Cessna 208B crash short of Burley Municipal Airport

[Jackk]

There are a lot of errors in the video analysis. First, the advisory GP does not change for the procedure, it remains at 3.75 degrees, which crosses HIKLO nominally at 6206 feet and JAMID at 4832 feet. The assertion that the GP changes after JAMID is false and manufactured. I used the chart information and the equations used by the FAA to determine the GP height at a distance from the threshold. They take the curvature of the earth into account. The TSO requires that the advisory GP clear all step down fixes and that it is a constant angle. I simulated this using the GTN trainer and took screenshots of the indications at the advisory GP intercept at 7000 feet, which my calculations indicate would occur approximately at 2 NM before crossing HIKLO.

Here is the screenshot close to GP intercept.

View attachment 107071


Here is the screenshot close to crossing HIKLO (my calculation is it should occur at 6206)

View attachment 107072

Here is the screenshot close to crossing JAMID (my calculation is it should occur at 4832)

View attachment 107073

The advisory GP is not suited for descent below the MDA, so any descent to the runway must be visual. The inoperative VASI is shown in the AFD as being 3.5 degrees with a TCH of 46 feet and a displaced threshold of 305'. Although there is an FDC NOTAM to delete the note regarding the VGSI difference, there isn't a NOTAM indicating that the VASI is out of service, so the current chart still displays a VASI and the AFD still indicates it is in service.

I believe the YouTube video said the VASI wasn’t inop, it was turned off, due to the tower they built into the approach path.

 

[luvflyin]

My understanding is it will take you down like a ILS, hitting every altitude constraint on the dot, HOWVER when you hit MDA you level off and you’re VFR mode or you’re TOGA at the missed.

Doing a 100% visual landing appears to be even more important after now seeing the FAA will not deactivate illegal approaches, or take legal action, it’s all carrot no stick.

No it won’t. An ILS Glidesope won’t even do that. But if on a Glideslope you do not have to level off at the FAF or a closer in Fix like you do on these advisory things.

 

[Jackk]

No it won’t. An ILS Glidesope won’t even do that. But if on a Glideslope you do not have to level off at the FAF or a closer in Fix like you do on these advisory things.

So a RNAV complementary glide slope won’t meet or exceeded the step down fixes?

If I were to fly one, I’d bust a step down fix?

 

[John Collins]

The advisory GP on an NPA is to provide an aid to descending to the MDA using a constant angle descent. It is not part of the approach and does not apply below the MDA. It is a permitted option that manufacturers of GPS systems may provide. It is not charted or part of the procedure itself. An NPA procedure gets you to an MDA which has obstacle protection based on a level 250 foot surface above the highest obstacle. The VDA may take you through an obstacle if you follow it below the MDA, you have to see where you are going when below the MDA and if there are obstacles along your path to the runway, you have to avoid them visually. If one does not see the stipple emanating from the MDA to the threshold, then the visual segment is not clear on a 34 to 1 slope. If there is no VDP charted, then the visual segment is not clear on a 20 to 1 slope. There may also be a note on the chart "Visual Segment - Obstacles" indicating that the visual segment is may require maneuvering below the MDA to avoid obstacles.

 

[Jackk]

The advisory GP on an NPA is to provide an aid to descending to the MDA using a constant angle descent. It is not part of the approach and does not apply below the MDA. It is a permitted option that manufacturers of GPS systems may provide. It is not charted or part of the procedure itself. An NPA procedure gets you to an MDA which has obstacle protection based on a level 250 foot surface above the highest obstacle. The VDA may take you through an obstacle if you follow it below the MDA, you have to see where you are going when below the MDA and if there are obstacles along your path to the runway, you have to avoid them visually. If one does not see the stipple emanating from the MDA to the threshold, then the visual segment is not clear on a 34 to 1 slope. If there is no VDP charted, then the visual segment is not clear on a 20 to 1 slope. There may also be a note on the chart "Visual Segment - Obstacles" indicating that the visual segment is may require maneuvering below the MDA to avoid obstacles.

