How close will you get to empty?

[Lon Stratton]

The last hour is for me. Not for flight.

Full tanks = 5 hours
4 hours = Empty

 

[Bob Noel]

In your opinion, why did the FAA write "operate a civil aircraft" in 91.167 but "begin a flight" in 91.151? If they meant the two rules to have the same meaning, they would presumably have used the same words in both of them.

the fallacy (not being snide) is that the people writing the rules were capable enough to make that difference deliberate or didn't think it meant two different things or didn't think the differences were important. I've worked with people that considered "impact" and "effect" to be synonymous and others that those two words were completely different.

 

[Doc Holliday]

In your opinion, why did the FAA write "operate a civil aircraft" in 91.167 but "begin a flight" in 91.151? If they meant the two rules to have the same meaning, they would presumably have used the same words in both of them. (I continue to couch all of this in the context of "VFR conditions" and "IFR conditions" being nonsensical phrases, the use of which might rebut the presumption about other parts of these regulations having been drafted with a close match between intended and actual meaning.)

Assuming the FAA meant what they wrote, then in your scenarios...

If you realize you are going to land with 40 minutes of fuel and you are either under IFR or in IMC (whatever "IFR conditions" means), you have several options. You could tell ATC that you have minimum fuel, declare an emergency, request priority handling, get out of "IFR conditions" by hook or by crook, and/or exercise your prerogative under 91.3. Same answer if you will land with exactly 45 minutes of fuel remaining and get waved off into the clouds.

As far as the purpose of reserve fuel, I would say that it's to prevent these types of minor emergencies from becoming major catastrophes.

You would have to go back into the regulation achieves to find out why they are written differently. Chances are they were written at different times and the people that wrote them chose the different methods. Other than that we are guessing.

But the intent is the same, it is a planning number, and once the aircraft is in flight there is no prohibition to burn into the reserve. Notice they didn't write "No aircraft can end a flight with less than....."

 

[mark.staggs]

hmmm, I seem to recall the fuel reserve requirements applied to departing. Landing with even just 1 minute of fuel is legal, isn't it?

Or did that requirement change when I wasn't looking?

Yep. And that's what I was saying. I landed with 30 minutes just has I had planned before I departed for home.

 

[midlifeflyer]

hmmm, I seem to recall the fuel reserve requirements applied to departing. Landing with even just 1 minute of fuel is legal, isn't it?

Or did that requirement change when I wasn't looking?

Well, here's what the reg actually says:

No person may operate a civil aircraft in IFR conditions unless it carries enough fuel (considering weather reports and forecasts and weather conditions) to--​

(1) Complete the flight to the first airport of intended landing;​

(2) Except as provided in paragraph (b) of this section, fly from that airport to the alternate airport; and​

(3) (3) Fly after that for 45 minutes at normal cruising speed or, for helicopters, fly after that for 30 minutes at normal cruising speed.​

Note, "operate," not "depart." The only case I've read on the subject (the pilot won on that point) suggests that landing with that 1 minute doesn't automatically mean a violation, but it might. You can read it and come to your own conclusion. FAA v Eden

 

[Doc Holliday]

Well, here's what the reg actually says:

No person may operate a civil aircraft in IFR conditions unless it carries enough fuel (considering weather reports and forecasts and weather conditions) to--​

(1) Complete the flight to the first airport of intended landing;​

(2) Except as provided in paragraph (b) of this section, fly from that airport to the alternate airport; and​

(3) (3) Fly after that for 45 minutes at normal cruising speed or, for helicopters, fly after that for 30 minutes at normal cruising speed.​

Note, "operate," not "depart." The only case I've read on the subject (the pilot won) suggests that landing with that 1 minute doesn't automatically mean a violation, but it might. You can read it and come to your own conclusion. FAA v Eden

Inasmuch as the Administrator did not establish that respondent's planned flight time was invalid or unreasonable, it is of no consequence, for purposes of determining whether respondent began the flight with the fuel reserves required by FAR section 91.167, that the flight took longer than was anticipated and, as a result, the aircraft landed with less fuel than had been estimated.

