Winds aloft but I'm not that high

[pilotod]

If I'm at 7500 (airport is at 5100) and the lowest available winds is at 9000, what would I use as my wind for calculations?

And if the origin airport is different than the destination airport, how is that factored into the navigation?

Thanks,
Jamie

 

[jaybee]

Interpolate.

Take destination and departure winds and average the speed and direction.

Take winds aloft and winds on the ground and again average the speed and direction.

Close enough for hand grenades, horseshoes and flight planning. Seems counter intuitive to plan fuel that sloppily but that is why we are required to land with minimum fuel reserves. 30 minutes for fixed wing VFR.

Example -

Departure winds 270 at 14
Destination winds 280 at 10

Plan for 275 at 12.

 

[MBDiagMan]

I would be using surface winds. If they are significantly different, check winds at a few locations along the way and make your best judgment. If the wind is in your favor at 9,000, why not climb to that altitude for the trip?

 

[upstateny]

For long cross countries, use the winds along the route.
Example: Departure - 270 @ 4
Enroute - 320 @ 12
Destination - 250 @ 10

or add as many enroute checkpoints as you need where winds are available.

It's more accurate than averaging the departure/destination winds. (In the example, the average would be 260 @ 7. You'd end up a bit off course to the south.)

 

[jaybee]

For long cross countries, use the winds along the route.
Example: Departure - 270 @ 4
Enroute - 320 @ 12
Destination - 250 @ 10

or add as many enroute checkpoints as you need where winds are available.

It's more accurate than averaging the departure/destination winds. (In the example, the average would be 260 @ 7. You'd end up a bit off course to the south.)

I was speaking to fuel planning not course selection.

I would hope if he/she was trying to determine course corrections VFR then he/she was also plotting visual checkpoints or tracking a navigation aid.

Good point, regardless.

 

[MBDiagMan]

I was speaking to fuel planning not course selection.

I would hope if he/she was trying to determine course corrections VFR then he/she was also plotting visual checkpoints or tracking a navigation aid.

Good point, regardless.

That's where the judgment or fudge factor comes in. After looking at winds along the route, try to average them out by looking at the big picture and plug that in for a shot at figuring ground speed, and thus fuel usage. THEN add some fuel in the tanks for safety.

That said, my favorite fuel management technique is taking off with topped off tanks.

 

[Alexb2000]

If I'm at 7500 (airport is at 5100) and the lowest available winds is at 9000, what would I use as my wind for calculations?

And if the origin airport is different than the destination airport, how is that factored into the navigation?

Thanks,
Jamie

When I do flight planning for a long trip I don't really care much about the reported enroute ground winds as I do the winds aloft. I see calm winds at an airport with 30-40 2K above all the time.

I would look at the winds aloft at 9,12,15 all along the route of flight trying to find a trend. If the winds are steadily increasing from the same direction as you go higher then the obvious answer is to fly higher if you are flying with the wind and the increases are worthwhile. If going against I will look for a shear layer if any. The altitude the direction and intensity changes is usually a clue. If that altitude is at say 9 then I might fly just under that level to minimize terrain effect (turbulence, etc.), and get a little speed from being higher. One last thing pay attention to the winds and ride conditions on the climb out especially when flying against the wind. If you get to your planned altitude and don't like it, then having written down (or remembered) another altitude that was good saves a lot of time hunting around.

If you have XM, the winds function alone can pay for the subscription in fuel savings.

Also, before I burn the fuel for a climb, I'll be listening on the radio for someone else around me at the higher altitude, then just ask them for a ride report and winds.

 

[poadeleted20]

First, when you're below the lowest level for which winds aloft are forecast, you have to use a bit of judgement. There are often significant differences in the surface wind and the first wind aloft. If the base of the first cloud layer is below the first wind aloft, the wind below that layer is probably more like the surface wind than the first wind aloft. In that case, compare your cruise altitude to the base of the first cloud layer, and use the more appropriate wind. Otherwise, just interpolate. It's all guesswork, and you'll update your forecast wind with your computed actual wind once airborne, anyway.

As for which reporting station's wind to use, do it leg by leg (i.e., checkpoint to checkpoint if you're going straight-line), and use the wind from the closest station for that leg.