Bot?

 

[John Collins]

So a RNAV complementary glide slope won’t meet or exceeded the step down fixes?

If I were to fly one, I’d bust a step down fix?

If you fly the advisory glidepath, you are still required to cross any fix at or above the minimum charted altitude and you may not descend below the MDA unless you are visual and meet the visibility requirements for the procedure. On a hot day, if you are precisely on the advisory glidepath, you are likely to cross fixes below the charted minimum, but probably not by much from the FAF to the threshold. Outside the FAF, it is much more likely to be noticed.

 

[Jackk]

If you fly the advisory glidepath, you are still required to cross any fix at or above the minimum charted altitude and you may not descend below the MDA unless you are visual and meet the visibility requirements for the procedure. On a hot day, if you are precisely on the advisory glidepath, you are likely to cross fixes below the charted minimum, but probably not by much from the FAF to the threshold. Outside the FAF, it is much more likely to be noticed.

That was not the question.

Question had nothing to do with regs or MDA

If you fly the complementary glide path on a Garmin,Honeywell, will you cross the fixes at or above the prescribed altitudes?

 

[luvflyin]

So a RNAV complementary glide slope won’t meet or exceeded the step down fixes?

If I were to fly one, I’d bust a step down fix?

Not always. They design it be. But it assumes an accurate altimeter and a standard day. I’d just keep going to. Unless it was way off. Like maybe almost a mile early and I wasn’t outta the goo yet and could see the ground. That far out and I would have lost faith in the box

 

[John Collins]

If you fly the complementary glide path on a Garmin,Honeywell, will you cross the fixes at or above the prescribed altitudes?

It totally depends on the system that is providing vertical guidance. If it is based on WAAS or GPS for the vertical, there is no assurance that the guidance will cross a fix at or above the minimum altitude. With a system based on baro-VNAV, it should provide vertical guidance that matches the altimeter indication and should be at or above the minimum altitude. So with a GNS530W, the answer is not necessarily.

 

[TrueCourse]

I would not be flying an advisory glidepath, or whatever a particular avionics manufacturer calls it, with the thought it guarantees you will cross at or above any step down fix crossing heights.

Couple of other thoughts. Plugging in a visual approach where a precision approach is offered doesn’t mean it will offer you the same glide path that the precision approach offers for obstacle clearance. It will default to 3 degrees.

Also, as mind boggling as it may seem, following a localizer or glide slope with no deflection doesn’t mean you will be lined up on centerline when you break out into VMC. See the ERJ-145 off runway accident that occurred during winter conditions at KPQI Spring 2019.

 

[Turbo-Arrow-Driver]

The FAA does not state you must follow the advisory GP. With dive and drive, you are very likely to be below the advisory GP and that is permitted. The advisory GP is simply a guide or one way of descending after passing a fix at or above a minimum crossing altitude to the next minimum altitude. It is not the only way.

Okay, got it. I think I misinterpreted your earlier post. It's okay to follow the advisory GP, but you must also comply with indicated altitude constraints per the published approach.

Just FYI, I flew a couple practice approaches recently, waiting to intercept the advisory GS after IF, then following that down. It really does ease the (single pilot) workload when you only need to cross-check the altitude restrictions instead of either diving/level off/driving or trying to time the descent on the fly.

 

[SkyDog58]

There's a whole thread on the video. Stop taking Gryder as gospel. What he doesn't and can't know he just makes up to fit a narrative. It takes longer than a couple weeks to do an in depth investigation and put together and edit a video.

https://www.pilotsofamerica.com/community/threads/gryder.138030/

Anybody who takes anything Gryder says as gospel should reevaluate their own knowledge and judgment.

 

[Jackk]

Anybody who takes anything Gryder says as gospel should reevaluate their own knowledge and judgment.

