What is a fuel emergency?

[201er]

I found this video extremely useless:

 

It described minimum fuel as not much fuel left and a fuel emergency as an emergency involving fuel. But it made no effort whatsoever to distinguish how much fuel/endurance/range remaining is considered either.

 

So my question is, what is minimum fuel and what is a fuel emergency? Is minimum fuel when you are up against the edge of your reserve? Is it when you've begun to tap into your reserve? Is tapping into your reserve an emergency? What about having a fuel management mishap where you've lost track of how much fuel is left? Is that an emergency?

 

If you take off on a 5 hour, day VFR, xcountry with 5.5 hours of fuel, are you in a minimum fuel condition on arrival? Enroute? How much of an enroute delay would qualify this as a fuel emergency?

 

[Hank]

For ME, minimum fuel is 9 gallons or 1 hour endurance. That's when I like to be on the ground. The closest I've come so far is 11 gal, and I wasn't happy [headwinds at night over E. Kentucky . . . ].

A fuel emergency for me would be approaching this level in an assigned hold, of which I have been given exactly one in the last six years. Flying somewhere that airports are far apart may raise my limit to a higher value, but that just means plan better and fill up! If I overfly several fields with fuel to save a stop, then have to declare an emergency to [hopefully!] not run out of fuel int he air, that is just piss-poor planning!

My dad the Marine taught me the 7 P procedure: Proper Prudent Planning Prevents Piss-Poor Performance. This supposes, however, that one is able to execute the plan. When headwinds, deviations, holds, etc., interrupt The Plan, that's where Plan B comes in. Yes, all Prudent Planning includes a Plan B, and that leads to prevention.

Without watching the video, and relying on my student pilot memory, a fuel emergency means you forgot to fill up and need to land immediately, while minimum fuel is just a way to ask for expedited handling. Both are indications of problems in the left seat, but some are created by genuine, not-previously-know fuel leaks.

[PMcClure]

My plans - let ATC know I have minimum fuel, meaning "please help me out". Or a Fuel Emergency, which means, "get everyone else the hell out of my way, I am pointed at the RR."

Of course, I hope neither of these situations happen as I would have planned a divert well before either situation occurred. But it is possible in a hold. 

[N201MKTurbo]

If you are VFR, just land and buy fuel.

If you are IFR and ATC is vectoring you all over hell and you are into your reserves, you have a fuel emergency and need priority to land somewhere before they run you out of gas.

If you are IFR and winds are greater than forecast and you are not going to make it to your destination, tell ATC you need to change your destination because you are low on fuel. If they say no than you have a fuel emergency. 

[PTK]

24 minutes ago, Hank said:

For ME, minimum fuel is 9 gallons or 1 hour endurance. That's when I like to be on the ground...

As per my POH 8 gal or less is considered critically low and maneuver sensitive.

The lowest I've ever been on an IFR flight is 14 gal total fuel remaining. I've setup my JPI to alarm at 19.

[201er]

Just now, PTK said:

As per my POH 8 gal or less is considered critically low and maneuver sensitive.

The lowest I've ever been on an IFR flight is 14 gal total fuel remaining. I've setup my JPI to alarm at 19.

Ok, sure sure sure. But when would you declare minimum fuel to ATC and when would you declare an emergency?

[PTK]

I think a distinction has to be made between advising ATC that a fuel emergency is possible at some future point in the flight vs. a true emergency that exists now. 

I would declare a fuel emergency if my present fuel situation is unable to support any delay upon reaching my destination.  This requires accurate information of fuel status. IOW I'm not waiting to tell them that my engine will quit any minute now to declare. I'm telling them I can reach my destination without any delay.

[jetdriven]

1 hour ago, PTK said:

 

I would declare a fuel emergency if my present fuel situation is unable to support any delay upon reaching my destination.  This requires accurate information of fuel status. IOW I'm not waiting to tell them that my engine will quit any minute now to declare. I'm telling them I can reach my destination without any delay.

That's the definition of the "minimum fuel" advisory. If you declare an emergency for this well, get ready for a phone call 

[mooniac15u]

http://lessonslearned.faa.gov/Avianca52/INFO_08004.pdf

[201er]

53 minutes ago, mooniac15u said:

http://lessonslearned.faa.gov/Avianca52/INFO_08004.pdf

What I got out of this was:

 

Declare “minimum fuel” when, in your best judgment, any additional delay will cause you to burn into your reserve fuel.

