Am I considered unstable at 150ft Above Minimums during CDFA?
Posted by fightermafia@reddit | flying | View on Reddit | 35 comments
Hi, if we are performing a CDFA approach via localizer, no glide slope and following recommended altitudes (descend angle 3.33deg), and the MAP point is at 1.2 NM with a minimum of 3500 ft, is it considered unstable if I am at 3650 ft at that point?
Just a few hours ago, I failed my multi-engine instrument rating check ride. One of the reasons the examiner gave was that I was 150 ft above the minimum at the MAP, which he said is out of tolerance and poses a risk for a hard landing if continued. He said I should remain within a +50 ft tolerance when over the MAP point, so a maximum of 3550 ft is allowed.
None of my instructors brought this up to me. It may be my fault for not paying enough attention, but isn't this a very tight tolerance? We do not have a glide slope, so how exactly am I supposed to maintain a very precise approach and remain below 3550 ft at the minimums? I always thought remaining above the minimum was enough, provided we can make it to the threshold with acceptable performance values for example, a vertical speed not higher than 1000 fpm or a threshold crossing speed not excessively higher than the reference speed.
hawker1172@reddit
The real question here is why was CDFA technique being done? Dive and drive
Apprehensive_Cost937@reddit
They will likely never need to, let alone want to, fly a dive and drive approach in their entire career.
Dive and drive approaches belong in the graveyards of history, alongside many pilots who died flying them.
hawker1172@reddit
It’s a better method for the GA training and checking environment.
Apprehensive_Cost937@reddit
How about the real world, for which training should be focused towards?
hawker1172@reddit
Key word should. OP has a checkride failure by not sticking to the tride and true dive and drive method on an examination. Im not arguing CDFA isn’t better but do what you have to do to pass your checkride. Ideally you should be trained and proficient on both methods. Most accidents with dive and drive come from lack of proficiency or due regard for safety.
badorianna@reddit
Weird thing to be examined for multi. When are you ever expected to fly CDFA as a single pilot? Are you supposed to memorize the entire chart's altitude vs. DME checks? Why are we even hand flying CDFA with no flight directors on FPA or VS to begin with?
Independent-Reveal86@reddit
It’s the only way I’ve ever flown an approach, single pilot or not.
bhalter80@reddit
Some of us are old and remember dice and drive because you might pop out of the clouds.
I teach what my betters at the FAA prefer and I'll follow my employer's SOP as written but in my personal flying both are valid and have different uses
Independent-Reveal86@reddit
Sure. I’m not saying don’t do it, just that CDFA is not a problem single pilot.
bhalter80@reddit
I agree, and most NPs are RNAV-LNAV approaches where you get +V vertical guidance that IS the CDFA path.
Independent-Reveal86@reddit
This is a failure in your charting. I’ve been instrumental flying in Australia since 2003 and all of the approach charts have an advisory DME height profile. You just set yourself a rate of descent and check your crossing altitudes. You don’t need to be looking at the chart every mile, you know it’s about 320’ per mile, so you can do most of it in your head and have some key reference checks along the way. It’s not difficult.
bhalter80@reddit
Agreed, old VOR approaches which weren't built for this and even some of the new RNAV-LNAV approaches that would have the descent point start between fixes are poorly built/charted
Apprehensive_Cost937@reddit
You can just reference the distance checks as you pass them, and crosscheck with altimeter - no need to memorise the table.
CDFA can be flown in any airplane really, from the basic C150 to the most modern A350, single or multi pilot.
Apprehensive_Cost937@reddit
As you haven't provided the exact approach, it's hard to tell. I know Turkey isn't part of EASA, but they largely follow its framework. The general height limit on an EASA IR test/check is +/- 100ft, so unless examiner is applying some sort of a discretion due to e.g. turbulence, then yes, you probably were outside of limits.
__joel_t@reddit
What country are you in? Most folks here are in the USA, where there is no separate multi-engine rating.
dromzugg@reddit
In Canada we do multi engine before multi IFR. Or you can do a single engine IFR.
mirassou3416@reddit
The poster was citing how we usually approach multi cert--IFR rating then just one checkride with Multi IFR but circumstances may have OP not having an IFR rating and first getting the multi VFR rating
mirassou3416@reddit
Of course there is if you do multi VFR then multi IFR later on
fightermafia@reddit (OP)
Turkiye. I first received my instrument rating for SE fist, then CPL and ME. But failed at the last turn for MEIR.