 

[pilotod]

I'm going to read all this. I posted right before a solo cross-country this morning and got to read a couple of the comments. And now at 7:31pm I can't remember what my CFI said in response to the same question. I completed the flight plan using KDEN winds aloft at 9000 ft. Needless to say...I didn't keep track of my time, missed some of my checkpoints but had a hell of a good time! When I flew over KFMM I thought this is hilarious! Finding a landing strip that looks just like a road takes some real practice.....almost a needle in a haystack kind of thing.

I recorded the last half of my flight using cloudahoy on my iphone.

http://www.cloudahoy.com/cgi-bin/fltShare.cgi?share=1KcRnfyCEKBzJyuMLr7es

Thanks for your responses!

And I don't know how on earth I remembered to close my flight plan but did. My CFI turns his watch around to remind him. I don't wear a watch...oh well.

Jamie

 

[kgruber]

Interpolate.

Take destination and departure winds and average the speed and direction.

Take winds aloft and winds on the ground and again average the speed and direction.

Close enough for hand grenades, horseshoes and flight planning. Seems counter intuitive to plan fuel that sloppily but that is why we are required to land with minimum fuel reserves. 30 minutes for fixed wing VFR.

Example -

Departure winds 270 at 14
Destination winds 280 at 10

Plan for 275 at 12.

I believe we are required to "takeoff" with minimum fuel reserves.

""""Sec. 91.151 — Fuel requirements for flight in VFR conditions.

(a) No person may begin a flight in an airplane under VFR conditions unless (considering wind and forecast weather conditions) there is enough fuel to fly to the first point of intended landing and, assuming normal cruising speed—
(1) During the day, to fly after that for at least 30 minutes; or

(2) At night, to fly after that for at least 45 minutes.

(b) No person may begin a flight in a rotorcraft under VFR conditions unless (considering wind and forecast weather conditions) there is enough fuel to fly to the first point of intended landing and, assuming normal cruising speed, to fly after that for at least 20 minutes.""""

 

[pilotod]

I should say this...my CFi decided to top off the tanks before departing. That gave me 3 hours of lost flying fuel. Man, I had a reserve today. Is that joker fuel?
Jamie

 

[EppyGA]

I'm going to read all this. I posted right before a solo cross-country this morning and got to read a couple of the comments. And now at 7:31pm I can't remember what my CFI said in response to the same question. I completed the flight plan using KDEN winds aloft at 9000 ft. Needless to say...I didn't keep track of my time, missed some of my checkpoints but had a hell of a good time! When I flew over KFMM I thought this is hilarious! Finding a landing strip that looks just like a road takes some real practice.....almost a needle in a haystack kind of thing.

I recorded the last half of my flight using cloudahoy on my iphone.

http://www.cloudahoy.com/cgi-bin/fltShare.cgi?share=1KcRnfyCEKBzJyuMLr7es

Thanks for your responses!

And I don't know how on earth I remembered to close my flight plan but did. My CFI turns his watch around to remind him. I don't wear a watch...oh well.

Jamie

You might not want to have cloudahoy running going to or from your home.

Also believe they don't give winds aloft for anything within 2500' of ground level.

 

[pilotod]

I noticed cloudahoy followed me home. Stalker app warning!

Jamie

 

[jaybee]

I believe we are required to "takeoff" with minimum fuel reserves.

""""Sec. 91.151 — Fuel requirements for flight in VFR conditions.

(a) No person may begin a flight in an airplane under VFR conditions unless (considering wind and forecast weather conditions) there is enough fuel to fly to the first point of intended landing and, assuming normal cruising speed—
(1) During the day, to fly after that for at least 30 minutes; or

(2) At night, to fly after that for at least 45 minutes.

(b) No person may begin a flight in a rotorcraft under VFR conditions unless (considering wind and forecast weather conditions) there is enough fuel to fly to the first point of intended landing and, assuming normal cruising speed, to fly after that for at least 20 minutes.""""

Correct, I did not quote the regs verbatim.

However, for fun - if we don't take the words literally right out of the page and we flight plan and fly to point of intended landing and then land, how much fuel should you have in the tank

 

[bobmrg]

Correct, I did not quote the regs verbatim.