Perhaps you could answer this, was the man in the YouTube videos correct or incorrect about the tower heights?

Taking anything anyone, including the FAA or NTSB, says as gospel is a bad idea.

 

[luvflyin]

I would not be flying an advisory glidepath, or whatever a particular avionics manufacturer calls it, with the thought it guarantees you will cross at or above any step down fix crossing heights.

Couple of other thoughts. Plugging in a visual approach where a precision approach is offered doesn’t mean it will offer you the same glide path that the precision approach offers for obstacle clearance. It will default to 3 degrees.

Also, as mind boggling as it may seem, following a localizer or glide slope with no deflection doesn’t mean you will be lined up on centerline when you break out into VMC. See the ERJ-145 off runway accident that occurred during winter conditions at KPQI Spring 2019.

Link to that?? Was the Localizer malfunctioning, published offset or did they fail to publish an offset?

 

[Racerx]

Perhaps you could answer this, was the man in the YouTube videos correct or incorrect about the tower heights?

Taking anything anyone, including the FAA or NTSB, says as gospel is a bad idea.

According to ADSB, did she not bust MDA? Twice?

If the FAA was lied to about the tower height, why would they hide it? Seems that would be the easiest scapegoat ever.

 

[TrueCourse]

Link to that?? Was the Localizer malfunctioning, published offset or did they fail to publish an offset?

https://data.ntsb.gov/Docket?ProjectID=99050

ILS Critical area was not clear and it wasn’t a momentary problem.

 

[Jackk]

According to ADSB, did she not bust MDA? Twice?

If the FAA was lied to about the tower height, why would they hide it? Seems that would be the easiest scapegoat ever.

Maybe, but ADSB isn’t all that accurate

 

[John Collins]

ADS-B provides both geometric altitude (a form of GPS altitude) and pressure altitude. They have a precision of 25 feet. The accuracy of the geometric altitude should be pretty good most of the time.

 

[Salty]

ADS-B provides both geometric altitude (a form of GPS altitude) and pressure altitude. They have a precision of 25 feet. The accuracy of the geometric altitude should be pretty good most of the time.

True, but generally speaking, the data comes from someone that may or may not augment it with "estimated" data. Especially at low altitudes. I would take it with a grain of salt without knowing exactly how it was collected.

 

[John Collins]

Doing a 100% visual landing appears to be even more important after now seeing the FAA will not deactivate illegal approaches, or take legal action, it’s all carrot no stick.

The IFR approach is not an illegal procedure. The MDA is at least 250 feet above the obstacle. An IFR straight in approach procedure does not provide obstacle protection below the MDA and requires the pilot see and avoid any obstacles visually. There is at least one approach in NY that if you follow the +V below the MDA, it will take you through the side of a ridge.

 

[Palmpilot]

...There is at least one approach in NY that if you follow the +V below the MDA, it will take you through the side of a ridge.

Yikes!

 

[luvflyin]

The IFR approach is not an illegal procedure. The MDA is at least 250 feet above the obstacle. An IFR straight in approach procedure does not provide obstacle protection below the MDA and requires the pilot see and avoid any obstacles visually. There is at least one approach in NY that if you follow the +V below the MDA, it will take you through the side of a ridge.

Which one?

 

[John Collins]

I wrote an article on the topic of dive and drive and featured this approach in the April 2014 edition of IFR magazine. Since then, the note "Visual Segment- Obstacles" was added to the procedure profile view, but otherwise this procedure is essentially unchanged (the VDA was actually decreased a little from 3.02 degrees to 3.0 degrees but the TCH was raised from 40 feet to 50 feet).

Sydney NY, N23. MDA is 2140. Here is a screenshot using the Garmin Trainer:



Here is a Google Earth view.



