Turkish A330 incident, Kathmandu

[FlightDetent]

Aterpster: until now I considered APVs to be a subset of non-precision approaches, as "electronic guidance in vertical plane" is not available so they cannot be PApchs. You repeatedly say something different and do not sound like a man who's not sure. Where do baroAPVs fit then?

regards, FD

PS: Ha, got it!

[Capn Bloggs]

Forget the concepts of "Non-Precision" and "Precision". Because there are now approaches that are flown "similar" to an ILS eg LPV, GLS, Baro VNAV, RNP-AR ie they give proper, legalised vertical commands which you must follow (like you follow a GS), the old "precision" concept ie provision of a GlideSlope, has become muddied. That's why the system introduced 2D (2 dimensional, the old MDA-type approaches) and 3D (approaches flown with vertical guidance/commands ie 3 dimensional that include ILS and RNP-AR and indeed BaroVNAV. All 3D approaches are the same: follow the pitch commands down to the DA and then go around if not Visual.

FD, an "APV" is an APproach with Vertical Guidance", a 3D approach. Flown exactly like an ILS, but obviously not one, in the historical sense of the "precision" concept. The "BARO" part signifies the altimeter/QNH is being used to provide vertical commands, as opposed to a GLS, where I assume the GPS gear is used to provide the "glidepath" to follow. An RNP-AR would therefore be a type of Baro-VNAV, I suppose, which is of course an APV!

[aterpster]

Bloggs:

Forget the concepts of "Non-Precision" and "Precision". Because there are now approaches that are flown "similar" to an ILS eg LPV, GLS, Baro VNAV, RNP-AR ie they give proper, legalised vertical commands which you must follow (like you follow a GS), the old "precision" concept ie provision of a GlideSlope, has become muddied. That's why the system introduced 2D (2 dimensional, the old MDA-type approaches) and 3D (approaches flown with vertical guidance/commands ie 3 dimensional that include ILS and RNP-AR and indeed BaroVNAV. All 3D approaches are the same: follow the pitch commands down to the DA and then go around if not Visual.

FD, an "APV" is an APproach with Vertical Guidance", a 3D approach. Flown exactly like an ILS, but obviously not one, in the historical sense of the "precision" concept. The "BARO" part signifies the altimeter/QNH is being used to provide vertical commands, as opposed to a GLS, where I assume the GPS gear is used to provide the "glidepath" to follow. An RNP-AR would therefore be a type of Baro-VNAV, I suppose, which is of course an APV!

Good summary!

Having said that I think ICAO is full of it on LPV. It walks and quacks just like a CAT I ILS except LPV is always rock solid unlike some ILS facilities.

Further, the fact that the U.S. (perhaps other countries with SBAS as well) use the exact same obstacle clearance surfaces and lateral dimensions as used for CAT I ILS says legions.

[PENKO]

Thanks for the info gentlemen. To further simplify things, we fly all non-precision approaches as APV approaches to a DA. So even an NDB approach will have a DA in our charts. GPS or no GPS.

[peekay4]

To further simplify things, we fly all non-precision approaches as APV approaches to a DA.

Mmm... depending on the jurisdiction there may be legal differences between flying NPA using CDFA to a DDA, vs. flying an APV to a DA. They are not exactly equivalent, even if the procedures may be similar.

E.g., in most jurisdictions, when executing a go around you may go below the APV DA, but for an NPA you must ensure your DDA has sufficient buffer (usually 50 ft) to not go below the MDA.

[sarge75]

Criminal decision not to go around.

Criminal that it took 10 minutes to evacuate the plane.

Criminal that the airport was open. That said, to quote a CAAN official, "it doesn't matter because we are already on the black list"

[FlightDetent]

Originally Posted by peekay4

E.g., in most jurisdictions, when executing a go around you may go below the APV DA, but for an NPA you must ensure your DDA has sufficient buffer (usually 50 ft) to not go below the MDA.

Just for the record, EASA is not in the MOST bucket.

FD.

