Fuel Reserves

[Bill Bridges]

I found this interesting article on fuel reserve definitions. From the article it appears that the FAA doesn't care what fuel the aircraft lands with, just that it was legal when it left? Is minimum fuel at destination more of a company policy. One of the question I have, and maybe Larry or one of the other 121 guys is what number do you place in the FMC on the PERF INT Page for Reserves?

[Larry sreyoB]

All the reserves in PERF INT does is give you a scratchpad message when your arrival fuel is projected to be below reserves.

I put the minimum legal reserve amount in PERF INIT during preflight. Many Captains increase that somewhat so that they'll get an earlier alert.

[Ray Tackett]

it appears that the FAA doesn't care what fuel the aircraft lands with, just that it was legal when it left?

Reserves are there to be used, if necessary. A missed approach followed by diversion to another airport is one example. I know of one case where a former student had to do an improvised diversion from his alternate. That is exactly what IFR's alternate plus 45 minutes is about.

OTOH, aircraft rental outfits, e.g. flight schools, do care what you landed with, especially on no-problem VMC days. Running low on fuel for no apparent reason is troubling.

[Scott Dyer HPN/NY]

From the article it appears that the FAA doesn't care what fuel the aircraft lands with, just that it was legal when it left?

Bill -- I wouldn't draw such a broad conclusion. 91.167 states, in pertinent part:
§91.167 Fuel requirements for flight in IFR conditions.

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

(b) Paragraph (a)(2) of this section does not apply if:

(1) Part 97 of this chapter prescribes a standard instrument approach procedure to, or a special instrument approach procedure has been issued by the Administrator to the operator for, the first airport of intended landing; and

(2) Appropriate weather reports or weather forecasts, or a combination of them, indicate the following:

(i) For aircraft other than helicopters. For at least 1 hour before and for 1 hour after the estimated time of arrival, the ceiling will be at least 2,000 feet above the airport elevation and the visibility will be at least 3 statute miles.


Compare to the prefatory language of the VFR regulation, 91.51:
§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.


From that, we see that continued operation of an aircraft under IFR in instrument conditions, without the required alternate fuel, violates 91.167 while continued operation of an aircraft under VFR does not so long as the VFR flight began with the requisite fuel on board.

Now, what if during the flight the IFR flight planned destination forecast becomes such that the alternate fuel requirements are no longer required? In that case, the IFR flight may proceed without the reserve fuel that may have been required by regulation at departure. See the 2005 chief counsel opinion in Gallagher, https://www.faa.gov/about/office_org...rpretation.pdf

Thus, there may be weather changes enroute that will permit an IFR flight to land at the destination with less than the reserve fuel that may have been required on takeoff, but the converse is also true: changes in weather forecasts or reports while enroute may subject a flight under IFR to have the 91.167 reserve fuel on board when that reserve fuel may not have been required at departure.

Here's a fun fact that I wasn't aware of until recently, too....differences in fuel density around the world can "cheat" a G-V aircraft out of several hours of flight time despite "topping off". See http://code7700.com/fuel_minimums.htm

[Richard Duxbury]

Sigh, brings back memories of flying that old fuel greedy B-747-200 to Narita. Back then they only had one runway. We would get nervous if we looked at less than 30,000 lbs in the approach. Dirty and low it could use 20,000-25,000 lbs an hour. Additionally we did not trust the fuel guages. (circa 1990). Well now newer more efficient aircraft-more runways, honest fuel indications, etc.

Then I retired and flew a local rented (FCM) Beach Sport. I think we (well, sometimes solo) would have full wing tanks of 2X25, which was good for almost 4 hours. Even then (worse now) I had a 2 hour pee limit, thus never worried about enough fuel when I returned. (circa 1997-2000).

Regards, no flying now except as a passenger.

Dux

[Randy Sohn]

Sigh, brings back memoriesx

Boy-oh-boy, do I ever remember! Read it all and "it's nice to be retired!"

best, randy

[Tom Charlton]

From the article it appears that the FAA doesn't care what fuel the aircraft lands with, just that it was legal when it left? Is minimum fuel at destination more of a company policy.

Hi Bill and others,

Interesting topic.
Forty one years in the world of Aerial Mapping. More often than not we’d depart with full tanks but no specific destination other than the project site. Typically projects required more than one flight to complete. Just fly until you’re out’a gas! Don’t know which end of a multi-line, fifty mile long project that you’ll be low on fuel. Can I get this one more flight line done or do we drop in to Opa Locka Airport here at the south end of the project now. All projects had a multitude of required conditions such as sun angle, no clouds or cloud shadows or ocean tidal constraints. Lot’a self-induced pressure to get just one more flight line flown. Remembering once or thrice mentioning to tower: ahhh . . . minimum fuel.