However, for fun - if we don't take the words literally right out of the page and we flight plan and fly to point of intended landing and then land, how much fuel should you have in the tank

It is my fervent wish that every pilot land with at least 30 minutes worth of fuel on board, no matter what the regs call for. Idiots who run out of gas and make the six o'clock news make the rest of us look bad.

Bob Gardner

 

[TMetzinger]

Interpolate.

Take destination and departure winds and average the speed and direction.

Take winds aloft and winds on the ground and again average the speed and direction.

Close enough for hand grenades, horseshoes and flight planning. Seems counter intuitive to plan fuel that sloppily but that is why we are required to land with minimum fuel reserves. 30 minutes for fixed wing VFR.

Example -

Departure winds 270 at 14
Destination winds 280 at 10

Plan for 275 at 12.

The requirement is for planning, not for operations. If you plan for 30 min reserves and land with 15, you haven't broken any rules. Most rental agencies have their own policies. Ours requires that you LAND with one hour in the tanks. And they did revoke someone's privileges once when the next user (CFI) found only 30 minutes fuel aboard the airplane when he went out to preflight it.

 

[poadeleted20]

The requirement is for planning, not for operations. If you plan for 30 min reserves and land with 15, you haven't broken any rules.

...other than the unwritten one against doing dumb things. My personal standard for the last 30 years has been to stop and refuel if at any point it appears I will not reach my destination with at least 60 minutes on board. Three incidents in my first 10 years of flying (one in 1974 in which we landed with 9 minutes of fuel remaining) convinced me of the need to establish that standard.

 

[Alexb2000]

The requirement is for planning, not for operations. If you plan for 30 min reserves and land with 15, you haven't broken any rules. Most rental agencies have their own policies. Ours requires that you LAND with one hour in the tanks. And they did revoke someone's privileges once when the next user (CFI) found only 30 minutes fuel aboard the airplane when he went out to preflight it.

Regs are one thing, but I agree we should put more thought into it that that. Instead of a hard fast rule, in my case it depends, with 30 min. minimum left on landing as my personal minimum amount.

I say it depends, because it changes based on where I fly. In a metropolitan area with an airport no more than 10 miles in all directions, I'll land with 30 mins. In the mountains when the nearest alternate is across a pass and 70 miles, I'll want a lot more. I believe the same thought should be applied to IFR ops as well.

 

[Pilawt]

There are often significant differences in the surface wind and the first wind aloft.

I saw a graphic demonstration of that last month over Kelso WA on the way home from a New Years Day breakfast. I was flying into a strong headwind, but at the airport directly below there was a stiff breeze down the runway in the opposite direction:

On the subject of "Winds aloft but I'm not that high," an airline pilot friend sent me this photo this morning. His transpacific flight arrived an hour early.

 

[TMetzinger]

Jamie,

Well, you see one of the many issues with this forecast product. As I've said many times in the past, I really do wish the FAA/NWS would abolish the FBWinds forecast. It's temporal and spatial resolution are horrible and this can result in serious errors, especially when the weather is changing. Most pilots don't realize that it has no amendment criteria either. So no matter how far from reality the forecast is, you are stuck with it. Once my student passes his/her checkride, I try to get them to quickly transition away from this guidance.

What do you transition them to?

 

[HPNPilot1200]

...other than the unwritten one against doing dumb things. My personal standard for the last 30 years has been to stop and refuel if at any point it appears I will not reach my destination with at least 60 minutes on board. Three incidents in my first 10 years of flying (one in 1974 in which we landed with 9 minutes of fuel remaining) convinced me of the need to establish that standard.

I subscribe to the same philosophy with the exception that if it is good VFR (CAVU), I feel comfortable landing with 30-45 minutes of reserves.

 

[jaybee]

The requirement is for planning, not for operations.

I feel like I'm having deja vu

 

[gismo]

Correct, I did not quote the regs verbatim.

However, for fun - if we don't take the words literally right out of the page and we flight plan and fly to point of intended landing and then land, how much fuel should you have in the tank

You should have an hour's worth or more for safety's sake but you're not required to have any. It probably does help to have enough to taxi to the fuel pump or hangar though.