say anything about effects of wind. The "Time, Fuel, & Distance" charts give data based on no wind.

First of all, remember, wind makes no difference with time and fuel *to altitude*.

There's a lot to be said for rules of thumb. You;ve got some good ones above. But after talking about detailed planning, I tell my people to always look at the big picture. Can you use one of these rules of thumb? does the trip really warrant 2 decimal point accuracy? Is is a night IFR trip over swamps and water? day VFR over pastures and interstates? IMO, it all helps to determine what level of planning you need to use. If you're teaching for a written, get out a Gleim or ASA, and see what they say.

You asked about "accurate" time, fuel & dist to climb estimates - here's what I teach. I'm sure there are variations and maybe even more accurate estimation methods, which I'd like to hear about. But it's all basically still estimation.

Example: Climb from 1,000 ft. to 6,000 ft. we're climbing at 70 KIAS. Normally I'd just get add/subtract winds to get a groundspeed. How should I do this for the climbout?

Assuming we're talking about light GA planes, for the climb distance determination you'll need to know your groundspeed through the climb. what are the winds aloft? I'm guessing this is what you're really asking about.

I teach folks to interpolate the FD info if located between observation points. Locate a couple nearby (on one the same side of fronts!) & interpolate for the altitudes you're interested in using.

To determine distance covered in the climb, you'll probably have to break the climb into a couple of segments, depending on the wind info you have available. lets say you have info for sfc, 3000' & 6000'. Say sfc is 500'. make your first climb segment 1000' to 1800'. Second, 1800' to 4500'. Third, 4500' to 6000'. Use the sfc winds for the 1st segment, 3000' FD for the 2nd & 6000' FD for the 3rd.

Like Tarp said, this is measuring with a micrometer. But worthwhile when teaching the concept. Makes almost no diff when winds are light. Could be an issue otherwise.

Might want to sketch the climb profile and wind vectors/info out on paper or board. Graphics help explain, IMO.

Once you know the GS for these individual segments, and knowing the time to climb through them, you can then estimate the distance covered during the climb.

I point out the accumulation of error that can lead to a false sense of security in these estimates. Think about how accurate is the FD report? Are the climb performance numbers realistic for this plane? Is the pilot good enough to fly the recommended numbers? Just explain all this stuff when teaching these things so they'll know the limitations.

First of all, the question was about accurate methods. There's a lot to be said for good rules of thumb. I personally use AOPA's planner for my trips. This drawn out stuff is a pain in the a$$ and most likely wayl over the overall level of accuracy of the plan, but the question was about teaching acurate time, fuel dist to climb estimates. anyone with a better answer to the question, please jump right in.

 

[chrisdahut24]

I just ignore the distance shown on the table. After I obtain groundspeed, I take that along with time to climb, and plug it into a time, speed distance equation (D = S x T). Just remember to keep the units consistent and convert time into hours first: every so often I'll check a students planning and we have to fly 329 miles to hit 2000 ft! And no, the student didn't think it was strange either!

 

[Riddle momma]

My way

Here's my way of teaching:

Use the time and fuel since these are not related to wind at all.

To find the distance, turn it into a time-speed-distance problem on the E6B:
Climb speed = Climb distance/Climb time

If there is no wind, then they can use the chart distance.

And, just like cars, the published numbers degrade with age. For their safety and my peace of mind, I tell them to add 10% to their estimated fuel burn to compensate for the plane's age.

 

[JediNein]

Howdy!
Our FSDO showed their new fuel awareness video at last weeks WINGS Seminar. There are a few good tips in there. One that caught my attention:

Pilots are very likely to overfly their planned fuel stop if the fuel stop is within an hour of the destination.

Plan the fuel stop more than 1.5 hours from the destination.

The reasoning makes sense, carry an hour reserve, the destination is only XX minutes away and we should have that much fuel on board. The result is a landing within a few minutes of the runway.

Fly SAFE!
Jedi Nein

 

[350DRIVER]

I do not agree completely with this "keep it simple" attitude especially when the issue at hand is fuel management . Kind of a serious issue that needs to be addressed in depth by every CFI. I agree with most points but in no way, shape, or form will I use any "short cut" when teaching my students the importance of calculating fuel burn whether it be on the climb, cruise, or the decent phase of the flight. The graphs are in the POH for a reason, winds aloft are also continuously updated for a reason. I want each and every one of my students to be as exact as possible even if it means spending a substantial amount of time on the ground doing "flight planning".

Obviously if you have a very strong headwind that was unexpected or not anticipated then time to destination will be longer giving you more fuel burn due to longer duration of flight.
I trust the fuel gauges at 2 points- 1) when tanks are empty and 2) when tanks are full. That being said, if weight and balance is NOT an issue then why not top off all tanks and play it safe even though you may not need that much fuel to get to your destination.?? I will top off whenever W&B is not an issue even if it is a short hop due to the fact that things happen and I would much rather have excess than being up there wishing I had more fuel. I try to always expect the unexpected and plan for worse case scenarios with regards to fuel consumption.

Common sense goes a long way sometimes especially when fuel management is the topic.

3 5 0