Things don’t always go as planned – a universal truth in life and readily apparent in aviation. I experienced this first-hand on a recent return flight to my home base at the Clermont County Airport. Storms were quickly building from the west at my departure airport as expected. While the impact to my route appeared minimal, the domino effect on arriving and departing traffic from this busy reliever airport in a major metropolitan area wreaked havoc on everyone’s schedule this summer afternoon – no matter the route of flight.
It started innocently enough with a quick IFR clearance for our filed route and no mention of delays on the ATIS frequency or from Clearance Delivery. It was a short taxi from FBO parking to an intersection for departure when we began to hear the chatter on ground frequency with references (concerns) to the length of time some aircraft had been waiting for departure. Reports ranged from 30 minutes to as much as an hour.
No time to panic. Relatively speaking, when things don’t go as planned in aviation, the best time to consider alternatives is while still on the ground while only a short taxi back to the FBO with cold drinks, soft couches, and WiFi as was the case in this situation. The discipline is in not allowing a minor ground inconvenience manifest into a dire inflight emergency by not considering all of the potential ramifications. On this particular flight, these additional considerations included more fuel consumption, passenger comfort, developing weather, and night fall.
At top of mind, and complicating the contingency plan, was an unknown departure time and resulting additional fuel usage. A close second was passenger comfort on a sweltering summer afternoon. Even air conditioning wasn’t able to keep up with a crowded cabin.
Given the busy terminal airspace and summertime potential for slight weather deviations, we had opted for extra fuel above and beyond normal reserve. This would be the reserve fuel I’d be willing to tap in the case that our departure delay drug along. I was not willing to tap into my planned one-hour inflight fuel reserve to be used strictly for unforeseen, inflight circumstances. Again, the minor inconvenience of taxiing back to the FBO for additional fuel is certainly not worth inducing an inflight emergency further down the line.
With fuel load under control at the moment, I turned my attention to passenger comfort. This was a hot summer day in the south. With a moderate number of passengers in a relatively small cabin, air conditioning was making the environment tolerable, but not cool by any means. After conferring with the passengers and offering to return to the FBO should conditions warrant, we opted to remain in line.
Turning our attention back to fuel, I began to consider potential fuel savings measures that could be taken en route when we did receive the much-anticipated takeoff clearance. Reduced power and/or higher altitudes are both relatively simple steps that can have substantial impact if the flight conditions (terrain, weather, airspace) allow.
Take a Cessna 172 for example. For the same power setting, simply going from 4,000’ MSL to 8,000’ MSL can provide a fuel savings of about 10% (nearly a gallon per hour) with essentially no drop in true airspeed. Just a 2,000’ climb at the same power setting will deliver a 5% fuel savings and no sacrifice in true airspeed. More direct routing was also under consideration, but given that we’d be flying IFR, this is a factor we’d save as a bonus given the many variables and airspace congestion that could prevent a more favorable route.
After several updates from ATC (some requested, some not), we were off at essentially our pre-determined minimum fuel quantity. For me, this was calculated at flight planned fuel plus one-hour reserve for unforeseen delays or emergencies enroute. We’d been able to monitor weather while still on the ground offering confidence weather would not impact the return trip or add flight time and fuel.
In terms of more favorable direct routing, it wasn’t in the cards this particular day. To add insult to injury, ATC instructed a descent to a lower altitude (and higher fuel burn) earlier than anticipated. While enroute, we did opt for a lower power setting to conserve fuel which sacrificed some speed, but provided enough net benefit, that it negated the additional fuel consumed at the lower altitude.
An important point to be made concerning your interaction with ATC in regards to fuel. Fuel concerns or emergencies should never be taken lightly and require clear communication so that everyone involved understands the circumstances. The Aeronautical Information Manual (AIM) provides for a minimum fuel advisory as a first indication that fuel quantity is a concern.
A fuel advisory is NOT an emergency (and many emergencies have resulted because of this misunderstanding), but indicates that your fuel has reached a state where, upon reaching your destination, you cannot accept any undue delay. The term “minimum fuel” should be used when providing a fuel advisory to ATC.
If your fuel status reaches a critical level, a fuel EMERGENCY should be declared. This will ensure traffic priority and the full complement of resources available from ATC to help effect a safe outcome. While a fuel emergency often can be traced to poor planning, don’t allow prior mistakes to be compounded by delaying adequate assistance and landing priority.
As we approached our final destination and home base, we were greeted with a serene sunset, calm winds and clear skies drawing a happy conclusion to a long, frustrating day. While the FBO had closed for the evening, there was plenty of light and plenty of help to secure the airplane and usher the passengers to their cars and the eventual treasure of making it home to their own beds (the magic of general aviation).
For the best-laid plans of mice and men often go awry, on this particular flight, we considered:
- Fuel load and consumption
- Passenger comfort
And the benefits of general aviation!