GNS Part 7 VNAV

[@KEVINBURKE-h9e]

Great Video: I learned a lot as usual

[@wwm0611]

Continues to be a great series - happy Anniversary- thanks for all you both do!

[@bengoldshlager4182]

Great lesson. Thank you!

[@unemploymentcp]

Well done, Mike and Bryan.

[@da40fan27]

Thanks for this. Good to be reminded we can use this for climbs. Also useful to know that VNAV does not work when Direct To (vice flight plan). Fortunately, I use my FS210 to enter data so even for direct to flights I create and transfer a flight plan.

[@peteallennh]

One thing I don't understand. Why is it that when you were headed to ZENAP and you set your altitude to 12000 the VSR was still decrementing? If you had attained the target altitude of 12000, shouldn't it zero-out?

[@CapnMikeCFI]

Once you're at the programmed altitude, yes. In this case, I was still climbing, so it showed me the VSR from my current altitude. The simulator has some climb rate it uses, so an altitude change is not instantaneous. At about 29:00, once the simulator gets to 12,000, the VSR is indeed zeroed out. Thanks for the question!

[@mannypuerta5086]

I find the use of VNAV on the 430/530 to be an onerous, clunky process…and the 430/530 VNAV won’t interface with the GNC 500 autopilot. The newer GTN’s will. I just use five times the required altitude to lose (and use field elevation for a buffer) for descent planning, remembering that the typical 300’/mile is the desired slot when close to destination. At the airline I saw so many depend on the FMS VNAV and then have to use the speed brakes to compensate and correct for the poor profile. You could always tell who were the ex-DC-8 pilots when they did the descent planning. There were no speed brakes on the DC-8, so you had to plan it properly or use the inboard reversers, which most operators prohibited except for emergency descents.

[@CapnMikeCFI]

Hah! Yes, I remember as a newly minted IFR pilot back in the day, and a private pilot before that, I didn't get much training on descent planning. At the time, I was flying slow enough airplanes that never went high enough for it really to be much of an issue. As I got into faster and higher-flying equipment, it certainly does become more critical. I use the 3* the altitude rule, and back up the VNAV "guidance" (that word is doing a lot of work in the context of a GNSx30W navigator!) with some mental math. And I absolutely agree that the x30 interface is clunky and onerous. I call all the knob twisting and pushing the "Twist and shout" data entry method!

[@Heathfx5]

one thing that is a gotcha for me is the additional 30 kts I pick up in the descent. I have not used the vnav feature of my 530 yet, but I'm thinking I need set a -400 FPM target, so I can trick it into giving me more time to descend. I could slow down, but in a cessna 210 if I'm at 50% cruise power I can only pull 2 more inches of power before triggering the landing gear alarm. The next factor is if I'm at higher cruise power, say 75%, I don't like chopping the power from 28 inches to 20 inches all at once because of how bad the tsio-520 is with shock-cooling. I like to gradually pull power by 1 inch per minute, so because I could easily be hitting 200 kts true at 27in + 500 fpm descent I need to start my decent several minutes earlier.

[@CapnMikeCFI]

You're absolutely right about that. Your technique of programming your 530 with a 400FPM descent is not a bad way to compensate. I also do power-on cruise descents - I figured I put all that time and fuel into getting up to altitude, I wanna capitalize on it in the descent! - but I leave the VNAV page programmed at 500FPM, and just manually start down when it gets to about 400VSR. I also back it up with the Descent to Dest figure on ForeFlight, and back it up even further with mental math on required descent rates.