FLYING LESSONS for December 19, 2024

Topics this week include: > The real answer > We’ve got to do better > Hypervigilance

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FLYING LESSONS uses recent mishap reports to consider what might have contributed to accidents, so you can make better decisions if you face similar circumstances.  In most cases design characteristics of a specific airplane have little direct bearing on the possible causes of aircraft accidents—but knowing how your airplane’s systems respond can make the difference in your success as the scenario unfolds. So apply these FLYING LESSONS to the specific airplane you fly.  Verify all technical information before applying it to your aircraft or operation, with manufacturers’ data and recommendations taking precedence.  You are pilot in command and are ultimately responsible for the decisions you make.     

FLYING LESSONS is an independent product of MASTERY FLIGHT TRAINING, INC.

This week’s LESSONS:

A Piper Navajo was conducting an aerial survey flight that lasted over five hours before the pilot began his return to home base. The big twin ran out of fuel, the pilot dead-sticked into a busy highway, and the Piper collided with cars and obstructions, breaking the fuselage apart. AVweb reports:

While on a night approach the pilot of a Cessna 340 encountered engine problems near the end of a five-hour flight. According to preliminary reports the pressurized twin:

My friends at General Aviation News recently published this account of a Pipistrel Virus SW fuel exhaustion accident:

How much fuel does your airplane burn? If you’re like most pilots you’ll answer with the cruise fuel flow. “My airplane burns 12 gallons per hour,” for example. But what about fuel for takeoff and climb? The airplanes I most commonly fly—various models of later Beech Bonanzas with 285 to 300 horsepower engines—burn between 12 and 14 gallons per hour in the 7000 to 9000 Mean Sea Level (MSL) range if leaned for best fuel specifics (most horsepower for unit of fuel burned). But takeoff and climb from my home airport at about 1400 MSL and I’ll go through a quarter tank of fuel—close to 10 gallons—in the time it takes to reach cruising altitude. If I stay lower, say 4000 to 6000 MSL, it takes less fuel to climb but the cruise fuel flow increases.

What is your airplane’s range? Most pilots will have an answer to that question. But range—the distance an airplane can travel—is variable based on power setting, itself a function of mixture management technique, Range is wildly dependent on winds…a factor almost completely out of our control. For a given power setting an airplane has a theoretical range in zero winds, but since that’s virtually impossible the idea of a fixed range is not really usable for flight planning.

What is your airplane’s endurance? That’s the real answer to know. An airplane will fly a certain amount of time before it runs out of fuel. That time still varies depending on fuel load at takeoff, selected power setting, altitude, time to climb, and more.

Because there are so many variables, it’s critical that you know the fuel level at takeoff, the expected fuel burn for climb and cruise fuel flow, as well as fuel required for descent, approach and even missed approach or go-around, re-climb to altitude, and cruise to and approach and landing at an alternate airport. Add to that, at a minimum, the regulatory endurance (30 minutes for day VFR under U.S. rules; 45 minimums for IFR or night VFR). I use one hour remaining as my minimum.

Further, you must monitor fuel flow in flight to confirm your planning remains valid and to detect any condition where fuel use is not meeting preplanned expectations. This includes scanning behind fuel caps and along the trailing edge of the wings for any sign of fuel leaks or overflows that are not detectable by fuel transducers and engine monitors. Fuel siphoning and venting scenarios may even cause an erroneously high fuel quantity indication in some types of aircraft. 

If you think aircraft fuel gauges are “notoriously inaccurate” and “only need to read accurately when the tank is empty,” then you have not read the regulatory requirements for fuel gauge accuracy across the full range of indications. Among many other things, 14 CFR 23.2430(a)(4) requires aircraft fuel systems to “Provide the flightcrew with a means to determine the total useable fuel available….” Not just when the tanks are empty, or when they are full, but the total usable fuel available at any time. Fuel quantity gauges are inaccurate only if the aircraft owner has not maintained them properly.

It’s even more important to have a plan for managing your fuel system in flight, and to follow your plan once airborne. Fuel starvation—when there’s usable fuel on the airplane but it is not getting to the engine(s)—is more common in accident reports than fuel exhaustion, running completely out of fuel. Although it seems reasonable to assume an engine will restart immediately if a tank runs dry and the pilot switches to a tank that contains fuel, the record shows this doesn’t always work…a lot. Follow a planuse a timer or reminder to prompt fuel tank selection, and switch tanks before the tank runs completely dry to avoid the single most common cause of engine failure accidents.

Put all the variables together and, with some notable exceptions, most light airplanes seem to have about five hours of fuel on board when filled to maximum capacity and with the engine and fuel tank system managed properly. If the total time since the last top-off has been more than four hours you probably have less than an hour’s fuel remaining. Although regulations permit taking off with as little as half an hour of fuel expected to be remaining when you land, that’s only for planning purposes and many pilots adjust their flight to land before they have only an hour of fuel remaining on board based on calculations updated as a flight progresses. 

