Calculating TOC and rate of climb

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RomeoSierra

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Romeo Sierra
Hi,

I am still training and learning how to complete nav logs and having some trouble calculating the top of climb from the limited rate of climb info in the POH.

The POH is very limited in the information it gives since all it gives is the following:

Altitude / Vy speed / Rate of climb fpm
0ft / 62 / 825
1000ft / 62 / 783
3000ft / 62 / 685
5000ft / 62 / 576
and so on...
(sorry about the formatting, couldn't upload a picture of it)

I'm trying to calculate the TOC from an airport at ~600ft up to 3,500ft.

First of all, I've always been taught we climb at 70kts not 62kts but even assuming I climb at 62kts how do I work out the fpm rate?

Would I take the initial climb rate of about half way between 0 and 1000ft, say 800fpm and then what it would be at about 3,500ft, say 670fpm and average the two to get ~735fpm and use that for the entire climb?

Then since climbing 2,900 ft at 735fpm makes a time of about 3m56s (round up to 4 mins) work out the distance travelled is 9.15nm (distance = speed of 62kt x time of 0.15hrs).

Or is there another simpler way of doing this that I'm way over complicating?
 
Sounds like you’ve got it. I would have guessed 700 fpm as typical climb (what do you actually see in the aircraft vs some ‘precise’ book number) and used that. Book numbers are great for FAA tests, CFIs, and transport category aircraft. The rest of us just use what we know the aircraft actually does and I haven’t calculated TOC since pp training days. I’m usually stuck underneath a Bravo shelf anyway...
 
And I suppose a follow up question based on this should be how do factor the wind? I've often seen winds at surface at say 200 at 10kts but at 3,000ft they are 250 at 30kts. Should I just pick somewhere in the middle again for the entire climb to plot the route and course? So say 225 at 20kts for the entire climb?
 
RomeoSierra said:
And I suppose a follow up question based on this should be how do factor the wind? I've often seen winds at surface at say 200 at 10kts but at 3,000ft they are 250 at 30kts. Should I just pick somewhere in the middle again for the entire climb to plot the route and course? So say 225 at 20kts for the entire climb?
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The wind direction and speed change is a low agl phenomena for the most part. I’d just use the number at altitude. Dunno what ‘official’ guidance is on that one.
 
It is simpler, much simpler, but not necessarily during training. During training, part of the goal is for you to learn how to do it the long way and compute to a high degree of certainty a number which is no more than an estimate.

That's something I've told my students - we need to compute many things to the minute or foot or mile which are only ballpark estimates based on guessed inputs.

Just do it and learn it. You might ask your CFI if there are acceptable shortcuts. I actually never computed TOC or used the ROC climb table until I was a CFI. Not even as a student pilot. My CFI said to just add 1 minute per 1,000' to my first leg calculation and my DPE was okay with that. Some years later, whole creating a navigation spreadsheet (before such things were easily available online) I compared that to "long division" and the results were pretty close to each other.
 
RomeoSierra said:
And I suppose a follow up question based on this should be how do factor the wind? I've often seen winds at surface at say 200 at 10kts but at 3,000ft they are 250 at 30kts. Should I just pick somewhere in the middle again for the entire climb to plot the route and course? So say 225 at 20kts for the entire climb?
Click to expand...
We pretty much disregard variable winds during the climb. Just another example of why it's only a ballpark estimate.
 
As said above, just plan for the winds that are forecasted at your cruising altitude. Keep in mind that these are only forecasted winds so the WCA may need to be adjusted once you get out and see what effect they’re really having on the airplane.
 
Sounds like I am overthinking it then. When I asked my CFI last time his response was just "yeah sure, looks good" and didn't seem too worried it wasn't precise.

During my last XC as well I had planned on staying under the bravo all the way out as well but then ATC cleared me directly into it so that shot up my nav log anyway
 
Remember that you are dealing with really fuzzy numbers...forecasts, estimates, manufacturer;s expectations....and don't expect accuracy. After takeoff everything will change. It has been decades since I had a primary student, but I don' remember ever requiring a TOC calculation. I do not include a discussion of the subject in
 
Ooops. ...of the subject in THE COMPLETE PRIVATE PILOT.

Bob
 
The DPE who does a lot of check rides in my area requires TOC & TOD so all of the instructors at my school teach it.
 
If I can introduce a modicum of practicality here....

TOC calculations are not discussed in the Airplane Flying Handbook or the Pilot's Handbook of Aeronautical Knowledge. TOC is not mentioned in the Certification Standard that the examiner uses on your checkride. It is not worth burning up brain cells when there are far more important things to learn and understand.

