Estimate of flight time

B

bdoss2006

Pre-Flight
Joined
Mar 1, 2025
Messages
72
Display Name
bdoss2006
what is the best way to make a rough estimate of flight time for a flight in the future? Of course if you are doing a flight in the near future, you calculate the times and speeds based on current wind and conditions. But if it is for example 2 weeks in the future, how is the best way to roughly estimate the time and fuel required etc.?
 
Be conservative. Since the winds are normally from the west if going east plan on no winds and going west plan on a 20 knot headwind.
 
Make something up? Farmers almanac? Absolute crapshoot.

For nav log purposes, just take current weather
 
Two weeks out is a long time considering accurate forecasts aren’t available. Use best available information and refine it along the way.

With GA the real questions are will I be able to fly that day and when will I need gas.
 
bdoss2006 said:
what is the best way to make a rough estimate of flight time for a flight in the future? Of course if you are doing a flight in the near future, you calculate the times and speeds based on current wind and conditions. But if it is for example 2 weeks in the future, how is the best way to roughly estimate the time and fuel required etc.?
Click to expand...
You could plan a few different scenarios — no wind, 10 knot headwind, 20 knot headwind, etc. From there you can only make probabilistic guesses, e.g. if you're going west you're more likely to have a headwind, a tailwind is more likely if going east, etc.
 
It depends on the KTAS of your aircraft, but for longer flights I take the drive time multiplied by .33 for the higher performance singles (SR22, 182RG, 210, M20J) and drive time multiplied by .5 for lower performance stuff like a 172.
 
bdoss2006 said:
what is the best way to make a rough estimate of flight time for a flight in the future? Of course if you are doing a flight in the near future, you calculate the times and speeds based on current wind and conditions. But if it is for example 2 weeks in the future, how is the best way to roughly estimate the time and fuel required etc.?
Click to expand...
I have my foreflight to understate my planes speed by 10kt to account for the fact that every flight I've ever done has had a headwind. If you're a student, just do neutral winds and be prepared to explain how you will use real data closer to the flight. If you're already licensed and planning a trip, be conservative. It's no fun planning something that turns out to be sketchy because of weather and/or lack of alternates for fuel/rest/food.
 
Distance is a dangerous concept in flight planning. You only ever have one max: time (4 hours with full tanks, in my case.) How far will I go? Depends on the winds. But it’s always 4 hr max. Having said that, a long way out from the flight I plan 300 miles max with zero wind. Be conservative. This far out, have 3 flight planning options with say a 200 mile, a 250 mile and 300 legs.

————
Btw, when you plan an alternate, plan it behind you, over ground you’ve already flown over, & where you’ve seen the weather.
 
Last edited:
bdoss2006 said:
what is the best way to make a rough estimate of flight time for a flight in the future?
Click to expand...

The "best" way depends on how "rough" of an estimate is acceptable and why you want to know.

- If you're trying to guess whether you'll need a fuel stop, for example, you'll want a very conservative estimate, so you might assume a 20 knot headwind.
- If you're trying to tell a traveling companion approximately how long a trip will take, you might calculate the time assuming no wind, then put a +20% boundary around it so you can tell them, "Oh, about two and a half hours, give or take thirty minutes."
- If you're trying to decide whether to fly your Ercoupe or your Gulfstream, just assume no wind.
- If you're trying to satisfy a DPE's question, obtain 20 years of historical wind data all along the route, determine the mean and standard deviation, then run Monte Carlo simulations of your proposed flight at each of the altitudes that would be appropriate for the direction of flight.
 
Half Fast said:
- If you're trying to satisfy a DPE's question, obtain 20 years of historical wind data all along the route, determine the mean and standard deviation, then run Monte Carlo simulations of your proposed flight at each of the altitudes that would be appropriate for the direction of flight.
Click to expand...
You had me at monte carlo simulations...
 
Something else to consider. During the summer, how far & long you can go is likely going to be determined by your tolerance for turbulence & how much punishment you can take. Turbulence is quite tiring after a while. I like to start very early but be bedded down by noon, one pm at the latest.
 
Figure it for no winds and for plus minus 10 20 and 30

Once you have the distances it's not hard to divide by x and multiply by 60 for minutes each leg. I did this in training and just used the closest one day of.
 
For what purpose? Need more information to be able to provide a useful answer. Upcoming check ride? To be able to tell your spouse it takes "about 3 hours"? Trying to figure a fuel stop? Seeing if you need to leave a fat friend behind to make it with no stops?

I can't imagine a reason you'd really need to be precise 2 weeks out.
 
Start with foreflight and leave off the current wind.
 
Welp…airplane performance and distances aren’t going to change in the next two weeks, so you can do that math now.

You asked, “…best way to make a rough estimate…” Winds aloft are pretty much estimates anyway, so either do a no-wind calculation or check the winds aloft just before you need them.
 
If you know someone with ForeFlight, it will do a Briefing with Historical Winds. But if the trip is really a week or weeks out, I don't really do any specific planning. Many of our long trips (X-US) we usually plan stops at places we want to go to. So we may only fly one leg in the morning to get somewhere that we want to spend the afternoon and evening at. Then we'll move on the next day to either continue to our final destination or for another overnight.

