airplane fuel quantity requirements

Factual Questions
1

In the thread on “what happens when an airplane is landing,” a link to this article was provided. In that article:

Years ago my dad (an ex-navy pilot and armchair aviation buff) told me that commercial planes were required by FAA regs to carry at least a particular quantity of fuel, and it went something like this:

-enough fuel to reach the planned destination, plus
-enough fuel for 90 minutes of hold time, plus
-enough fuel to reach the nearest alternate airport, plus
-an additional hour of hold time (the safety margin)

Not sure of the numbers/times there, but you get the idea: the FAA insists that planes have enough fuel to safely handle a variety of contingencies.

I have heard on previous occasions the complaint by the pilot in the article, i.e. airlines are pressuring them to fly with less fuel margin than they used to. I don’t understand this, because:

-it seems unlikely that the airlines would ever have encouraged/allowed planes to fly with much more fuel than needed, and
-it seems unlikely that the entire industry would ever dare pressure pilots to fly with less fuel than mandated by the FAA.

So what’s the deal:

-How much fuel really is required by the FAA for a commercial flight?

-Did commercial flights really used to fly with far more fuel than stipulated by FAA regs?

-Are airliners pressuring pilots to fly with illegally small quantities of fuel on board, or are they just pushing them to fly with exactly the amount required by regs?

2

FAA regulations state that a plane must take off with enough fuel to reach its destination, then to reach its most distant alternate airport, based on conditions, and then to fly at normal cruising speed for 45 minutes. Pilots argue that the FAA regulation does not recognize that modern aviation involves longer holding patterns that suck up the reserve fuel, and that pressuring them to reduce fuel costs to the FAA minimum presents a grave safety risk.

3

Are there rules that say how long they can fly a holding pattern before they’re required to divert to their alternate?

4

I don’t know. I’m an Australian pilot and although the aviation regulations worldwide tend to be similar in intent, they can vary in the specifics a bit.

In Australia we are not required to carry fuel for an alternate if the weather is fine at the destination. What we are required to carry is fuel for:

  • Taxi
  • Climb, cruise, approach and landing (collectively known as “flight fuel”)
  • 10% of the flight fuel to cater for contingencies enroute.
  • Plus any traffic holding requirements as published by NOTAM
  • Plus alternate and/or weather holding fuel as determined by the forecast for the destination.
  • Plus a final 30 minutes of fuel (calculated at the holding burn at 1500 feet.)

Yes. Maybe not “far more” but I think it was fairly typical to take a bit extra.

They’re being pressured to fly with the FAA minimums. It would be illegal to fly with less and any airline that suggested that wouldn’t be in business long.

The issue is that the captain has always had the final say on how much fuel should be carried on a particular flight and experience has shown that it is often wise to carry a bit extra “for mum and the kids” to cater for possible problems in flight. Increasingly the companies, in an attempt to save money, are questioning the decision to carry additional fuel. Captains dislike having their authority questioned for one and they particularly dislike people on the ground questioning decisions they make that they consider to be in the interests of the safety of the crew and passengers in the air. It’s a bit like what Americans refer to as the Monday morning quaterback. Additionally there is the perception that the company can punish a captain by giving them bad rosters. Whether or not this actually happens depends on the company but I think if the perception exists then the company has already failed to some extent in their obligation to back their captain’s reasonable operational decisions.

Referring back to the Australian requirements for sufficient fuel, you can see that it is essentially enough fuel to get to where you want to go plus a bit for enroute weather deviations or unexpected headwinds. The final 30 minutes of fuel must be in the tanks after landing and is non-negotiable never-to-be-used-in-anything-other-than-an-extreme-emergency fuel, the rest can be burned in flight.

There can be problems with the way fuel is calculated though. The fuel required to fly from A to B will typically be based on flying directly along the relevant airway, however during the departure and approach phase of the flight significant track miles, and therefore increased fuel burn, can occur due to radar vectoring and holding by ATC. On short sectors these additional miles may add a substantial percentage to the total miles flown and fuel used. That will eat into your contingency fuel. A company that is too focussed on fuel uplift might say “well, that’s what the contingency fuel is for” whereas the captain might say “but this happens every time we fly this sector so it is not contingency fuel at all but standard flight fuel that the flight planning software is not accounting for, I want to load additional fuel.”