FlyingSceptile@reddit
Could have done Private-Multi and now is adding on the Instrument
Right-Suggestion-667@reddit
Yes. I wanna say the ACS is -0 +100 for a non precision approach so yeah. If you elected to go missed then it would have been kosher
bustervich@reddit
If I’m understanding you correctly, you were at the missed approach point 150’ above the MDA?
For a lot of non precision approaches, the MAP is basically at the runway threshold, so if you find yourself at the MAP 150’ above the MDA, is there anyway you could actually land safely? If you’re planning a CDFA on your own you ideally want to hit your DDA at the visual descent point, not the MAP.
Independent-Reveal86@reddit
Your examiner should have discussed tolerances before the flight so you know what’s expected. That said, if you’re 150 high at the MAP then you’re not making the most of the minima to get you visual, so regardless of if it should be a fail, it’s very sloppy flying.
SMELLYJELLY72@reddit
CFDA is some new acronym lore for me but i’m assuming you’re talking about DDA type approaches?
The bottom line is the acs tolerance for an approach is -0, +100. DDA or not. The DDA is 50’ higher to assume for dipping below minimums during a go-around, since you were in the middle of descending. that way you go below a “fake” hard altitude, not a real hard altitude. going above the real hard altitude at +150’ is a bust according to the acs.
__joel_t@reddit
Continuous Descent Final Approach, when you attempt to maintain the same stabilized approach angle on a non-precision approach, as opposed to a dive-and-drive approach.
SMELLYJELLY72@reddit
okay, then we are talking DDA. i only learned about these when i joined the airlines where we call it CANPA.
which makes the point of the DPE even more correct in my opinion. the point of CANPA or CDFA is to basically pretend there’s a glideslope by flying a constant descent. during the descent you should continuously check your altitude and make sure it’s lining up with where you should be, and adjusting from there. honestly it’s a little more difficult than diving and driving, but much more safe.
my question is to the OP: do you think you were set up for a safe landing? if the DPE questioned your ability to make a landing off the approach, you must’ve been +150’ veeerrry close to the runway. which would unfortunately be grounds for an unsat.
listen i totally get being upset in the moment. sulk today but critically think about your notice of disapproval tomorrow.
x4457@reddit
Dunno what DDA or CANPA are, CDFA is the industry standard terminology for this now.
SMELLYJELLY72@reddit
constant-angle non-precision approach, and like i said i never heard of it until that’s how my airline taught non precision approaches.
got my instrument in 2021 so is this a new thing that they’re teaching?
x4457@reddit
It has existed since before 2021, that's for sure. Might have just fallen through the gaps for you.
kmac6821@reddit
Which is what that poster is referring to. A derived decision altitude is part of CDFA.
Rainebowraine123@reddit
The -0/+100 is the tolerance for maintaining MDA. Technically the ACS doesn't say you have to get there.
Rainebowraine123@reddit
I'd be emailing the FSDO. The ACS doesn't say you have to reach the MDA, just that you can't go below it ("and altitude, if applicable, above MDA +100/-0..." for the final approach segment). Obviously you cant be MDA +100/-0 immediately on the final approach segment. The +100/-0 starts once you reach within 100 feet of the MDA. Then it says continue or go missed depending on if you have the required visual references or not.
__joel_t@reddit
I don't think OP is in the USA.
Rainebowraine123@reddit
Oop, deleting my comment lol
rFlyingTower@reddit
This is a copy of the original post body for posterity:
Hi, if we are performing a CDFA approach via localizer, no glide slope and following recommended altitudes (descend angle 3.33deg), and the MAP point is at 1.2 NM with a minimum of 3500 ft, is it considered unstable if I am at 3650 ft at that point?
Just a few hours ago, I failed my multi-engine instrument rating check ride. One of the reasons the examiner gave was that I was 150 ft above the minimum at the MAP, which he said is out of tolerance and poses a risk for a hard landing if continued. He said I should remain within a +50 ft tolerance when over the MAP point, so a maximum of 3550 ft is allowed.
None of my instructors brought this up to me. It may be my fault for not paying enough attention, but isn't this a very tight tolerance? We do not have a glide slope, so how exactly am I supposed to maintain a very precise approach and remain below 3550 ft at the minimums? I always thought remaining above the minimum was enough, provided we can make it to the threshold with acceptable performance values for example, a vertical speed not higher than 1000 fpm or a threshold crossing speed not excessively higher than the reference speed.
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