But if you really need to have the "what ifs" now, just plan two trips... One with zero winds or light headwinds and then figure out your fuel stops. Then plan another trip with major headwinds and plan a flight for those required fuel stops. There's a chance one or the other will be usable when you get close to your Departure Date. But odds are you'll have to recalculate the specific times the night before the flight. So that may mean picking a whole new set of fuel stops based on the current Wx.
 
Clip4 said:
It depends on the KTAS of your aircraft, but for longer flights I take the drive time multiplied by .33 for the higher performance singles (SR22, 182RG, 210, M20J) and drive time multiplied by .5 for lower performance stuff like a 172.
Click to expand...
I’m amazed how frequently my flights are almost exactly a third of drive time.
 
eman1200 said:
You spelled “plan on headwinds both directions, because aviation” wrong :)
Click to expand...
I actually had a trip last fall that was tailwinds BOTH directions. Not much of one westbound, but still 4 knots tailwind component is fine by me.
 
bdoss2006 said:
what is the best way to make a rough estimate of flight time for a flight in the future? Of course if you are doing a flight in the near future, you calculate the times and speeds based on current wind and conditions. But if it is for example 2 weeks in the future, how is the best way to roughly estimate the time and fuel required etc.?
Click to expand...
Do students learn how to mark up paper charts, use rulers, protractors, and an E6b anymore? I don’t know, that’s how I learned. I think it’s becoming more common to just put the flight plan together and press the “calculate” button.

Draw each leg of the flight. Do the math for each leg, add them together, done.

As wind speeds and direction predictions start coming in, adjust the groundspeed calculations for each leg. These winds then change your expected heading. And now you just completed a nav log, too. Repeat as necessary, even during the flight. This isn’t rocket surgery.
 
Matthew said:
Do students learn how to mark up paper charts, use rulers, protractors, and an E6b anymore? I don’t know, that’s how I learned. I think it’s becoming more common to just put the flight plan together and press the “calculate” button.

Draw each leg of the flight. Do the math for each leg, add them together, done.

As wind speeds and direction predictions start coming in, adjust the groundspeed calculations for each leg. These winds then change your expected heading. And now you just completed a nav log, too. Repeat as necessary, even during the flight. This isn’t rocket surgery.
Click to expand...
I carried a CR-5 in my pocket for 35 years…No wind, ground speed and time; forecast winds, ground speed and time; 20 knots extra headwind, ground speed and time.

Takes way more time to type it than to calculate it.
 
MauleSkinner said:
I carried a CR-5 in my pocket for 35 years…No wind, ground speed and time; forecast winds, ground speed and time; 20 knots extra headwind, ground speed and time.

Takes way more time to type it than to calculate it.
Click to expand...
I have one of those, too. My E6b still hangs out in a pocket of my kneeboard. I haven’t touched it in at least a year, though. I think used the wind correction side to remember how it worked. I used to set my estimated GS on the pointer before each flight. It’s pretty simple to eyeball time and distance that way, but GPS is already doing that for you.
 
Half Fast said:
But would you be able to understand and appreciate grocery store butter if you hadn’t first learned to churn your own? And how can you detect bad butter without knowing how to churn it by hand?
;)
Click to expand...

Most importantly, if my EFB and my two backup devices failed, would I be able to navigate using the paper charts that I have not carried for 10 years? I had a protractor but it broke in 2012.

I mean, I still have charts labeled with TCA and ARSA ...
 
Last edited:
Ed Haywood said:
Most importantly, if my EFB and my two backup devices failed, would I be able to navigate using the paper charts that I have not carried for 10 years? I used to have a protractor but it broke in 2012.

I mean, I still have charts labeled with TCA and ARSA ...
Click to expand...
I don’t remember when WACs were discontinued, but I still have a few somewhere. I used to have a good time laying one open on the kitchen table and doing a “what if” xc. I can’t remember how many I planned like that, but I actually flew a couple of them. For long trips it’s hard for me to visualize, or whatever you want to call it, the whole route when I can only see a zoomed in area on my tablet. If I zoom out to see the whole route I lose the details. I think I can find my protractor and scale, maybe.

I never expected to be that guy that says, “Back in MY day!” But the OP asked a simple question that can be handled with a pencil and paper, and some educated guesses on winds.
 
Matthew said:
Do students learn how to mark up paper charts, use rulers, protractors, and an E6b anymore? I don’t know, that’s how I learned. I think it’s becoming more common to just put the flight plan together and press the “calculate” button.
Click to expand...
To some degree yes. Going though those processes can teach the underpinning of what the EFB is doing behind the scenes. I have always liked the wind triangle side of the manual E6B because it helps pilots who learn visually picture how the wind is affecting flight. And there's a good case to be made for spreading a paper sectional (if you can find one these days) on a table to discuss airspace and chart markings as part of the ground for the first dual cross country flight.

But the good instructor is teaching those things without needing to rely on paper, slide rule, and plotter. The reality is that the pilot will almost invariably toss that paper chart when it expires (or use it as cool wrapping paper) so it's far more important to teach the use - and limitations - of the tools the pilot with actually use than stuff they will throw away the day after the realize how unnecessary it is.

I still have my manual E6B and plotter. I even have a parallel plotter - a gimmick that is apparently no longer available, which allowed you to get the magnetic course directly from nearby VORs. But they sit in a binder I created for teaching a long time ago and, except for teaching primary, I haven't used any of them myself since 1992.
 
You must log in or register to reply here.
Back
Top