 

[MauleSkinner]

(I continue to couch all of this in the context of "VFR conditions" and "IFR conditions" being nonsensical phrases,

Why are they nonsensical phrases?

 

[midlifeflyer]

Why are they nonsensical phrases?

I don't know if they are nonsensical, but based on years of posts and discussions, they do seem to lead to a lot of confusion. Even their regulatory use is a bit inconsistent. For example, the P/CG definition:

VFR CONDITIONS- Weather conditions equal to or better than the minimum for flight under visual flight rules.​

IOW, VFR cloud clearances, which depend on the airspace you are in. It's used that way a lot, but not always. An example is the lost com rules

VFR conditions. If the failure occurs in VFR conditions, or if VFR conditions are encountered after the failure, each pilot shall continue the flight under VFR and land as soon as practicable.​

Since there is no "VFR" in the flight levels (waivers excepted), does that mean if you are flying at FL200 on an absolutely clear day and have a "pure" comm failure, this provision does not apply and you should continue the flight under IFR?

 

[Ed Haywood]

Well, here's what the reg actually says:

No person may operate a civil aircraft in IFR conditions unless it carries enough fuel (considering weather reports and forecasts and weather conditions) to--​

(1) Complete the flight to the first airport of intended landing;​

(2) Except as provided in paragraph (b) of this section, fly from that airport to the alternate airport; and​

(3) (3) Fly after that for 45 minutes at normal cruising speed or, for helicopters, fly after that for 30 minutes at normal cruising speed.​

Note, "operate," not "depart." The only case I've read on the subject (the pilot won) suggests that landing with that 1 minute doesn't automatically mean a violation, but it might. You can read it and come to your own conclusion. FAA v Eden

To me, this clearly implies that if conditions change during an IFR flight such that your fuel calculations come up short of #3, you must divert. Or, adjust power settings to make the numbers work.

 

[Rick A]

I don't like to get under an hour.

Yes, a good operating practice. And when I do land with less than an hour, which is rare (have nearly 8 hours of endurance if needed), most of the fuel remaining is in the tank designated to be used for landing. This prevents any un-porting during the descent (when the nose is lowered and the fuel runs forward), and/or during turbulence to prevent any fuel from sloshing around and sucking up air rather than fuel.

 

[iamtheari]

Why are they nonsensical phrases?

VFR and IFR are rulebooks, not weather conditions. VMC and IMC are weather conditions, which are referred to in those rulebooks but are not rulebooks on their own. You can fly under IFR in VMC. In some instances, you can fly under VFR in IMC. We've had multiple threads where that has come up and I think they always end with a black-and-white answer about what those terms mean and what you can do. On the other hand, the terms "VFR conditions" and "IFR conditions" are used in the FARs, but I think they are only defined in secondary sources like the Pilot/Controller Glossary, and their use mostly leads to confusion and uncertainty.

Here's an example of real nonsense. Section 91.167 requires a 45-minute reserve to operate "in IFR conditions," not for flight under instrument flight rules. For a moment, let's take it as understood that this requirement is only for the amount of fuel you need to begin a flight, and you can legally burn into your reserve fuel during the flight. Imagine you get an IFR clearance, take off in VMC, cruise in VMC, and approach an airport that is currently socked in with a 200-foot ceiling and 1-mile visibility and has been forecast to remain socked in from yesterday morning until tomorrow night. Because you are not beginning the flight in "IFR conditions," do the 91.151 VFR reserve requirements apply? If you have to follow the IFR reserve requirements for this flight, what language in 91.151 and/or 91.167 imposes that requirement?

There are two possibilities here, either or both of which correct that nonsense. First, 91.167 could impose a reserve requirement for all flights operated under instrument flight rules, regardless of weather conditions during the flight. But that's not how it's written. Second, 91.167 could impose a reserve requirement for any time when a flight operates in instrument meteorological conditions, which is kind of how it's written but not how it is understood by, it seems, most pilots, the FAA, or the courts.

