Here's a question that sounds simple: you're flying 400 NM in your Skylane. Should you cruise at 55% power to save fuel, or 75% to get there faster?
Most pilots assume economy cruise is always cheaper. Less fuel per hour, lower cost, right? Not necessarily. When you factor in your overhaul reserve, prop reserve, and maintenance — all of which tick by the Hobbs hour — flying slower can actually cost more per mile than flying faster.
Two Costs, One Hobbs
Your cost per nautical mile has two components:
Fuel Cost per NM
(GPH × Fuel Price) ÷ TAS
Rises with power. More GPH, but TAS doesn't rise proportionally. At $7/gal in a 182: 55% = $0.52/NM, 75% = $0.63/NM.
Dry Cost per NM
Dry Rate ÷ TAS
Falls with power. Same $/hr, but spread over more NM at higher TAS. In a 182 at $35/hr dry: 55% = $0.30/NM, 75% = $0.25/NM.
The question is: does the fuel cost increase outweigh the dry cost decrease? That depends on your fuel price, your dry rate, and your aircraft's TAS/GPH curve. There's no universal answer — but there is a calculator that finds yours.
A 400 NM Trip in a Skylane
C182, $6.50/gal, $35/hr dry rate (engine + prop reserves + maintenance):
| Power | TAS | Time | Fuel $ | Dry $ | Total | $/NM |
|---|---|---|---|---|---|---|
| 55% | 118 kts | 3h 23m | $209.32 | $118.64 | $327.97 | $0.82 |
| 65% | 130 kts | 3h 5m | $230.00 | $107.69 | $337.69 | $0.84 |
| 75% | 140 kts | 2h 51m | $250.71 | $100.00 | $350.71 | $0.88 |
In this case, 55% is cheapest per mile — the fuel savings outweigh the extra Hobbs time. But change the fuel price or dry rate and the answer shifts.
When Does Higher Power Win?
The crossover happens when your dry rate is high relative to your fuel cost. Aircraft with expensive overhauls (turbocharged engines, complex constant-speed props), high maintenance rates, or low TBOs push the $/NM optimum toward higher power. Cheap fuel does the same — if avgas drops to $5/gal, the fuel component shrinks and dry costs dominate.
For flight schools with time-based costs like aircraft payments, 100-hour inspections, and insurance amortized per Hobbs hour, the fixed hourly burden is even higher — making the case for higher cruise power on XC legs even stronger. See our Fleet Economics Calculator →
The Time vs. Money Question
Even when economy cruise is cheapest per mile, there's a tradeoff: time. On that 400 NM trip, 55% gets you there in 3:23. 75% gets you there in 2:51 — 32 minutes sooner. The extra cost? About $23.
That works out to roughly $43/hr for the time you buy back. Is 32 minutes of your life worth $23? Only you can answer that. But the calculator shows you the exact number for your airplane and your trip so you can make the call with data instead of a guess.
Find Your Number
Enter your aircraft, your fuel price, your operating costs, and your trip distance. The calculator finds the power setting that minimizes your cost per nautical mile — and shows you exactly what the time tradeoff costs.
Blue skies and tailwinds.
— Kauai Mansur, Pilot & Founder, VectoredOps
Disclaimer: This article and calculator are for informational purposes only. Results depend on your inputs and should be verified against your POH and maintenance records. Performance varies with altitude, temperature, weight, and configuration. The author is not a certificated flight instructor. VectoredOps Inc. is not liable for decisions made based on this content.