On long sectors being forced by ATC to fly at a non-optimum cruise level can significantly increase fuel burn as can unforecast headwinds and lateral weather diversions (typically around lines of thunderstorms.) Where these things start becoming the norm it is no longer valid to say they are covered by contingency fuel, contingency fuel should be used by things that are abnormal and rare.

In the past companies wouldn’t question the fuel loaded by the captain, if the captain wanted an extra hour of fuel for mum and the kids then thats what they loaded. Now with the increasing competition among airlines and the continued pressure to keep airfares low, the companies are much more focussed on cost cutting. Companies are encouraging pilots to only take to the minimum legal fuel because heavy aeroplanes burn more fuel therefore it costs fuel to carry fuel, and apparently some don’t look kindly on pilots who continue to take additional fuel.

I’ve never experienced this kind of pressure myself but it is apparently out there.

I recently refused to do a flight because we could only load the absolute min fuel on the aeroplane and it was to a remote island out in the middle of the ocean (that is to say, with the aircraft fully loaded with fuel, we barely met the min requirements.) The ramifications of running short on fuel would’ve been a possible ditching with an associated loss of an aeroplane and maybe lives. This was not long after a medivac aircraft had ditched after encountering very poor (not forecast) weather at a remote island, and being unable to break through the cloud and land. The captain of that flight had been a Cleo “bachelor of the year” nominee. As I said to my first officer, “I’m too ugly to have my mug gracing the front page of every news paper in the country.” But to the credit of the company I work for, no one questioned my decision even though I could have quite legally flown the trip.

Not that I’m aware of. What you do is work out the minimum fuel required to fly from your destination to the alternate (lets call it “alternate fuel”). Normally you arrive at the destination with a bit more than the alternate fuel and if required to, you hold until you get down to the alternate fuel then you depart to the alternate. Normally you’d let ATC know that you only have say 10 minutes of holding before you need to divert then hopefully they’ll try and get you in somewhere. The problem is that the more aircraft there are carrying min fuel the more there are putting pressure on ATC to get them on the ground. ATC aren’t miracle workers, if they get one aircraft down early another aircraft will have been held for longer.

Edit: There is a complicating factor in the USA. The US have “dispatchers” who do the flight preparation on the ground and actually share a joint responsibility for the flight with the captain. As I understand it that responsibility even extends to when the aircraft is airborne. In Australia and other parts of the world the captain is the only person who is responsible for the flight in the air.

5

One final thing. I’m not sure how the FAA words their rules but the actual rule in Australia is that you shall ensure you have sufficient fuel for the flight, ie, THOU SHALT NOT RUN OUT OF FUEL! The requirements for fuel uplift that I gave in my post above are published by CASA (the Aus FAA) as an “acceptable means” of complying with the rule. A company will have its own operations manual that will spell out the company’s fuel policy. As the company’s ops manual is approved by CASA then the company fuel policy is essentially approved as an acceptable means of complying with the rule as well. The company’s fuel policy may be different to that specified by CASA and may in some circumstances result in a smaller fuel uplift but should result in an equivalent level of safety.

As an example, our company doesn’t fly passengers from A to B, we do aerial surveillance of the ocean for the Australian Government. We typically fly until we are at min fuel to get home and then we go home. This means that concepts like “flight fuel” are meaningless and we don’t carry 10% contingency fuel but instead have conservative fuel burn figures for planning our transit home and we plan to arrive overhead our destination with 15 minutes fuel on top of the 30 minutes required to land with. When we do a ferry flight direct from A to B we use the CASA fuel requirements.

6

It’s not a safety risk because there has always been a standard to be met. Airlines save money by flying with the correct fuel requirements needed for a given flight.

I think people get the impression that mileage and airports are treated as generic parameters and that is not correct. Schedules are set based on historic information so routes (read airports) with a history of delays will have scheduled times that reflect the realistic en-route time. The schedule will reflect block-to-block times and taxi time.

The scheduled flight time will be the base line from which additional time is added for weather or other factors (a radar center is down). The larger the system, the greater number of airports will be affected. Accordingly the more airports affected the greater the likelihood that a diversion airport will be pulled into the delay cycle due to diverted flights.