Here are the FAA and Jeppesen chart depictions:

 

[Jackk]

The IFR approach is not an illegal procedure. The MDA is at least 250 feet above the obstacle. An IFR straight in approach procedure does not provide obstacle protection below the MDA and requires the pilot see and avoid any obstacles visually. There is at least one approach in NY that if you follow the +V below the MDA, it will take you through the side of a ridge.

why did the FAA write a letter that they would no longer fund the field?

 

[exncsurfer]

Is this what that NY approach is supposed to look like?, on google earth, this is 5 miles out, camera at 2700 ft., i don't see any airport, i see a hill:

yellow line is the runway extended centerline(roughly)

 

[John Collins]

why did the FAA write a letter that they would no longer fund the field?

Do you have a link to the FAA letter. I presume it relates to some duty that if the airport accepts FAA funds, the airport must comply with, but without reading it, I can't comment intelligently. This is the current NOTAM on the approach procedure.

!FDC 2/5029 BYI IAP BURLEY MUNI, BURLEY, ID.
RNAV (GPS) RWY 20, ORIG-D...
MISSED APPROACH: CLIMBING LEFT TURN TO 7000 DIRECT IREME AND HOLD,
CONTINUE CLIMB-IN-HOLD TO 7000.
DELETE NOTE: DME/DME RNP - 0.3 NA.
PBN REQUIREMENTS NOTE: RNP APCH - GPS.
DELETE NOTE: WHEN LOCAL ALTIMETER SETTING NOT RECEIVED, USE TWIN
FALLS ALTIMETER SETTING AND INCREASE ALL MDA 80 FT.
DELETE NOTE: VGSI AND DESCENT ANGELS NOT COINCIDENT (VGSI ANGLE
3.00/TCH 37).
DELETE NOTE: HELICOPTER VISIBILITY REDUCTION BELOW 3/4 SM NOT
AUTHORIZED.
NOTE: RWY 20 HELICOPTER VISIBILITY REDUCTION BELOW 1 SM NOT
AUTHORIZED.
LNAV CAT C VIS 1 1/8.
DELETE FAS OBST: 4304 TOWER 423331N/1134454W.
CHART FAS OBSTACLE: 4291 TOWER (16-022120) 423331N/1134454W.
THIS IS RNAV (GPS) RWY 20, ORIG-E. 2204071227-PERM

The NOTAM reduces the height of the charted FAS obstacle by 12 feet, but makes no change in the MDA or the VDA angle.

 

[Jackk]

Do you have a link to the FAA letter. I presume it relates to some duty that if the airport accepts FAA funds, the airport must comply with, but without reading it, I can't comment intelligently. This is the current NOTAM on the approach procedure.



The NOTAM reduces the height of the charted FAS obstacle by 12 feet, but makes no change in the MDA or the VDA angle.

It’s was the FAA letter in the video.

 

[455 Bravo Uniform]

@John Collins is awesome. That is all...

 

[Turbo-Arrow-Driver]

Do you have a link to the FAA letter.

Here: https://oeaaa.faa.gov/oeaaa/external/letterViewer.jsp?letterID=321199198

 

[Racerx]

Didn't read the letter or watch the video. But the FAA first threatened the funding thing in 2014. And it had nothing to do with the potato factory.

https://www.kmvt.com/content/news/Burley-losing-funding-for-airport-486309301.html

https://www.aviationpros.com/airpor...rley-airports-shortcomings-to-local-officials

 

[John Collins]

why did the FAA write a letter that they would no longer fund the field?

I assume they wrote the letter because the obstacle evaluation called for by part 77 did not take place and they were following an FAA policy in such cases. In the case of the non precision approach procedure, it did not affect the procedure itself other than the corrections found in the NOTAM. It is interesting to note that in 8260.3E (aka TERPS), section 1-2-1 describes the eligibility for an IFP and in section 1-2-3 Approval, it has this statement:

e. Obstacle marking and lighting. Obstacles that penetrate 14 CFR Part 77 imaginary surfaces are obstructions and; therefore, should be marked and lighted per AC 70/7460-1, Obstruction Marking and Lighting. Those penetrating the 14 CFR Part 77 approach and transitional surfaces should be removed or made conspicuous under AC 70/7460-1 (or military equivalent). Do not deny instrument approach procedures due to inability to mark and light or remove obstacles that violate 14 CFR Part 77 surfaces

I presume this is because the visibility and MDA requirements permit approaches with obstacles in the visual segment and the pilot is supposed to avoid them visually and meet the requirements of 91.175(c)(3) in order to descend below the MDA.