Some countries require at least the minimum fuel reserve to actually be in the tanks at the end of a flight. Burn any of your reserves and you’ve violated those justifications’ regulations.

Regardless, if you take off with full tanks and your airplane has about five hours of fuel on board, land before you reach four hours aloft…even if you have to land somewhere inconvenient, fuel up regardless of price, and then only fly a short distance to your original destination. If you depart with less than full tanks, or have a fuel tank system that provides for greater endurance, adjust that time accordingly. 

Any flight planned to within an hour of the endurance resulting from fuel load at takeoff, climb, cruise, descent, approach, go-around/missed approach, climb, diversion and landing with no less than regulatory fuel reserves plus any personal minimum is a science experiment. It may turn out the way you expect, if you monitor closely and manage all the variables correctly. But it’s equally possible you’ll get a different outcome that requires landing for more fuel before you burn into that reserve.

I was an Account Executive selling aircraft insurance in AOPA’s insurance company in the mid-1990s. When taking applications for insurance we asked all the standard questions, including whether the applicant had any accident or aircraft insurance claims experience in the previous five years. But our underwriters had us ask if a pilot had ever had a fuel starvation or fuel exhaustion accident or insurance claim. Fuel mismanagement was “the unforgivable sin” that made a pilot essentially uninsurable for the rest of their life. 

Justified, fair or not, way too many accidents result from fuel mismanagement. AOPA’s Air Safety Institute reviews of NTSB reports indicate as much as 90% of all NTSB-investigated engine failure accidents are the result of the pilot’s operation of the fuel system. And the recently released 2024 Richard G. McSpadden Report shows that the trend in fuel mismanagement accidents is showing a decade-long increase, nearly doubling over the past 10 reporting years.

Fuel-related accidents 2013-2022 (2024 McSpadden Report)

We’ve got to do better…and if we do, we can prevent the vast majority of engine failure accidents. 

Questions? Comments? Supportable opinions? Let us know at [email protected]

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Debrief

Readers write about previous LESSONS

New reader Brad Wolanski, who regularly flies a Piper Seneca between Lakeland, Florida and the Bahamas, has “recently created a type specific group for the Seneca because none previously existed” at www.pa34owners.org and https://forums.pa34owners.com. Brad “hope[s] to include topics and stimulate discussion about flying the Seneca safely. And in particular, of course, responding to its emergencies.” Seneca pilots, instructors and enthusiasts, check it out. 

Frequent Debriefer John Scherer writes about the LESSONS I learned from attending the 2024 Bombardier Safety Standdown:

The “70/50 rule,” that is, the airplane should be at 70% of its computed liftoff speed at 50% of its computed takeoff ground roll under current conditions, is a common way of confirming whether air airplane is accelerating properly or the pilot should immediately perform a rejected takeoff (RTO). 

John continues:

N1 is the rotational speed of a jet engine’s low-pressure spool, which is made up of the fan, low-pressure compressor, and low-pressure turbine. N1 is usually displayed as a percentage of the engine’s maximum rotational speed (RPM). N1 is a primary indicator of engine thrust on many jet engines. John continues further:

 

Thanks for a great peek into the world of super-heavy airplane operations, John, and how that experience applies to flying light airplanes.  

Reader Vas Ketavarapu adds to last week’s Debrief on the availability of Minimum Vector Altitude (MVA) and Minimum IFR Altitude (MIA) information, useful in making instrument departures from nontowered airports and also when planning to depart under Visual Flight Rules and “pick up” an IFR clearance in the air:

Great information, Vas. Thank you.

More to say? Let us learn from you, at [email protected]

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And thanks to these donors in 2024:


Thomas P. Turner, M.S. Aviation Safety 

Flight Instructor Hall of Fame Inductee

2021 Jack Eggspuehler Service Award winner

2010 National FAA Safety Team Representative of the Year 

2008 FAA Central Region CFI of the Year

FLYING LESSONS is ©2024 Mastery Flight Training, Inc.  For more information see www.thomaspturner.com. For reprint permission or other questions contact [email protected].  

Disclaimer

FLYING LESSONS uses recent mishap reports to consider what might have contributed to accidents, so you can make better decisions if you face similar circumstances. In most cases design characteristics of a specific airplane have little direct bearing on the possible causes of aircraft accidents—but knowing how your airplane’s systems respond can make the difference in your success as the scenario unfolds. Apply these FLYING LESSONS to the specific airplane you fly.

Verify all technical information before applying it to your aircraft or operation, with manufacturers’ data and recommendations taking precedence. You are pilot in command, and are ultimately responsible for the decisions you make.