Mind Your Fuel Status, Part 1
“The more things change, the more they remain the same.”--Jean Baptiste Alphonse Karr
Benet Hanley took Karr’s statement to mean “Turbulent changes do not affect reality on a deeper level other than to cement the status quo. A change of heart must accompany experience before lasting change occurs.”
I thought that explanation appropriate when reading about the following two incidents. You will note two very similar “turbulent” moments in them. We can bet that after the first there was some change of heart, but it still happened again--50 years later. I leave out official findings because there are none available in the second incident, and, in both cases, I think the impact is stronger when the readers put themselves in that position and think about what they’d do.
Each time the last gear door shuts and the flaps come up, the clock starts on a finite amount of fuel that is available to keep the show running. No one has completed a professional career without the experience of watching fuel levels decrease while facing choices about where to land. Those experiences can range from mildly annoying to all-encompassing.
Fuel planning has come a long way in the last 50 years.
After active duty in fighters, I started out flying a Gulfstream GII for the American Can Co. out of Westchester County Airport (KHPN) in New York. My two “tutors” were both highly experienced heavy twin-engine pilots going back to DC-3s, C-46s and Convair 440s.
Fuel planning in the early 1970s went something like this:
“Pick your distances off the IFR chart, divide by your ground speed. Use 400 kt. westbound and 450 kt. eastbound from takeoff to landing. Figure 5,000 lb. the first hour and 3,000 every hour after that. Write all the figures down and, as you go along, compare how you’re doing with what you planned. If there’s weather, figure 200 kt. to your alternate and another 2,500 for the missed approach and travel if it’s one of our normal alternates.”
It worked, for the most part.
Most of the jets that I flew later in my career were usually capable of flying very long ranges. When considering a short trip (less than 6 hr.) I seldom worried about having enough fuel. I could carry what I needed and still have plenty of reserves for whatever could be planned, but when I was all done, and it was time to order the fuel, there was always one more consideration: “What if?” How much, if any, for the unknown unknown, were there to be one.
Fuel planning became more and more sophisticated. Computer flight plans started to appear in the early 1980s. The fuel-used portions were determined on basically the same algorithms as the manually generated procedures mentioned above, but they were improving.
However, no matter how accurate and how perfect it became, there was always the “what if” for consideration.
About halfway through my career, while flying C-5s part time in the Air National Guard, the Airlift Command was only slightly more advanced than when I started. You would receive a computer flight plan but still had to manually confirm how much JP4 to upload.
On a weekend “Guardsman trip,” we were carrying Navy cargo out of Chambers Field in Norfolk, Virginia, bound for Rota, Spain. We checked with the loadmasters as we walked into base ops and they gave us the cargo load: slightly heavier than the customary 130,000 lb. to Europe as I recall.
Fuel planning then was done with big books containing charts that were well-worn and pencil-marked at the 130,000-lb. cargo and 7 hr. of flight lines. But on this particular night, due to winds and that slightly heavier-than-normal load, we couldn’t get enough fuel on board to get out of Chambers’ relatively short runway (8,300 ft.), clear the required ships (you had to consider the height of the ships in certain docks off the end of the runway) and still make Rota. Try as we might, the results didn’t give us enough fuel at the maximum weight to get over the obstacles and still have the required fuel for Rota and reserves for the Torrejon alternate. We’d have to download cargo.
Then one of the guys had a great idea. “Let’s take XXXXX lb. less fuel. [It was 30 years ago--I forget the number.] That gets us right to FL330 instead of FL290 and the amount of fuel we’ll burn for that time leaves us enough.
I’ll be darned. It worked.
Fuel planning continued to improve. The effects of altitude, speed and even configuration are now figured into fuel burns. Computer flight plans and modern FMS computers show you the amount of fuel you’ll have at landing within a percentage point and the time often within a minute, given no “what-ifs.”
In his 2014 book, Air Disaster 2: The Jet Age, Macarthur Job discusses the plight of a crew flying an almost-brand-new DC-9-32 for Overseas National Airlines (ONA) in 1970. I’m not trying to dig up a dead body by going back so far, but as I was reading the book, I was struck by the similarity of this event to a modern-day scenario where the crew almost “came a cropper” for the exact same reasons.
In the 1970 incident, the flight was scheduled from JFK International Airport (KJFK) to Princess Juliana International Airport (TNCM) in St. Maarten. The crew had completed all their required flight planning--much the same, probably, as we did in in a corporate GII--loaded 57 passengers and 29,000 lb. of fuel, filed and headed for St. Maarten. The weather had been dutifully checked and showed that there would be scattered thunderstorms all the way from JFK to the destination and that St. Maarten would have a southeast wind at 10 kt., with scattered clouds at 2,500 ft. and a chance of thunderstorms.
That reminds me of a friend who, when asked what he thought the weather would be for an upcoming trip to San Juan, replied, “Just what it always is, wind out of the east at 9-10 kt., 2,000 scattered--or a hurricane.”
Well, on the day that the DC-9 headed south there was little chance of a hurricane, but thunderstorms were predicted to lower the visibility as low as 2-5 mi. and have a base of 500 ft. Still, not too terrifying per se but just a shadow on the horizon of the flight planning.
Approximately 200 mi. north of the destination, San Juan control advised the crew that the weather at St. Maarten had gone below minimums for the approaches available. The captain had filed St. Thomas as an alternate but wisely, at that position, decided to divert to San Juan. It would be just about the same distance as St. Maarten, so the flight was still well within the plan.
The captain didn’t have the luxury of seeing how each plan change would affect his arrival fuel. Nevertheless, the divert to San Juan was a distance that would require a fuel load less than going to St. Maarten and then to St. Thomas, so it was a good decision. Less fuel needed, better airport. The turn was made, and the flight proceeded for a short time.
“Sir, the weather at St. Maarten has just come up to better than minimums.”
Then the train started to come off the tracks.
Instantly, the pilot was put in a situation where a seemingly reasonable decision to go back to the original plan of landing at St. Maarten put him without having an accurate idea of how the fuel used in the brief diversion toward San Juan might have affected his overall fuel state.
In Part 2, we’ll discuss the outcome of this flight and investigate a similar situation 50 years later.