•

Declare a fuel emergency at the point at which, in your judgment, it is necessary for you to proceed directly to the airport at which you intend to land. Declaration of a fuel emergency is an explicit stat ement that priority handling by ATC is necessary and expected.

[201er]

What I still don't get is if arriving at an airport with 30 mins of remaining fuel is an emergency? 15 minutes? Since I never arrive anywhere with less than an hour (and usually much more), my personal caution is different. Since I am unable to accurately measure remaining fuel and fuel totalizer (or gph/timer method) incurs increasing error with partial fill ups and hours flown, I don't even expect the last 5 gallons to be there. Sumping tanks a few times, a few little errors, maybe a small seep, and poof, you're putting in 5 gallons more than you expected on a big fill up. So personally, I would consider 10 gallons calculated remaining to be an emergency because compounded measuring error could mean there are just 5 there. Would an inspection agree with me on that?

 

When I flew to San Marcos in 11 hours non-stop, I burned a bit more gas than expected because of IFR routing and stronger than expected headwinds. Originally I was planning to arrive with about 15 gallons remaining but in fact I arrived with 8 on the totalizer. I was ready to declare minimal fuel or an emergency at any moment. However, I had clear blue skies, abundant enroute airports, altitude, unlimited flat fields, several cross references on fuel, and no traffic. Requesting priority was entirely pointless cause I was #1 inbound anyway. I was confident that I even had enough for a go-around if need be but didn't plan to use it! But I did land with both low-fuel lights on!

 

After the plane was topped off, it turned out that I had 14 gallons remaining and not 8. That was an error of 6 gallons. Could have been the other way! I do try to keep all measurement errors erring to the side of more gas than less, but just goes to show. A 0.2gph error across 11 hours is 2 gallons. Plus the pump could have some small error, how you sump, heck even our understanding of full tanks is erred. Gas expansion with temperature, leaking out the vents when expanding, etc. So in another situation involving delays and weather, can an approximate 10 gallons remaining constitute a fuel emergency when you're measurement accuracy is only +/- 5%?

[cnoe]

3 hours ago, 201er said:

What I got out of this was:

 

Declare “minimum fuel” when, in your best judgment, any additional delay will cause you to burn into your reserve fuel.

Note that this reply is coming from a person who routinely flies with much more fuel than necessary for any given mission, and my personal daytime VFR reserve is a full hour.

But, I think your definition of "minimum fuel" above is too conservative unless you're referring the the "legal reserve" (not your personal reserve). If I declare minimum fuel to ATC and then land with an hour of fuel remaining (day VFR) I'd say I made the declaration in error.

3 hours ago, 201er said:

Sumping tanks a few times, a few little errors, maybe a small seep, and poof, you're putting in 5 gallons more than you expected on a big fill up. So personally, I would consider 10 gallons calculated remaining to be an emergency because compounded measuring error could mean there are just 5 there. Would an inspection agree with me on that?

... after the plane was topped off, it turned out that I had 14 gallons remaining and not 8. That was an error of 6 gallons. A 0.2gph error across 11 hours is 2 gallons.

Have you ever had a gross error like this in the "wrong" direction? It sounds like there's a lot of room for improvement in your k-factor. I routinely see fuel consumption errors of less than ONE gallon when filling to capacity (64 gal. tanks). In your example the error was in excess of 10%! Could you have an old/bad fuel transducer? Or is it just not calibrated?

I'm trying to be helpful, not critical. Some of those high-tech fuel senders may be in order. If I eventually upgrade to a JPI (primary) monitor (900 series) I'd like to add them to my plane.

[MB65E]

Whatever happened to "Fuel critical"??

I've used it once during a long hold when the airport was closed for the Thunderbirds. No paperwork.

-Matt

[peevee]

Min fuel means you can not accept any undue delay. You still wait your turn. 

 

Fuel emergency means you need priority handling and need to go to the airport now and land. Everyone else waits. 

[201er]

2 hours ago, cnoe said:

Have you ever had a gross error like this in the "wrong" direction? It sounds like there's a lot of room for improvement in your k-factor. I routinely see fuel consumption errors of less than ONE gallon when filling to capacity (64 gal. tanks). In your example the error was in excess of 10%! Could you have an old/bad fuel transducer? Or is it just not calibrated?