This loose drafting style is why I concede that 91.167 might not carry its literal meaning. I think that flying our imaginary flight above while burning into your 91.151 VFR reserve fuel right up until you exhaust your fuel on the missed approach and crash is reckless and insane, but it might be legally defensible as far as reserve fuel requirements go. (Note that Mr. Eden only "won" that part of his case, and lost it on all the other illegal and stupid things he did.)

Back to the topic of the thread, then ...

It's a good idea for both your certificate and your health to plan better than legal reserves, verify you still have reserve fuel while you are in the air, and land with extra gas. My own personal minimums are to take off and remain very confident in landing with at least 1 hour of reserve fuel in the tanks, whether VFR or IFR. More if I am going someplace without a dense selection of alternates. Look at KBDG-KFLG, a 180-mile segment without available fuel stops anywhere near the route.

I will go below that 1-hour reserve in some conditions, such as a local flight in the pattern in severe clear with forecast winds far below my personal limits. But it only takes one closed runway, one "oh crap what is up with that wind?" go-around, or one day of just being off your game to find yourself making a cross-country flight to a last-minute diversion airport where the runway is open, wind is more favorable, etc. and wishing you had some extra gas.

Looking at it another way: There are a lot of rules in my profession that work the same as the FARs. You need to learn exactly where the line is in order to pass a test, but after the test you will live a much longer and happier life if you stay so far away from that line that you forget what it looks like.

 

[MauleSkinner]

VFR and IFR are rulebooks, not weather conditions. VMC and IMC are weather conditions, which are referred to in those rulebooks but are not rulebooks on their own. You can fly under IFR in VMC. In some instances, you can fly under VFR in IMC. We've had multiple threads where that has come up and I think they always end with a black-and-white answer about what those terms mean and what you can do. On the other hand, the terms "VFR conditions" and "IFR conditions" are used in the FARs, but I think they are only defined in secondary sources like the Pilot/Controller Glossary, and their use mostly leads to confusion and uncertainty.

So FAR 1 is a “secondary source”? Those discussions generally end in a black-and-white answer because the definitions are clear. As @midlifeflyer indicated, there is some variance in application in regulatory language, but you’d also have to admit that the regulatory example given generates tremendous confusion on its own.

I think the biggest issue with the terms “IFT conditions” and “VFR conditions” is that we live in a world where people use terms to mean whatever they want, to the point where they’re actually redefined (literally, for example, can mean either of two almost exact opposite things,) and so using terms as defined by the FAA is considered incorrect. That’s not a problem with the terms, that’s a user problem.

Here's an example of real nonsense. Section 91.167 requires a 45-minute reserve to operate "in IFR conditions," not for flight under instrument flight rules. For a moment, let's take it as understood that this requirement is only for the amount of fuel you need to begin a flight, and you can legally burn into your reserve fuel during the flight. Imagine you get an IFR clearance, take off in VMC, cruise in VMC, and approach an airport that is currently socked in with a 200-foot ceiling and 1-mile visibility and has been forecast to remain socked in from yesterday morning until tomorrow night. Because you are not beginning the flight in "IFR conditions," do the 91.151 VFR reserve requirements apply? If you have to follow the IFR reserve requirements for this flight, what language in 91.151 and/or 91.167 imposes that requirement?

Why not take it to mean what it says? If you are not in IFR conditions, you need that reserve. If not, you don’t.

There are two possibilities here, either or both of which correct that nonsense. First, 91.167 could impose a reserve requirement for all flights operated under instrument flight rules, regardless of weather conditions during the flight. But that's not how it's written. Second, 91.167 could impose a reserve requirement for any time when a flight operates in instrument meteorological conditions, which is kind of how it's written but not how it is understood by, it seems, most pilots, the FAA, or the courts.

This loose drafting style is why I concede that 91.167 might not carry its literal meaning. I think that flying our imaginary flight above while burning into your 91.151 VFR reserve fuel right up until you exhaust your fuel on the missed approach and crash is reckless and insane, but it might be legally defensible as far as reserve fuel requirements go. (Note that Mr. Eden only "won" that part of his case, and lost it on all the other illegal and stupid things he did.