Let's say that you plan a flight as accurately as possible using FORECAST winds from the FB, which requires interpolation and is almost always wrong. Chances of your ability to maintain a calculated rate of climb to cruise altitude are nil. You use manufacturer's performance data derived by an experienced factory test pilot/engineer flying a brand-new airplane behind a brand-new engine. Your calculated ESTIMATE for time of arrival is 90 minutes. Do you think that someone from the FAA will be waiting at your destination with a stopwatch?

Heck, an airliner that arrives within 15 minutes of its ETA is considered to be ON TIME.

Don't sweat the small stuff.

Bob
 
RomeoSierra said:
First of all, I've always been taught we climb at 70kts not 62kts
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Unfortunately, manufacturers typically only provide the data for "best rate of climb", while at the same time suggesting you perform a "cruise climb" for improved engine cooling and better visibility. From personal experience, a cruise climb will have approximately the following effects versus a Vy climb in a garden variety trainer: a 20% reduced climb rate, taking 25% more time and covering 40% more distance. The only way to be sure would be to collect your own data for the airplane you fly.

RomeoSierra said:
Would I take the initial climb rate of about half way between 0 and 1000ft, say 800fpm and then what it would be at about 3,500ft, say 670fpm and average the two to get ~735fpm and use that for the entire climb?
Click to expand...

Yes.

RomeoSierra said:
Then since climbing 2,900 ft at 735fpm makes a time of about 3m56s (round up to 4 mins) work out the distance travelled is 9.15nm (distance = speed of 62kt x time of 0.15hrs).
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Does your POH not have a "Time, Fuel, and Distance To Climb" table? If it does, you should be using that, instead of (or in addition to) the rate of climb table. Such a table saves some of the math above. Note that either way, the distance calculated is for a no-wind condition. The time and the fuel will be the same regardless of wind, but distance will not.

To determine distance while accounting for wind, determine the average indicated climb speed. Convert from indicated to true airspeed. Account for the average headwind to get groundspeed. Then calculate the distance flown in the amount of time it takes for the climb.

RomeoSierra said:
Or is there another simpler way of doing this that I'm way over complicating?
Click to expand...

Like others, I never calculated a TOC as a student and when your cruise altitude is only 2,000' AGL or so it doesn't make much difference. You could attempt to calculate it precisely, but the more careful and precise you try to be, the less it really matters. In other words you could spend double the amount of effort on this problem for maybe a 2% increase in accuracy.

Often, with consideration of the performance chart, wind, and familiarity with the airplane, an educated guess at the TOC can get you close without much effort.
 
The magic screen in the airplane figures all this for you.
 
Thanks @bobmrg, I'll not sweat it anymore then. At the end of the day ATC will probably just tell me when to climb and descend anyway which will just wipe out any calculations I have done anyway. Guessing this is why my CFI wasn't too bothered about getting anything correct and only gave it a quick glance
 
RomeoSierra said:
Sounds like I am overthinking it then. When I asked my CFI last time his response was just "yeah sure, looks good" and didn't seem too worried it wasn't precise.

During my last XC as well I had planned on staying under the bravo all the way out as well but then ATC cleared me directly into it so that shot up my nav log anyway
Click to expand...

Technically you weren't "over" thinking it, you thought about it quite a bit and learned that it's nearly impossible to get it 100% accurate. :) Which... is kinda the whole point of the exercise.

NHWannabe said:
The DPE who does a lot of check rides in my area requires TOC & TOD so all of the instructors at my school teach it.
Click to expand...

An example of teaching to the examiner instead of to the standard. ARGH! But they're at least looking out for y'all.

Where understanding TOC really starts to come in handy is Instrument departures, and minimum feet-per-nautical-mile climb requirements. Then it can mean a lovely flight, or a crunch just a few feet from the top of the mountain in IMC. :) No bueno.

TOD you figure out why you should have SOME sort of plan, the first time you really make some friends and early passengers uncomfortable and their ears pop, when you realize to get down from HERE to THERE (points down at airport) you have to do a slam-dunk arrival. :) :) :)
 
RomeoSierra said:
Thanks @bobmrg, I'll not sweat it anymore then. At the end of the day ATC will probably just tell me when to climb and descend anyway which will just wipe out any calculations I have done anyway. Guessing this is why my CFI wasn't too bothered about getting anything correct and only gave it a quick glance
Click to expand...
Romeo, I assume you've done this, but take a few sample written tests and see what the questions are like. It's been a long time since my private written so I forget the questions there, but I just took the IR written and it ticked me off on how sometimes close enough was good enough and other times things were required to be very precise. There was no rhyme nor reason in my mind. But the prep questions helped realize that so I was pretty precise with everything. For what its worth your op is how I would handle a problem like that.
 
