Fun with /A vs GPS Direct

[denverpilot]

Just playing with OSH trip numbers...

KAPA KOSH Direct no fuel stops: 774 nm

IFR route utilizing /A airways and airports that have reasonable /A approaches at all fuel stops...not including full approaches, but including dist from VOR to Airport and doubling for departure: 889nm

VFR Direct with same fuel stops, no airways: 807nm

72nm difference between VFR and IFR to the same airports.

Just playing with it here. It's not meant to include climbs, descents, approaches, etc. Everything is at a fixed 130 knots GS to simplify.

For those playing along in Foreflight:

KAPA KOSH

KAPA PLAIN4.AKO AKO LBF KLBF LBF V172 OBH V219 SUX KSUX SUX V100 ALO KALO ALO V100 DBQ V341 MSN BAE KUNU RIPON FISKE KOSH

KAPA KLBF KSUX KALO KUNU RIPON FISKE KOSH

Just for other fun... Let's just say this is the only route I fly, ever. I want to go back and forth between KAPA and KOSH every time I hop in the airplane.

How many trips would it take to cost justify an $8000 Garmin 430 install? (And that's a pretty good deal.)

If we fly to the same fuel stops as the /A flight, $45 more in fuel at $6/gal.

8000/45... I need to make 178 one-way, or 89 round-trips to cost-justify the Garmin.

Change the fuel stops, it gets a little better.

Assuming best case that there's airports directly below the Direct route where ever we want them... It's a $69 difference in fuel, one-way.

8000/69... 116 one-way or 58 round-trip flights to recoup GPS direct.

Fun to play with the numbers.

There are, of course, lots and lots of other considerations. This was just for fun.

 

[flyingron]

I generally found that following the airways doesn't usually cost that much over filing direct. Duats will tell you how much of a lose your route is every time you file their flight planner. It's more an issue of operational convenience. My home airport, for instance, has a nice LPV approach down to 250' but no ILS.

 

[Dr. O]

The first time on your trip to OSH and you discover that your fuel destination is covered with morning fog as you arrive there with 30 minutes of fuel left that 430 is gonna look pretty good when you dial up the XM weather to find a clear area, then dial up the enroute low altitude charts, select an airport in the clear, and then with one button punch set the radio for calling ATC for an air-file IFR clearance and radar steer.. I suspect the $8K won't even cross your mind at that moment...

 

[EppyGA]

Nate, you're trying to use logic to substantiate the purchase of a 430?

 

[denverpilot]

Nate, you're trying to use logic to substantiate the purchase of a 430?

LOL, lord no. Toys aren't ever justifiable. I was just sitting there with most of the numbers already in front of me to answer the question so I played...

 

[ARFlyer]

I say get the 430 and that is not coming from someone who flies an aircraft with two of them!

I use it on every flight even if its just to give my exact position around our practice areas. All I have to do is spin the dial all the way right and read off my nearest page.

That page in an emergency could be a life saver. Yes, you have your iPad with FF but its often quicker to reach up and spin the dial. Also when I had a engine hiccup at night all I had to do was glace over at the MFD, which had our GPS map up, and see my nearest airport. I had peace of mind that I knew I was over an airport. A 1-2 second information sweep vs 30 secs or so looking at a chart at night and worrying about the engine.

I found this page very useful leaving from BPK after the Gaston's Fly-in. ATC wanted me to make position reports from BPK and FLP VOR. So all I had to do was flip between two sub pages and make my call. No looking at foreflight or a chart.

That page alone is worth getting the GPS.

Also as you have noticed ATC often gives your direct to, even if you can't, instructions.

You can also overlay any arrival, approach or depature for SA and direct to points for when ATC clears you. Very helpful when ATC clears you direct to ABCDE and all you have to do is input it and hit enter enter. ZFW is very consistent on giving me direct to to points I have never heard of and are not on the arrival plate. Again the nearest page or just a simple "can you spell it" call and your good.

So does this give you enough propaganda?

 

[BillTIZ]

GPS direct navigation means Great Circle route and a shorter distance.