I didn’t notice anything in Mr. Eden’s case where they stated what the weather was at his destination. If the weather was such that he had to fly an approach, I have doubts that particular violation would have been reversed.

 

[iamtheari]

So FAR 1 is a “secondary source”? Those discussions generally end in a black-and-white answer because the definitions are clear. As @midlifeflyer indicated, there is some variance in application in regulatory language, but you’d also have to admit that the regulatory example given generates tremendous confusion on its own.

I stand corrected about FAR 1 defining IFR conditions. It also defines Special VFR conditions. But it does not define VFR conditions, even though it uses that term in the definition of IFR over-the-top.

I think the biggest issue with the terms “IFT conditions” and “VFR conditions” is that we live in a world where people use terms to mean whatever they want, to the point where they’re actually redefined (literally, for example, can mean either of two almost exact opposite things,) and so using terms as defined by the FAA is considered incorrect. That’s not a problem with the terms, that’s a user problem.

I think that my biggest problem is that the FAA is one of the problematic (ab/mis)users of these terms.

Why not take it to mean what it says? If you are not in IFR conditions, you need that reserve. If not, you don’t.

That's what I posted at #73 above. But numerous other posts in this thread disagree with taking 91.167 to mean what it says. And a regulatory gap exists if 91.167 means what it says. If you start a flight in IMC and break out into VMC, what fuel reserves apply afterward? Or does that not matter, because by having a 45-minute reserve at all times of the operation prior to breaking out you will logically meet or exceed the fuel reserve requirement that would have applied had you begun the flight in VMC?

I didn’t notice anything in Mr. Eden’s case where they stated what the weather was at his destination. If the weather was such that he had to fly an approach, I have doubts that particular violation would have been reversed.

Good point. Perhaps he was in VMC and thus not subject to 91.167, which on its face only applies to operating in IFR conditions. But the court's decision doesn't frame the issue that way. The decision was written in terms of "for purposes of determining whether respondent began the flight with the fuel reserves required by FAR section 91.167." I think that, if the 91.167 violation had affected the outcome of the case, they might have analyzed the law and facts more closely. That sometimes happens in court: If you have ten ways to lose, the courts (and especially courts sitting in an appellate role) will skim over the harder issues and tell you that you lose because of an easy one.

 

[Stewartb]

For most of my flying, the approach on both ends has been over water and very inhospitable terrain. A half hour’s worth of fuel shows empty on my gauges and my FS-450 doesn’t settle the “what if” very well. I’m good with carrying an extra 50# of fuel to keep the gauges bobbing. I’m in the one hour crowd.

 

[Ed Haywood]

One thing I noticed: a lot of the responses state how much fuel they have in hours.

How many of you use different planning factors for different power settings?

For example, my aircraft burns 10 gph at 75% HP leaned for best power. 40 gallons on board gives me 4 hours endurance, so I plan for 3 hours max.

However, my engine monitor has allowed me to refine my calculations. I burn 7 gph at 65% HP leaned for best economy. That is 5.7 hours endurance. As a result, I will sometimes plan for legs as long as 4 hours if I want to stay aloft.

 

[William Pete Hodges]

I like an hour…first hour’s burn in airplanes where it’s different per hour. I’ve planned less than that in airplanes that didn’t have enough capacity, but the only times I’ve burned into whatever my reserve was, I had at least declared minimum fuel.

Well, I should say “knowingly” burned into my reserve. One time I wasn’t paying attention to my fuel, and ended up landing at a nearby farm strip and stealing some gas. (When I told him about it later, he didn’t want me to pay for it, so is it still stealing?)

Soon to be student pilot here with a question.