[No Fly Zone]

Quiet Observation; No More

Please recall that I am NOT an expert with these types of approaches. In this case I read darn near everything in the hope of learning something, but I'm left hanging, wondering what happened to the common sense and basic safety that most apply to their flying? In short, when one reaches DA and ALL safe landing requirements are not met, Why the Heck not Go Around? Unless the airplane is already running on vapors, why not? Even prior, if the known conditions were that bad, why had the trip not already diverted elsewhere? A possible exception might include equally poor conditions at a diversion field and yes, the regions choices are limited. Still, responsible crews carry additional fuel for those events, do they not? Back to the principal landing attempt: unless the airplane was known to be on fire or in some other critical state, why the heck not Go Around and give the PF another chance to reach DA with everything properly aligned and aimed, including RWY alignment? Unless there are very good reasons for not doing so, how can this be called anything other than Very Poor Flying? Did I miss some critical piece of this puzzle? I'm not pointing fingers, but I am asking. Thanks.

[IcePack]

No Fly Zone, what you say is correct. However in the real world you do not know how behind locked doors the company react to go arounds or failure to "get in" even in responsible airlines they apply pressures. For instance if you divert to alternate I know some airlines will ask why you did not hang about & then declare a mayday when down to final reserv. Am not saying in this case anything like this happened but we do not know what pressures the crew were under in reality or what pressure they perceived.

[aterpster]

IcePack:

No Fly Zone, what you say is correct. However in the real world you do not know how behind locked doors the company react to go arounds or failure to "get in" even in responsible airlines they apply pressures. For instance if you divert to alternate I know some airlines will ask why you did not hang about & then declare a mayday when down to final reserv. Am not saying in this case anything like this happened but we do not know what pressures the crew were under in reality or what pressure they perceived.

The accident occurred on the second approach attempt. The first approach was correctly flown into a missed approach because of inadequate visual references. It is quite a "cross county" flight through the missed approach to the missed approach holding point, then back onto the MANRI RNP STAR to RATAN, then eventually back onto the approach procedure. From the MAP through the entire circuit back to the MAP again is 127.9 nautical miles. Plus there is the hold at the MAPh. All of this is probably flown at an average ground speed of 210-250 knots. Much of the approach path is restricted to a maximum of 170 KIAS.

So, there was time for the weather to get better, which is typical at VNKT as the morning progresses. But, it did not this particular morning. Also, at some point in the first missed approach, probably holding at the MAPh, a flight attendant was on the flight deck and advised the captain, "If they diverted to Delhi there would be a big burden." (approach chart in Post #22.)

[spin_doctor]

The report made interesting reading and does not reflect particularly well on anyone.

I would agree that the primary cause of the accident was the decision to continue below DA with no visual reference (although the crew appear to state that they did have visual reference but this is not backed up by either their actions or the CVR).

What stopped them from 'getting away with it' this time was the addition of incorrect data (offset threshold position) which meant they were not aligned with the runway centreline.

One of the recommendations in the report is for the operator to implement a process for validation of the nav database. This is particularly worrying since the approach was an RNP AR APCH. Approval to operate this type of procedure requires extra processes to be in place and approved by the regulator, one of which is a requirement to validate each and every version of the nav database, if necessary by flying the approaches in the sim (or VFR) prior to operational use. The fact that this process is recommended by the report suggests that this was not being done here, which means the operator should never have been approved for RNP AR as they do not meet the requirements.

[ATC Watcher]

Spin doctor :

the operator should never have been approved for RNP AR as they do not meet the requirements.

Correct , and from what I have heard , it is not only the operator that did not meet the AR requirements .

What would be interesting to know is the reaction of the insurers, a brand new 330 is not cheap.

[aterpster]

Spin Doctor:

One of the recommendations in the report is for the operator to implement a process for validation of the nav database. This is particularly worrying since the approach was an RNP AR APCH.

Add the Nepal aviation authority to that list. A flight inspection was required. That did not happen nor was it discussed in the report.

Approval to operate this type of procedure requires extra processes to be in place and approved by the regulator, one of which is a requirement to validate each and every version of the nav database, if necessary by flying the approaches in the sim (or VFR) prior to operational use. The fact that this process is recommended by the report suggests that this was not being done here, which means the operator should never have been approved for RNP AR as they do not meet the requirements.

Agree in this case. But, if an RNP approach has not been changed, only the database needs to be verified, the "flyability" of the unchanged approaches need not be accomplished.

Also, Nepal's design is defective in that the MAP is at the threshold rather than the DA point. That is non-compliant with PANS-OPS. Nothing mentioned about that in the accident report, either.

THY and Nepal are akin to Frick and Frack.

[firstchoice7e7]

Will the A330 involved in this crash be repaired?

Nice pic in the following report

https://thehimalayantimes.com/nepal/...crash-landing/

[readywhenreaching]

repair ? looks like its being parted out. smells like a hull loss.