PaulS said:
Romeo, I assume you've done this, but take a few sample written tests and see what the questions are like. It's been a long time since my private written so I forget the questions there, but I just took the IR written and it ticked me off on how sometimes close enough was good enough and other times things were required to be very precise. There was no rhyme nor reason in my mind. But the prep questions helped realize that so I was pretty precise with everything. For what its worth your op is how I would handle a problem like that.
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Lots of fuel consumption crap on the commercial test. I guess some of the POH tables may have useful, accurate data. I’m not so sure that I believe it until I have some actual time in the plane along with some fuel receipts.

Anyway, no TOC, TOD numbers in the flight planning questions. Lots of range, duration, and fuel required questions. I guess the FAA has figured out that avoiding fuel exhaustion is a good thing.
 
denverpilot said:
An example of teaching to the examiner instead of to the standard. ARGH! But they're at least looking out for y'all.

Where understanding TOC really starts to come in handy is Instrument departures, and minimum feet-per-nautical-mile climb requirements. Then it can mean a lovely flight, or a crunch just a few feet from the top of the mountain in IMC. :) No bueno.

TOD you figure out why you should have SOME sort of plan, the first time you really make some friends and early passengers uncomfortable and their ears pop, when you realize to get down from HERE to THERE (points down at airport) you have to do a slam-dunk arrival. :) :) :)
Click to expand...

Definitely looking out for us, hasn't skimped on any standards and she has been pretty honest about things that are on the written and things that are important in real life flying.
 
Yeah, as @denverpilot stated, TOD is worth some thought.

Best would be to time the start of your descent so you end up near the altitude where you want to be at the right place/time. An example would be to descend at or near pattern altitude close enough to the airport where you’re not having to spiral down or slip majorly in the airport airspace or driving along at 1000ft AGL for 10 miles until you get in the pattern.

After a while, you’ll be able to do the calc in your head. Last weekend at both my destination and home base, I had to lose a lot of altitude. It’s a fun game to try to get it perfect.
 
I had the same questions when I was a student. My instructor said we’re measuring with a micrometer and then cutting with a chainsaw.
 
455 Bravo Uniform said:
Yeah, as @denverpilot stated, TOD is worth some thought.

Best would be to time the start of your descent so you end up near the altitude where you want to be at the right place/time. An example would be to descend at or near pattern altitude close enough to the airport where you’re not having to spiral down or slip majorly in the airport airspace or driving along at 1000ft AGL for 10 miles until you get in the pattern.

After a while, you’ll be able to do the calc in your head. Last weekend at both my destination and home base, I had to lose a lot of altitude. It’s a fun game to try to get it perfect.
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This is a good example. Descent and climb calculations worth some thought because they apply to things other than departure and arrival. It becomes, not a planning exercise at a table, but something done in flight in real time. In IFR, we get crossing restrictions. Even VFR, we may need to ballpark these to get to a certain altitude at a certain point.

The example which comes to mind is a flight I took with a friend (from Centennial in Denver to Cabela's in Sidney, NE for those familiar). On the way back we were flying high and needed to drop down to get under the DEN Class B shelf. I started down at a comfortable 500 FPM pace and my friend was concerned I wasn't going down faster. But I had ballparked the simple calc and we got to our altitude about 3 miles from the ring,
 
Once again the magic screen will calculate this for you if you have it, the 430 does a nice job..... It's a great time to be aviating. That said, calculating the rate needed beyond the nearest 100 fpm seems rather dumb to me, I guess other than to prove you can do it. Estimating and rounding work well here. 120 knots is 2 miles a minute, if you need to get from 4000 to 2000 @ 500fpm you divide 2000 by 500 which gives you 4 minutes to get down. 2 miles a minute times 4 minutes equal 8 miles out. I would round up to 10, close enough if there are no other restrictions.
 
Foreflight calculates TOC. Also TOD top of descent.

Both the iPad and web versions.

To do it, plan your trip in maps, send it to flights, then click the purple Navlog button.

I assume it takes into account winds. It is necessary to specify the Performance Profile of your aircraft (many are built in already)
 
Its important that you know HOW to do it. Average the high and low figures to get a middle figure. Use that to calculate the time to climb for that segment. Do that for all the segments. Then add those figures up. And, get the RIGHT answer. Review your work and make sure its the right answer. Take your time, don't give up. Sometimes these problems take a lot longer than you think. Take as long as you want. Its just a skill that pilots should have. Basic math.
 