JeffinNV
Mauleskinner's advice is sound. My Mooney can climb to 10,000 feet in about 20 minutes. In that time the average fuel burn is about 14 GPH, more at low altitude and less above. So I figure the first 20 minutes burns about 5 Gallons, then 40 minutes at about 8-GPH so my first hour including ground operations is about 11 gallons. After that it is about 8 GPH so a 3 hour flight would burn about 11+8+8 = 27 gallons. My actual burn is usually about 25, so I am burning less during the descent phase, but for a quick analysis I don't worry about that. 27/3 = 9, so my minimum takeoff fuel for that flight would be 36 gallons or more. When I make this flight, I am landing where fuel is not available, so I take off with 52 gallons and land with about 25-27 gallons left in the tank. That lets me takeoff again and get partway home before stopping for fuel at a decent price. I'm not going to climb to 10,000 on the first leg because I have to stop, so maybe 3500-4500 feet. The first hour burn is about 9, and the second hour is about 8, making 17 total. I have to stop for fuel in less than 2 hours to keep my reserve. At lower altitudes I might also reduce power, save some fuel, and look for my fuel stop sooner. It becomes second nature after awhile. When I stop for fuel I get a good price, so I fill it up to top off, especially if that price beats my home airport. I'll probably land with more than 30 in the tank. No problem, I'll use it later.

 

[brcase]

anyone remember the story (I believe the story to be non-fiction) of the guy flying an arrow, planned a fuel stop but have favorable winds. So he pressed on to his destination. He landed and the engine quit on roll out.

anyone remember the story (I believe the story to be non-fiction) of the guy flying an arrow, planned a fuel stop but have favorable winds. So he pressed on to his destination. He landed and the engine quit on roll out.

No but I remember the Cherokee that crashed (stopped) within 500 feet of the threshold

looks like about 3 passengers and flight time was 2hr 40min.

 

[Eric Pauley]

One thing I noticed: a lot of the responses state how much fuel they have in hours.

How many of you use different planning factors for different power settings?

For example, my aircraft burns 10 gph at 75% HP leaned for best power. 40 gallons on board gives me 4 hours endurance, so I plan for 3 hours max.

However, my engine monitor has allowed me to refine my calculations. I burn 7 gph at 65% HP leaned for best economy. That is 5.7 hours endurance. As a result, I will sometimes plan for legs as long as 4 hours if I want to stay aloft.

For cross-country flights I will absolutely plan around expected fuel burn rates for the actual flight. I want around 1.5h reserve, with that reserve being at a mix of cruise and climb. In the Arrow that works out to around 15gal in reserve.

In flight during my routine fuel check I look at my expected reserve at destination (this is based on current fuel burn so it's only accurate once in cruise). If this is substantially lower than my planning or below my reserve requirements then it's time to make an alternate plan.

It helps that the Arrow III has 72 gallons and easily cruises at 9gph, so the range is usually longer than I'd want to spend in the air. Looking back the longest flight I've planned was 675nm, which is doable with the above reserves even with a tailwind. The planning becomes more pertinent if you're filling partway for W&B.

As an example I flight planned for the solar eclipse last year. That required partial tanks for W&B but also included extended loiter time, which I planned at lower fuel flow. This all requires consistent monitoring of both totalizer and tank readings to ensure the planned reserve will pan out.

 

[MauleSkinner]

How many of you use different planning factors for different power settings?

A follow-up question would be how many of you use more than one “normal cruise speed”?

Since most people seem to prefer more reserve fuel than the regulation requires, I think those answers have a level of precision that would only come up when being investigated for a violation. How much fuel I want when I land has little to do with the fuel I’ve burned, it’s the fuel I’m going to burn if I can’t land.

 

[midlifeflyer]

One thing I noticed: a lot of the responses state how much fuel they have in hours.

How many of you use different planning factors for different power settings?

For example, my aircraft burns 10 gph at 75% HP leaned for best power. 40 gallons on board gives me 4 hours endurance, so I plan for 3 hours max.

However, my engine monitor has allowed me to refine my calculations. I burn 7 gph at 65% HP leaned for best economy. That is 5.7 hours endurance. As a result, I will sometimes plan for legs as long as 4 hours if I want to stay aloft.