 

[John Collins]

Here: https://oeaaa.faa.gov/oeaaa/external/letterViewer.jsp?letterID=321199198

This link does not produce the letter. I have been seeing this for the last two days:


If you can download and post the letter, it would be appreciated.

 

[Piperonca]

This it?

 

[luvflyin]

I wrote an article on the topic of dive and drive and featured this approach in the April 2014 edition of IFR magazine. Since then, the note "Visual Segment- Obstacles" was added to the procedure profile view, but otherwise this procedure is essentially unchanged (the VDA was actually decreased a little from 3.02 degrees to 3.0 degrees but the TCH was raised from 40 feet to 50 feet).

Sydney NY, N23. MDA is 2140. Here is a screenshot using the Garmin Trainer:

View attachment 107143

Here is a Google Earth view.

View attachment 107141

Here are the FAA and Jeppesen chart depictions:

View attachment 107139

View attachment 107140

It doesn’t look like that Approach has a VDA. If it does, why isn’t it on the Gov Chart? There is an angle that can be calculated from LOTMY at 2700 down to the runway and Jepp puts it on the CHART. That’s the angle LNAV+V will give you, but that’s not really a “VDA”

 

[John Collins]

The approach has a VDA of 3 degrees/TCH 50 feet. The FAA doesn't chart a VDA when the note "Visual Segment - obstacles" is included in the profile view. Jeppesen has a different opinion and they chart the VDA. +V is included in the Jeppesen and Garmin Navdata.

 

[luvflyin]

The approach has a VDA of 3 degrees/TCH 50 feet. The FAA doesn't chart a VDA when the note "Visual Segment - obstacles" is included in the profile view. Jeppesen has a different opinion and they chart the VDA. +V is included in the Jeppesen and Garmin Navdata.

View attachment 107225


View attachment 107226

Ok. A matter of semantics maybe. But a ‘quote’ VDA ‘unquote’ is a specific term and is referenced on the FAA’s Approach Data. That Garmin and Jeppesen calculate an angle that you can vertically descend on and include it in their data bases so they can do their +V thing, doesn’t make it a “VDA.” I think sometimes the distinction is pertinent in discussions like this one.

EDIT: Looks like if the Chart Maker does it their self, it’s still “VDA”. See post #78 below. And #80 for a quicker read of the part that refers to this.

 

[Turbo-Arrow-Driver]

Ok. A matter of semantics maybe. But a ‘quote’ VDA ‘unquote’ is a specific term and is referenced on the FAA’s Approach Data. That Garmin and Jeppesen calculate an angle that you can vertically descend on and include it in their data bases so they can do their +V thing, doesn’t make it a “VDA.” I think sometimes the distinction is pertinent in discussions like this one.

To toss a bit more into the word salad, here's what the FAA's Instrument Flying Handbook (2012 Edition) has to say about VDA:

The Vertical Descent Angle (VDA) found on nonprecision approach charts provides the pilot with information required to establish a stabilized approach descent from the FAF or stepdown fix to the TCH.​

The FAA's Instrument Procedures Handbook (2017 Edition) says something signficantly different:

The VDA provides the pilot with advisory information not previously available on nonprecision approaches. It provides a means for the pilot to establish a stabilized descent from the FAF or step-down fix to the MDA. ... However, pilots should be aware that the published angle is for information only − it is strictly advisory in nature. There is no implicit additional obstacle protection below the MDA. Pilots must still respect any published stepdown ixes and the published MDA unless the visual cues stated 14 CFR § 91.175 are present, and they can visually acquire and avoid both lit and unlit obstacles once below the MDA. The presence of a VDA does not guarantee obstacle protection in the visual segment and does not change any of the requirements for lying a nonprecision approach.​

And this comes from the FAA's Digital Terminal Procedures Supplemental:

An advisory vertical descent angle (VDA) is provided on non-vertically guided conventional procedures and RNAV procedures with only a minimum descent altitude (MDA) to assist in preventin controlled flight into terrain. On Civil (FAA) procedures, this information is placed above or below the procedure track following the fix it is based on. Absence of a VDA or a note that VDA is not authorized indicates that the prescribed obstacle clearance surface is not clear and the VDA must not be used below MDA.
​

 

[John Collins]

And this current guidance in the AIM, 5−4−5. Instrument Approach Procedure (IAP) Charts:

k. Vertical Descent Angle (VDA). FAA policy is to publish a VDA/TCH on all nonprecision approaches except those published in conjunction with vertically guided minimums (i.e., ILS or LOC RWY XX) or no-FAF procedures without a step-down fix (i.e., on−airport VOR or NDB). A VDA does not guarantee obstacle protection below the MDA in the visual segment. The presence of a VDA does not change any nonprecision approach requirements.
1. Obstacles may penetrate the obstacle identification surface below the MDA in the visual segment of an IAP that has a published VDA/TCH. When the VDA/TCH is not authorized due to an obstacle penetration that would require a pilot to deviate from the VDA between MDA and touchdown, the VDA/TCH will be replaced with the note “Visual Segment- Obstacles” in the profile view of the IAP (See FIG 5−4−14). Accordingly, pilots are advised to carefully review approach procedures to identify where the optimum stabilized descent to landing can be initiated. Pilots that follow the previously published descent angle, provided by the RNAV system, below the MDA on procedures with this note may encounter obstacles in the visual segment. Pilots must visually avoid any obstacles below the MDA.
(a) VDA/TCH data is furnished by FAA on the official source document for publication on IAP charts and for coding in the navigation database unless, as noted previously, replaced by the note “Visual Segment – Obstacles.”
(b) Commercial chart providers and navigation systems may publish or calculate a VDA/TCH even when the FAA does not provide such data. Pilots
are cautioned that they are responsible for obstacle avoidance in the visual segment regardless of the presence or absence of a VDA/TCH and associated navigation system advisory vertical guidance.
2. The threshold crossing height (TCH) used to compute the descent angle is published with the VDA. The VDA and TCH information are charted on the profile view of the IAP following the fix (FAF/stepdown) used to compute the VDA. If no PA/APV IAP is established to the same runway, the VDA will be equal to or higher than the glide path angle of the VGSI installed on the same runway provided it is within instrument procedure criteria. A chart note will indicate if the VGSI is not coincident with the VDA. Pilots must be aware that the published VDA is for advisory information only and not to be considered instrument procedure derived vertical guidance. The VDA solely offers an aid to help pilots establish a continuous, stabilized descent during final approach.
3. Pilots may use the published angle and estimated/actual groundspeed to find a target rate of descent from the rate of descent table published in the back of the U.S. Terminal Procedures Publication. This rate of descent can be flown with the Vertical Velocity Indicator (VVI) in order to use the VDA as an aid to flying a stabilized descent. No special equipment is required.

 

[Palmpilot]

Between those varying FAA publications, it's no wonder pilots are confused!

 

[luvflyin]

And this current guidance in the AIM, 5−4−5. Instrument Approach Procedure (IAP) Charts:

Ok. There it is. If the Chart Maker rolls their own, it’s still a “VDA”

..…(b) Commercial chart providers and navigation systems may publish or calculate a VDA/TCH even when the FAA does not provide such data.….