Ryanb said:
Not all of us have that luxury, Paul.
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Yeah, but some insist on pointing out that learning can be bypassed with a gadget. You know, like the McDonalds employee who would be lost if there weren't pictures of the selections on the register.

Even when the thread is started by someone who says
I am still training and learning how
Click to expand...
 
midlifeflyer said:
Yeah, but some insist on pointing out that learning can be bypassed with a gadget. You know, like the McDonalds employee who would be lost if there weren't pictures of the selections on the register.
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On a side note a McD near me put in kiosks. Great, I think... I should be able to fly through that thing faster than waiting on the doofuses at the counter...

Nope. You can’t tell the kiosk you want ONLY the drink upsized in a combo meal. You can customize everything else it would appear, but not the drink size. If you want a large drink you have to tell it you want a large combo. Argh.
 
midlifeflyer said:
Yeah, but some insist on pointing out that learning can be bypassed with a gadget. You know, like the McDonalds employee who would be lost if there weren't pictures of the selections on the register.

Even when the thread is started by someone who says
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Oh lighten up Francis.
 
denverpilot said:
On a side note a McD near me put in kiosks. Great, I think... I should be able to fly through that thing faster than waiting on the doofuses at the counter...

Nope. You can’t tell the kiosk you want ONLY the drink upsized in a combo meal. You can customize everything else it would appear, but not the drink size. If you want a large drink you have to tell it you want a large combo. Argh.
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You can tell it to make it a large coffee with the ... errr, ummm, happy breakfast. MickeyD knows what’s important.
 
NoHeat said:
Foreflight calculates TOC. Also TOD top of descent.

Both the iPad and web versions.

To do it, plan your trip in maps, send it to flights, then click the purple Navlog button.

I assume it takes into account winds. It is necessary to specify the Performance Profile of your aircraft (many are built in already)
Click to expand...

Does FF put the TOC/TOD on the map too then?

The TOC/TOD lat-long output on the navlog isn’t really much help except for maybe knowing how long into the flight to expect it.

I don’t have my iPad with me to check.
 
455 Bravo Uniform said:
Does FF put the TOC/TOD on the map too then?

The TOC/TOD lat-long output on the navlog isn’t really much help except for maybe knowing how long into the flight to expect it.

I don’t have my iPad with me to check.
Click to expand...

No, ForeFlight does not provide a way to mark the TOC or TOD locations automatically on the map. It just gives you time and distance, on the Navlog table.

I've found the TOD to be useful for planning my descent -- while flying I watch the distance remaining to my destination on a GPS, and when it diminishes to the TOD point in my Navlog I then initiate the descent.

By the way, you don't have to have your iPad to check. The ForeFlight Web version is very similar.
 
midlifeflyer said:
Yeah, but some insist on pointing out that learning can be bypassed with a gadget.
Click to expand...

I assume you're directing this complaint to me. Sorry if I ruined the thread for you, by offering information that might be useful for some other reader.
 
NoHeat said:
I've found the TOD to be useful for planning my descent -- while flying I watch the distance remaining to my destination on a GPS, and when it diminishes to the TOD point in my Navlog I then initiate the descent.
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You know theres also “Rate of Descent to Destination” as one of the available data items for the bar across the bottom, right?

Wait until it says a bit less than 500 (unless you’re not going to let the airspeed go up in the descent), like maybe 400, and start down then.

Or whatever rate down you like. :)

And of course keep in mind it’s calculating to the ground, not pattern altitude so you get that back also.

Pretty useful. I have that one on one of the data points and just leave it there. If it gets above 500 I’m late starting down for passenger ear comfort. :)

Since it’s calculated in real time and not a prediction from winds aloft forecasts, it can be dead nuts on if you maintain the same airspeed in the descent.

But you do already have that pattern altitude cushion anyway so if your not flying something that’ll come screaming down, it works well.
 
denverpilot said:
You know theres also “Rate of Descent to Destination” as one of the available data items for the bar across the bottom, right?

Wait until it says a bit less than 500 (unless you’re not going to let the airspeed go up in the descent), like maybe 400, and start down then.

Or whatever rate down you like. :)

And of course keep in mind it’s calculating to the ground, not pattern altitude so you get that back also.
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other EFBs do it a bit differently. IFly, for example, does it to pattern altitude at a user-selectable (between 1 and 10 NM) distance from the airport.
 
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