I'm very conservative about this. The Reference sheet at the end of my personal checklists have system and performance information. For endurance with my 1-hour reserve, the number is based on total fuel capacity and the worst burn rate. Since 99% of my flights involve full fuel, my preferred power setting is less than max, and my max leg in the air is 3-3.5 hours, I don't need to go any further. If a parameter change requires an actual calculation, I'll go further.

 

[robin ardoin]

One thing I noticed: a lot of the responses state how much fuel they have in hours.

How many of you use different planning factors for different power settings?

For example, my aircraft burns 10 gph at 75% HP leaned for best power. 40 gallons on board gives me 4 hours endurance, so I plan for 3 hours max.

However, my engine monitor has allowed me to refine my calculations. I burn 7 gph at 65% HP leaned for best economy. That is 5.7 hours endurance. As a result, I will sometimes plan for legs as long as 4 hours if I want to stay aloft.

I plan assuming a conservative maximum anticipated fuel burn and want 1hr reserve at that power setting. I can drop the burn by 7gph+ by going LOP and reducing TAS from 175-180kts or a little better to 162-165kts. The one hour of max burn fuel can then be stretched quite a bit and that gives me comfort.

 

[Kiddo's Driver]

I intentionally ran the pilot side dry and then arrived at the pump with 40 minutes remaining in the passenger side last week. Spent the last 20 minutes flying very near the airport to run the fuel down. It is nice to have accurate fuel gauges. The insides of the fuel tanks also feature factory-installed measurement marks in liters and gallons, allowing you to check your fuel levels on the ground manually and routinely compare them to the readings displayed by the gauges.

Normal flying? I like having at least an hour left in the day and more at night/IFR.

 

[Doc Holliday]

For the work airplane I use the NBAA recommendations.

NBAA provides guidelines for fuel reserves for turbine aircraft, which are more extensive than
FAA Part 91 regulations, including a final reserve of 30 minutes at 1,500 feet and 5% contingency fuel for unforeseen events, plus additional time for a missed approach, holding, and diversion. While the NBAA guidelines are often a starting point for the Captain's decisionon fuel quantity, the ultimate responsibility for ensuring safe fuel reserves rests with the Captain.
NBAA Fuel Reserve Guidelines (for turbine aircraft)
The NBAA's recommendations are more comprehensive than the minimum regulatory requirements and are designed for real-world flight planning:

• Final Reserve Fuel:This is the minimum fuel required to fly for 30 minutes at 1,500 feet above the destination or alternate airport in standard conditions.
• Contingency Fuel:An additional 5% of the total planned trip fuel is recommended to account for unforeseen factors like wind, navigation errors, and individual aircraft variance in fuel consumption.
• Holding Fuel:Fuel to hold for 5 minutes while waiting for ATC clearance after a missed approach.
• Missed Approach and Diversion Fuel:The plan must include enough fuel to execute a missed approach, hold for a short period, and then fly to the alternate.
• APU Fuel:If the APU (Auxiliary Power Unit) is used on the ground or in flight, fuel for its operation must also be accounted for.

Regulatory vs. NBAA Minimums

• Federal Aviation Regulations (FARs):
  • Part 91 (VFR): A minimum of 30 minutes of fuel at normal cruising speed for day flights and 45 minutes for night flights for airplanes.
  • Part 91 (IFR): A minimum of 45 minutes of fuel at normal cruising speed for airplanes.
• NBAA Guidelines:The NBAA's recommendations go beyond the regulatory minimums and are intended to provide a more conservative and practical approach to fuel reserve planning for turbine aircraft.

Captain's Responsibility

• The Captain is ultimately responsible for the decision on how much fuel to carry for a flight.
• The Captain must consider factors beyond the minimum requirements, such as weather conditions, aircraft performance, and any potential delays, to ensure a safe flight

 

[Ed Haywood]

I intentionally ran the pilot side dry and then arrived at the pump with 40 minutes remaining in the passenger side last week. Spent the last 20 minutes flying very near the airport to run the fuel down. It is nice to have accurate fuel gauges. The insides of the fuel tanks also feature factory-installed measurement marks in liters and gallons, allowing you to check your fuel levels on the ground manually and routinely compare them to the readings displayed by the gauges.

