Dive and Drive or CDFA? | KRNT Renton, Washington RNAV 34

Рет қаралды 6,917

3 ай бұрын

Let's shoot this non precision RNAV into KRNT at Renton to look at different ways to descend on the approach.
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Пікірлер: 27

@AlexGac 3 ай бұрын

I think you nailed it with the avionics choices in your video! With minimal automation, I like to chop and drop. I get under any cloud bases quicker (if bases are high enough at all), and it's easier for me to maintain an MDA _while looking for the runway environment_ then it is for me to make a constant descent towards the MDA while looking. With more automation, and especially with a coupled AP, a CDFA feels like a light workload even while scanning for the runway environment.

@JakeSpeed1000 3 ай бұрын

I dive and drive. I can hopefully get under the cloud layer faster and have more time to spot the runway.

@seattleraf 3 ай бұрын

My home airport!! :D I’m finishing up instrument training and tend to prefer “dive and drive” (though don’t love that term). My flight school has G1000s and the fake glide path has caught me out and busted step-down altitudes including on this very approach. I know it’s something I can just learn to be aware of - but keeping it simple and just flying the step downs manually reduces workload for me and also constantly remind me that I’m flying an approach with an MDA and not a DA.

@flightinsight9111 3 ай бұрын

Glad it's your home field! The advisory glidepath definitely can add extra confusion, but I'm always happy to have it!

@gonetoearth2588 3 ай бұрын

Nice video as usual! One thing I would add is there are MANY advantages to Jepp charts one of which is that the approach plates will have the decent rate in ft/min depending on GS and in some cases WHERE to initiate the CDFA decent so you don't bust the altitudes....This is a VERY IMPORTANT point as the ADVISORY GS on these approaches could cause you to be lower than charted.

@thebadgerpilot 3 ай бұрын

4:25 I think you have a slip in your verbiage there. 1000fpm is an aggressive descent, but it's stable as long as it remains a consistent 1000fpm. "Destablized" or unstable would be if you're aiming for a 1000fpm descent but it's fluctuating between 800-1200fpm. You can just as easily be unstable when aiming for a docile 300fpm descent. Known pitch/power settings are quite helpful here.

@jimallen8186 3 ай бұрын

“Dive and drive” is a misnomer. The stepdown is really descend and drive and it is still stable. We should properly distinguish between climbs and zooms and descents and dives. Climbs and descents involve power differences such that chemical energy rates impact potential energy. Accelerations and decelerations do chemical to kinetic. Zooms and dives, however, are unique in that these are the trades potential and kinetic. You don’t “dive and drive” an approach.

@jimallen8186 3 ай бұрын

Search Medium for Improve your Landings with AOA and Power Techniques for more on descents versus dives and zooms versus climbs.

@dragoclarke9497 3 ай бұрын

CDFA whatever I'm flying. But I did fly a B752 for 20 years so that may have influenced my thinking 😊

@knackeredish 3 ай бұрын

Don’t land too long at KRNT. You’ll go down the seaplane ramp and into the water!

@hrljr76 3 ай бұрын

Lol. 😂

@bludybrains 3 ай бұрын

CDFA absolutely the easier and safer approach. Plus you can always dip below GP as you approach MAP so that you have a little bit of time at the MDA before going missed.

@johnhoward2000yt 3 ай бұрын

Refer to AIM 7-3-1 for guidance on effect of non-standard temperature on actual/true height above the ground.

@notsoancientpelican 3 ай бұрын

Thousands of feet above airport x degrees below standard x 4 will give you the error. At 500 ft above airport (typical MDA) with a 20 deg C colder than standard, you will be 0.5 x 20 x 4 = 40 feet closer to dirt than what your altimeter says. In practical terms, this is no problem at all.

@victorchang3377 3 ай бұрын

why is it possible to be on the glidepath but cross the fix below stepdown altitude on hotter than standard days?

@TheFlyingZulu 3 ай бұрын

Hotter or colder days = different altimeter settings. If you have X-plane or MSFS try it out by changing the temperature and/or altimeter settings... I'm going to do that and see how it exactly it affects the situation.

@TheFlyingZulu 3 ай бұрын

So I just tried this out in X-plane 11 on LPV approach using the stepdown altitudes instead of the glide slope... First I tried a cold temperature of 40 degrees F with at local altimeter setting of 29.50 and the stepdown fix correlated with the glide slope... I then turned up the temperature to 90 degrees F and the altimeter setting to 31.50 and reset my altimeter on my plane and guess what... the glide slope correlated with the correct altitude and stepdown fix... I don't know what Dan is talking about heat making it so that you're on glidepath but below the stepdown fix....

@BradAboutYou 3 ай бұрын

The tolerance for your altimeter, while on the ground, is within 75ft of field elevation. You don’t have the same tolerance on an approach. It’s very possible to be off by .01 on your setting, or the altimeter setting changes while you’re on approach. He’s trying to say it’s possible because the glide path is ONLY advisory. I think he’s driving home the point you shouldn’t treat an advisory glide path as anything but situational awareness and you’re still responsible. Sims are a lot different in this way to actually flying.

@colinkokholoh 3 ай бұрын

At any point along a GPS-based glideslope, what would your altitude indicator, which is baro-based, say on a cold/low-pressure day vs. a hot/high-pressure day? On a cold day it might say 1100 ft. On a hot day, that same physical point in space would cause your baro altimeter to show something lower. Since the step-down minimums are for you to apply to your baro altitude-indicator, not your GPS, you may be violating stepdowns on a hot day when you wouldn't if it was colder.

@mikoajjozwiak2487 3 ай бұрын

Is RNAV still NPA approach? Thought its APV now

@avitor500 3 ай бұрын

It will depends on if it is 3D( lnav+vnav or LPV)= APV. If it is Lnav only(2D), then it is NPA.

@clydemactavish3457 3 ай бұрын

RNAV approaches can have different minimums depending on approach and aircraft capability. An LNAV doesn't have vertical guidance and uses step-downs like shown here and would still be considered a non-precision approach with no vertical guidance. An RNAV approach that has LNAV/VNAV or LPV minimums, unlike the one in the video has vertical guidance can be flown using that vertical guidance. An LPV is still the only one that relies on WAAS which is an approach and aircraft requirement to use LPV which is basically like flying an ILS but using GPS. But this is considered "precision-like" but will even be accepted flat out as a precision approach in the new Instrument rating airman certification standards coming late May. (anyone else feel free to add or correct anything I'm missing)

@MWONG06 3 ай бұрын

All RNAV approaches are still non-precision, even with WAAS for LPV. LNAV+VNAV and LPV offer vertical guidance to typically allow for lower MDA, but still not considered precision approaches.

@vissj1 3 ай бұрын

CDFA and I add 50ft to the published minima

@jimallen8186 3 ай бұрын

Increase your power to keep your speed up? How about add power to level off.

@jimallen8186 3 ай бұрын

Sorry, forgot you were doing a coupled run.

@notsoancientpelican 3 ай бұрын

GA is not airline flying. GA's utility comes from ability to fly into all kinds of little airports that have all kinds of NP approaches. The BEST way to fly an NP is Dive and Drive. D & D gives you then BEST chance of seeing the runway with adequate time to make a good landing. If you aren't able, comfortable, confident and proficient doing D&D, you should take up boating as a hobby. GA Flying: It's not for everybody.