FAA fuel reserve rules just didn’t apply/work. My policy for my flight crews was to end up on final approach, somewhere, with at least an hour on board. Was always an interesting / challenging juggling act.

Regards,
Tom Charlton (Yup . . . tiz good to be retired<g>)

[Dave Siciliano]

I may technically violate those IFR regs when I make long flights. For instance, I recently planned from Greenville, SC to Addsion, Texas and it showed the flight would take about all fuel on board. I planned to Addison, but had to airports short of that where I would check fuel and stop if needed. If I planned to the other airports, I'd get different routing and couldn't consider enroute conditions and changes along the way. It was projected IFR with low ceilings at Addison, but 75 miles east along my route, it was higher ceilings or VFR. So, I had two go/no-go points at Alexandra and Longview. Turned out, I stopped at Longview and got some fuel, but conditions could have changed and made it fine to continue to Addison. It's been pointed out, I didn't comply technically. If something happened, that could have been an issue. The legal alternative would have been to plan to Alexandria or Longview and amend the plan enroute. Seems to me, some common sense should apply. I logged fuel used, remaining and ETA hourly. Knew exactly where I stood as fuel got low, but I see why they have the rule.

[Bill Bridges]

Knew exactly where I stood as fuel got low, but I see why they have the rule.

We're (or at least I am) getting way too old to be going 10 minutes into a 20-minute light. ROFL

[Randy Sohn]

fuel greedy B-747-200 to Narita

And not only Narits (Tokyo), Seoul and Australia and some other places on the other side of the world. Re-releasing and all that other good stuff. Takes w-a-y more typing that I really wanna get into here, Larry or some current 121 guy?

best, randy

[Dave Siciliano]

We're (or at least I am) getting way too old to be going 10 minutes into a 20-minute light. ROFL

Exactly my point. Just having the fuel to meet criteria when leaving may be very different than what happens enroute. I judiciously check enroute. Pull up if need be, but have had circumstances improve and gone on.

[Dave Siciliano]

Rules by that towering regulatory org :-)

[Bruce Gorrell]

Bill -- I wouldn't draw such a broad conclusion. 91.167 states, in pertinent part:
§91.167 Fuel requirements for flight in IFR conditions.

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

(b) Paragraph (a)(2) of this section does not apply if:

(1) Part 97 of this chapter prescribes a standard instrument approach procedure to, or a special instrument approach procedure has been issued by the Administrator to the operator for, the first airport of intended landing; and

(2) Appropriate weather reports or weather forecasts, or a combination of them, indicate the following:

(i) For aircraft other than helicopters. For at least 1 hour before and for 1 hour after the estimated time of arrival, the ceiling will be at least 2,000 feet above the airport elevation and the visibility will be at least 3 statute miles.


Compare to the prefatory language of the VFR regulation, 91.51:
§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.


From that, we see that continued operation of an aircraft under IFR in instrument conditions, without the required alternate fuel, violates 91.167 while continued operation of an aircraft under VFR does not so long as the VFR flight began with the requisite fuel on board.

Now, what if during the flight the IFR flight planned destination forecast becomes such that the alternate fuel requirements are no longer required? In that case, the IFR flight may proceed without the reserve fuel that may have been required by regulation at departure. See the 2005 chief counsel opinion in Gallagher, https://www.faa.gov/about/office_org...rpretation.pdf

Thus, there may be weather changes enroute that will permit an IFR flight to land at the destination with less than the reserve fuel that may have been required on takeoff, but the converse is also true: changes in weather forecasts or reports while enroute may subject a flight under IFR to have the 91.167 reserve fuel on board when that reserve fuel may not have been required at departure.

Here's a fun fact that I wasn't aware of until recently, too....differences in fuel density around the world can "cheat" a G-V aircraft out of several hours of flight time despite "topping off". See http://code7700.com/fuel_minimums.htm

None of that says anything about how much fuel you have to have on landing, only how much fuel you have to have to take off.

[Scott Dyer HPN/NY]

Bruce, 91.167 is a requirement for "operating", not taking off. 91.151 speaks to when you "begin" a VFR flight. I hope that I'm "operating" the aircraft when I'm landing it. ;-)

[Randy Sohn]

requirement for "operating",

Head shakin' mode here, makes me go w-a-y back to think about what we always said - "when you set your parking brakes at the destination's gate and the fuel gauges all settle down on the totalizer, better show XX minutes" (was XX 45 minutes?)

And I'd better add this so that someone doesn't get it wrong, the totalizer read pounds, not minutes. It was up to the gauge's reader to interpret it as to time and it DIDN'T read at what altitude.

best, randy