Smart to do that. What did the engine do when the tank ran dry?

 

[midwestpa24]

One thing I noticed: a lot of the responses state how much fuel they have in hours.

How many of you use different planning factors for different power settings?

For example, my aircraft burns 10 gph at 75% HP leaned for best power. 40 gallons on board gives me 4 hours endurance, so I plan for 3 hours max.

However, my engine monitor has allowed me to refine my calculations. I burn 7 gph at 65% HP leaned for best economy. That is 5.7 hours endurance. As a result, I will sometimes plan for legs as long as 4 hours if I want to stay aloft.

Not exactly. For instance in the Comanche, I know it burns 14 gph, can sometimes get it down to 13.5. I flight plan for 15 gph. Makes for easy math since the mains hold 30 gallons (2 hours each) and the aux hold 15 gallons (1 hour each).

I've never had hurt feelings landing with more fuel than planned.

For what its worth, from home base Iowa at 155 kts I can reach darn near most places between the Rockies and Appalachians in 5 hours. I can only think of one trip I have ever done that required a fuel stop, although that stop was voluntary and more for food and restroom than fuel. I was showing 4:55 ETE.

 

[Kiddo's Driver]

Smart to do that. What did the engine do when the tank ran dry?

I watched fuel pressure slowly drop as the tank level got really low. During the last couple of minutes, the needle moved a bit more quickly.
When the fuel pressure needle just barely touched the red marking, the engine rpm dropped.
I already had my hand on the fuel tank valve, so I moved it to the other tank, turned on the electric fuel pump, and moved the mixture knob to full rich.
RPM recovered quickly.

 

[Daleandee]

I've never had hurt feelings landing with more fuel than planned.

 

[Stewartb]

To the fuel consumption variable? When fuel is approaching low? I go to economy cruise and lean more aggressively than normal. My reserves are based on normal cruise, my actual will be a little better.

 

[Ed Haywood]

I watched fuel pressure slowly drop as the tank level got really low. During the last couple of minutes, the needle moved a bit more quickly.
When the fuel pressure needle just barely touched the red marking, the engine rpm dropped.
I already had my hand on the fuel tank valve, so I moved it to the other tank, turned on the electric fuel pump, and moved the mixture knob to full rich.
RPM recovered quickly.

Great training. Now you'll recognize when you don't expect it. Next time, run that tank bone dry. You'll probably get a couple of surges, like slurping mixed cola and air though a soda straw. I wish someone had done that with me.

 

[MauleSkinner]

I've never had hurt feelings landing with more fuel than planned.

I used to fly a guy who would complain about it.

 

[iamtheari]

Great training. Now you'll recognize when you don't expect it. Next time, run that tank bone dry. You'll probably get a couple of surges, like slurping mixed cola and air though a soda straw. I wish someone had done that with me.

And it will also take about an hour and forty-five minutes after you switch tanks and turn on the boost pump for the engine to come back to life. (Actual elapsed time: not long enough to impress a bull rider.)

 

[frfly172]

Half tanks as I only have 23 usable to start with.

 

[455 Bravo Uniform]

1 hour, or 15 gallons conservatively. With each tank being 40 gallons, that’s like a 1/2 inch (if that) in each tank. That seems awfully dry and unnerving. Especially with bladders that might have wrinkles. So I like to keep no lower than 20 gallons at shutdown.

If I’m landing away from home I do worry “what if the fuel went inop at this field”.

I’m at 70% power for all XCs.

 

[asicer]

How many of you use different planning factors for different power settings?

Me.

A follow-up question would be how many of you use more than one “normal cruise speed”?

Me.

If my intermediate waypoints are looking a bit off, I'll throttle back to my secondary setting. If anything, by throttling back maybe I won't get so far away from my diversionary airport in such a hurry.

