X-c delayed

Tomorrow they're calling for high winds and some areas along the x-c route will be gusty. So we're pushing the trip back to Tuesday afternoon.

Tonight I did the route (which may change; waiting on info from Chuck) on a nav log worksheet I found here. The route was JGG -> RIC -> RZZ -> ECG -> JGG.

After much swearing and irritation, I got everything done with the "analog" E6B. Part of it really, really didn't make sense -- like when trying to determine how long it takes to climb to 3500' from sea level at a climb rate of 840'/min. My brain quickly estimates that to be in the neighborhood of 3.5-4 minutes. The E6B, when read according to its instructions, tells me 2.1 mins. (If, however, I look at the hours scale instead of the minutes scale, it shows ~3:35, which jives with the mental math.)

In any case, I brute-forced my way through it (no wind corrections) and found that it would take 2:30 for 239 nm and we'd use ~18.5 of the 38 gallons of fuel. I calculated the time and distance for the climb-out portion of each leg, and used the remaining leg distance for calculations at best cruise performance. I did not deduct anything for lower fuel consumption on descent, figuring that could be some built-in buffer. I also used different burn rates for different altitudes, as specified by the POH.

AOPA RTFP came up with similar but different numbers. It says 2:22 for 239 nm with 17 gallons of fuel.

I learned two main things from the comparison between the by-hand method and using the RTFP. First, RTFP rounds fuel consumption up to the nearest whole number. I had been rounding up to the nearest half-gallon, but building in even more buffer seems like a reasonable thing to do (especially since I don't really know whether the POH's estimates still hold, 40 years later!). Second, RTFP isn't as flexible and therefore may not be as accurate. For the four legs in my route, I was planning to fly three different altitudes. RTFP only allows you to specify one altitude to use for the whole flight, as far as I can tell. My POH says the burn rate is worse the higher you get, so that could have an impact on the whole trip. Those two factors would reasonably explain the difference in the time and fuel estimates.

Oh, I guess I learned a third thing: RTFP beats the pants off a manual E6B in the user-friendly and time-efficient categories!