I'm trying to be helpful, not critical. Some of those high-tech fuel senders may be in order. If I eventually upgrade to a JPI (primary) monitor (900 series) I'd like to add them to my plane.

Mine takes 100 gallons. Actually it is hard to tell exactly how much it takes cause of the aftermarket tank expansion. Legally 98. Practically about 102. Depends how quickly you fill it cause it could go to maybe 104 if filled more slowly giving it time to fill all the tubes and spaces.

 

There are 4 caps. If a "top off" is off by half a gallon on each tank, that can add up to 2 gallons. Then there's expansion or sitting on a slanted ramp where some leaks out the vents. When you sump and dump, you lose a little each time. A lot of short flights vs one long flight will vary how much gets dumped. I have a small seep out the top of one of the tanks when full. How long it sits with that going on till the fuel gets below that level also effects it. If you don't top off for a long time and keep adding 10 or 20, errors add up as well. Dipstick measurements only get you to within a few gallons accuracy. And I have 4 tanks to dip. K factor calibration is only a part of the equation. Mine is probably within 0.2gph but that makes a bigger difference on a 90 gallon flight than a 40 gallon flight. Point is, the longer you go between top offs, the more gallons off your estimates may become.

[Bob - S50]

There is no set number for when you are minimum fuel or emergency fuel.  You have to set your own values.

Personally, I plan to arrive with at least 10 gallons.

If VFR, I agree with Turbo.  If I'm going to land with less than that, and there is someplace to stop along the way, stop and buy a little gas.

If IFR, if it appears that normal handling from ATC will cause me to land with less than the required reserve (45 minutes plus divert fuel if a factor) then I'll declare minimum fuel.  That would be likely touchdown with about 7 or 8 gallons if no alternate required.  I'm only going to declare emergency fuel if I need priority handling to get to the airport.  I'd probably do that if it appeared I'd get to the airport with less than about 5 gallons left.

My values might also change depending on the weather and proximity to potential divert airports.

Personal choice.

[Seth]

11 hours ago, 201er said:

Mine takes 100 gallons. Actually it is hard to tell exactly how much it takes cause of the aftermarket tank expansion. Legally 98. Practically about 102. Depends how quickly you fill it cause it could go to maybe 104 if filled more slowly giving it time to fill all the tubes and spaces.

 

There are 4 caps. If a "top off" is off by half a gallon on each tank, that can add up to 2 gallons. Then there's expansion or sitting on a slanted ramp where some leaks out the vents. When you sump and dump, you lose a little each time. A lot of short flights vs one long flight will vary how much gets dumped. I have a small seep out the top of one of the tanks when full. How long it sits with that going on till the fuel gets below that level also effects it. If you don't top off for a long time and keep adding 10 or 20, errors add up as well. Dipstick measurements only get you to within a few gallons accuracy. And I have 4 tanks to dip. K factor calibration is only a part of the equation. Mine is probably within 0.2gph but that makes a bigger difference on a 90 gallon flight than a 40 gallon flight. Point is, the longer you go between top offs, the more gallons off your estimates may become.

Mike-

My Missile is the same way.  I have the same Monroy STC expanded range tanks and my max fuel is 98 gallons.  I also have a small seep out of the top of the co-pilot side extended range tank.  After I burn odd a few gallons it's a non issue, but I rarely leave 98 on the ground.  A non flat filling surface, not letting all the cross feeding take place, or waiting extra time will vary the top load just as you mentioned.

I can get more than 98 in there if I'm really patient.

I'm very accurate with the two fuel totalizers on board (one required by the Missile upgrade and one a JPI 830), however I too act as if the  last 3 gallons don't exist. And use 95 as my max fuel for planning.  Though I add 98 for weight.

-Seth

[Danb]

I was taught not long ago at Flight Safety the difference in the way your handled by atc is based on the statements made, now if I can remember, if your low on fuel, not in an emergency situation you state that your getting into your reserves or something similiar and you would receive 'priority handling ' basically they limit delays or give you direct to; if you declare an emergency based on low fuel or worse; you are asked souls on board, remaining fuel etc. in this case it's direct to etc.

 

American Airlines during the fuel crisis a few years ago played with the rules requesting 'priority handling ' for many flights(100's) thereby getting many direct to situations in congested airspace saving tens of thousands until they were caught and fined.