 

[MooneyDriver78]

Since I always fly high enough I’m limited by air (8000+), it works out the higher I fly, the slower but the less gph, kinda balances out.

 

[M20K]

Since I always fly high enough I’m limited by air (8000+), it works out the higher I fly, the slower but the less gph, kinda balances out.

Not really the way it works.... Your Indicated Airspeed may be lower. But do a quick review about True Airspeed when you go higher.

Pending where you are, get down as low as you can and check your IAS and your GPS speed. Then go up to 10K and check your IAS and your GPS speed. Easy way to factor in winds in this test is to turn on the Autopilot and dial in N for 3 min, E for 3, min, S for 3 min and W for 3 min and average out the speed for low and high. (Calculate the same power per the POH for the Altitude and temps.)

 

[iamtheari]

Not really the way it works.... Your Indicated Airspeed may be lower. But do a quick review about True Airspeed when you go higher.

Pending where you are, get down as low as you can and check your IAS and your GPS speed. Then go up to 10K and check your IAS and your GPS speed. Easy way to factor in winds in this test is to turn on the Autopilot and dial in N for 3 min, E for 3, min, S for 3 min and W for 3 min and average out the speed for low and high. (Calculate the same power per the POH for the Altitude and temps.)

Does your plane happen to be turbocharged or turbonormalized?

 

[Albany Tom]

One thing I noticed: a lot of the responses state how much fuel they have in hours.

How many of you use different planning factors for different power settings?

For example, my aircraft burns 10 gph at 75% HP leaned for best power. 40 gallons on board gives me 4 hours endurance, so I plan for 3 hours max.

However, my engine monitor has allowed me to refine my calculations. I burn 7 gph at 65% HP leaned for best economy. That is 5.7 hours endurance. As a result, I will sometimes plan for legs as long as 4 hours if I want to stay aloft.

Ed, I respect your views and agree with most of them, but I have a different take on this one. Possibly because I'm a bit of a baby.

The planes I rent mostly don't have a fuel rate indication. They have a book rate of 8.5 gph, but I use 9 for estimations. And if I'm doing a lot of full power/full rich flight, like pattern work, I actually estimate 11. I round everything up. For longer trips I will use that 8.5 number, but only for cruise. For each stop including the fuel stops I figure a burn rate of 12 for the few minutes on the ground and the climb to altitude. That may sound silly, but 2 up it can take a while for a pa-28-150 to get to 6000 ft or whatever, and that's full power full rich. I just like being conservative.

If I had an engine monitor that I knew was accurate, I could see using that to better estimate the fuel I'd burned so far, padding that number too, but I think I'd also want to have the forward planning be based on a more conservative fuel burn. To do all that, though, I'd have my trip planned with maybe a different stop. So for example, if I were going to fly from Albany to Buffalo I might figure in some Murphy's, that I'll have a 35 knot headwind and average 8.5 gph at low ground speed and so I'll stop in Syracuse for fuel. But if I have the fuel flow meter, and it's happy and my ground speed is high because I have a tail wind, when I get to Syracuse if I still have 1+ hr reserve even if I get a surprise headwind, I might not stop.

Or in other words, I wouldn't treat past experience as future performance, in part because winds change. But again, I'm a bit of a baby.

 

[M20K]

Does your plane happen to be turbocharged or turbonormalized?

That makes no difference in Indicated vs True Airspeed.

Oh... If it is because I suggested 10K, that comes from your saying you fly at 8000 *+*... Pick any high altitdude you want. But the bottom line is you do not fly slower up high.

 

[Kiddo's Driver]

Great training. Now you'll recognize when you don't expect it. Next time, run that tank bone dry. You'll probably get a couple of surges, like slurping mixed cola and air though a soda straw. I wish someone had done that with me.

I’ve done that before on a long leg, at altitude.
I hadn’t learned to watch fuel pressure.
It just kept getting closer to empty.
I got distracted.
Then rpm went way down & I crushed a lump of coal into a diamond.
Still came right back up when I switched tanks & kicked on the pump.