Pilots operate under the premise that there is no such thing as too long a runway, too much fuel, or too much thrust. When aviation fuel was 50 cents a gallon nobody cared if they hauled around extra fuel. But with today’s fuel costs it makes a big difference if every plane is carrying 1000 gallons of unnecessary fuel. Imagine every flight by a major carrier ties up $3,000 in dead weight. at 30,000 flights that’s 90 million dollars a day tied up in weight that could be traded for commercial freight.

7

The actual FAA regulations depend upon what the operating certificate of the aircraft is; most flights in the US operate under 14 CFR Part 121, but then the type of airplane and the operating conditions come into play.

14 CFR Part 121 can be found in its entirety here.
FAR 121.639:

FAR 121.641 - Fuel supply: Nonturbine and turbo-propeller-powered airplanes: Flag operations.

FAR 121.643 Fuel supply: Nonturbine and turbo-propeller-powered airplanes: Supplemental operations.

FAR 121.645: Fuel supply: Turbine-engine powered airplanes, other than turbo propeller: Flag and supplemental operations.

FAR 121.646 En-route fuel supply: flag and supplemental operations.

8

Just want to add that for very long haul flight, the idea of a redispatch in the air is sometimes used in US operations. Because the legal fuel requirement includes a percentage of the total flight time (121.645.b.2), when you have a very long sector, it may not be practical to carry enough fuel to satisfy all the requirements. You can work around that, however, by initially dispatching the flight legally to an airport short of the intended destination. Once you get much closer, if nothing unexpected happened and things are still looking good, then you redispatch the flight in the air to the real destination. I know the United O’Hare to Hong Kong non-stop uses this technique, for example.

9

The only time you have too much fuel is when you are on fire.

10

We sometimes do this as well when operating to one of our remote island destinations. We actually dispatch for the remote island itself but re calculate fuel prior to our point of no return to the enroute alternate, if we have enough fuel at that point we continue, if not we divert.

11

Former US commercial big jet driver. …

Richard Pearse’s first post perfectly captures the situation.

No airline that wants to stay in business runs below the letter of the law. But there are elements of wishful thinking in some carrier’s planning some times.

The classic case is the traffic delay that occurs on 90% of the attempts of a particular flight from A to B, yet is still accounted for as “unexpected” in the planned flight time & burn calculations.

Macgiver’s assertion that this is *always *accounted for accurately and truthfully is wishful thinking. Often it is; sometimes it isn’t.

A professional pilot (one who acts like a pro, not just one who earns a paycheck flying ), is aware of both the need for safety & for profitability through avoiding waste. There may have been a time where pilots’ attitudes was always take teh longest runway, always take extra fuel, etc. In the professional cultures I’ve been involved with, this simply isn’t done. The pilot and dispatcher work together to determine what this individual flight really needs on this particular day. Sometimes that’s a bit more than the computer programmed with management;s assumptions thinks. Usually the computer is right. But not always.
The challenge with fuel scrimping, as with maintenance scrimping, is that it’ll work fine for lots and lots of flights on lots and lots of days. And then one day it won’t for one flight. And when that happens, all the savings will be spent on the lawsuits & buying a replacement jet.

And the people who pay the real price with their lives won’t be the people who saved the money.

The NASA Challenger mishap occured because over the years safety margins were slowly eroded. What had been *outre *became normal. There is some legitimate concern that the total safety level of the US air system is likewise being erorded through long term underinvestment and short term cost cutting.

Having a buttload of big jets converging on a hub, each with enough fuel to do the job if everything unfolds as expected, can get messy when the airport suddenly closes and everybody needs to go someplace else right now. Suddenly everybody is real marginal on fuel and a bunch of nearby (in jet terms = ~200 miles) otherwise sleepy airports are about to receive a horde of jets that need to land right now.

IMO insufficient attention is paid to the systemic effect of a mass divert scenario. Each flight is fuel planned as if it would be the only one in the sky needing to divert. Yes, it’s fuel plan covers the expected effect of normal traffic going to the hub, plus that one flight needing to go someplace unexpected. But just like theaters need extra emergency exit doors for the rare occasion where *everybody *needs to leave now, we ought to have that consideration built into airline flight planning. Which won’t happen until / unless it is required by regulation.