Air Canada Rouge EGPWS warning at Huatulco

[confusedalot]

Yes of course, that would be the obvious course of action in a non radar environment, which is why I still think something is still missing in this particular writeup/event. One of those he said she said affairs where confusion was paramount?

[Eric Janson]

I think some of you may be missing the following:-

Air traffic control cleared the flight to descend to 6000 feet MSL at pilot's discretion.

Perfectly normal to get this kind of clearance.

[BBQ Chips]

I have flown into Huatulco many times. Once as a brand new FO my Captain interpreted exactly this clearance in exactly the same way while we were IMC. I quickly corrected them and we landed without incident (not saying I am a super pilot, just illustrating how easily and quickly the clearance can be confused based on 2 words). A thick Mexican accent never helps things either. Perhaps a better clearance would be “cleared 6000 feet with your own terrain “

[mbav8r]

Have not flown into Mexico but a question that comes to mind, are the terms “radar identified and radar services terminated” in use?
Perhaps the crew thought they were identified.

[monkey]

The descent into HUX is made in Non Radar environment. Like all of Central America, Mexico, you are on your own for terrain. Cleared for the approach doesn't mean you can just automatically descend down to whatever altitude you want to, you still need to respect minimum safe altitudes. In this case from NUDOS, the reference for safe altitude is the airway MEA, then the 25 NM sector altitude from the chart. The highest peak is essentially directly on the airway, if you descend down from NUDOS it won't take long to get to the same altitude as the ridge line.

Pretty serious lack of situation awareness, they are very lucky not to have had a hull loss.

[hst]

Something is missing in this picture.

I’d agree. A healthy dose of S.A!

Having operated into this airport many times in the past (C3,SSV days) this place along with OAX, MZO, PVR etc should make one extra vigilant with respect to terrain and procedural IFR clearances.

[CpnCrunch]

Cleared for the approach doesn't mean you can just automatically descend down to whatever altitude you want to, you still need to respect minimum safe altitudes.

But they weren't just "cleared for the approach". They were cleared to descend to 6000ft at their discretion. I don't think this could happen in Canada, as ATC is prohibited from issuing clearances below the minimum IFR altitude unless within radar airspace.

http://www.navcanada.ca/EN/products-and ... 19.pdf#top

Isn't "descend at your discretion" normally reserved for VFR, at least in Canada? And doesn't ICAO regulate this phraseology?

[kevenv]

I don't think this could happen in Canada, as ATC is prohibited from issuing clearances below the minimum IFR altitude unless being radar vectored.

http://www.navcanada.ca/EN/products-and ... 19.pdf#top

That's not what your attachment says at all.

"Within air traffic service (ATS) surveillance coverage, it is common for controllers to issue the minimum
vectoring altitude (MVA) when issuing direct routes. An MVA can be lower than a published minimum IFR
altitude (minimum sector altitude [MSA], minimum obstacle clearance altitude [MOCA], MEA, or area
minimum altitude [AMA])."

For our purposes the MVA is an appropriate minimum ifr altitude. No need to be on vectors for us to use it.

[CpnCrunch]

Sorry, I meant within radar coverage, which is what the PDF says. I've edited my original comment.

In this case they were in a non-radar envionment.

[confusedalot]

But, but, but, on the Air Canada OTS thread, it has been declared that Air Canada only hires the faultless best.....and those who are not offered a position are substandard.

Sorry for the sarcasm, one of my chief character faults. Yeah, this is looking like a rather blatant situational awareness problem.

Just waiting for an AC shill to hijack the thread.

[pelmet]

Just waiting for an AC shill to hijack the thread.

They seem to have mysteriously disappeared. I'll fill in.....No one hurt, on time....good job.

[confusedalot]

absolutely, thank god the egpws did a good job and nobody got hurt.

[Gilles Hudicourt]

Oh and one more thing, every single airplane driver in this world knows that there is such a thing a minimum radar vectoring altitudes that the controller knows at any given place but you may perhaps not, since they are not published on jepps. So clearing an airplane to 6000 feet east of Hualtuco does not make sense, knowing the cumulogranites that just so happen to permanently be there.

So...are you going to question the controller on his minimum radar vectoring altitude in comfy yyz? You better have a good answer for that if you do.

Which brings me to my first point; something is missing in this picture, nothing more.

Except that this was a non radar environment. Like in Canada in such a case, the pilots are responsible for terrain clearance......
Minimum Altitudes to Ensure Obstacle Clearance

602.124 (1) Subject to subsections (2) and (3), the pilot-in-command of an IFR aircraft shall, except when taking off or landing, or when being radar-vectored by an
air traffic control unit, ensure that the aircraft is operated at or above
(a) the MOCA, when the aircraft is on an airway or air route; and
(b) the minimum altitude established by the Minister to ensure obstacle clearance and specified on an IFR chart, when the aircraft is within airspace in respect of which such a minimum altitude has been established.

[confusedalot]

I think you are missing the point. We all know the rules, we all know not to fly into terrain, we all know, by reading the report comfy at our computers, that they were in a non radar environment.

Question is, did they realize that? If they did, and knowing the rules like everybody does, why did they do what they did?

Back to the situational awareness issue. Anyways, it's been debated to death.

[RFN]

Just flew into HUX the other day; my second time there ever, and my first in over 4 years. It was about a 6-7k ft ceiling over the mountains and basically SKC over the water.

The controllers are very clear, "Thick Mexican Accents" and all, that you are now radar service terminated. And even if you were still getting vectors, 6000ft is a long way from 14000. wow.
Its a good thing that controllers in other countries around the world don't have strong accents. Or terrain.

HUX is terrain critical, but it is by no means a complicated airport at all. The charts are painfully clear, even to a Non-AC driver. If you can get a reroute from Mexico City to the Oaxaca VOR and down to the HUX, that airway gets you in the lower 25 mile sector West of the 338 radial (i think... chart isn't in front of me), to 11400. If still IMC, crossing the VOR at 11400, and say 200kts with some flap makes it very simple and easy to descend on the teardrop to land on 25.

This incident is exactly why EGPWS (and the Escape Maneuver) exist so yay it did ITS job.

[daedalusx]

This incident is exactly why EGPWS (and the Escape Maneuver) exist so yay it did ITS job.

EGPWS can be MEL-ed ... what would have happened then ? Yay luck did ITS job ?!

[complexintentions]

Actually if the EGPWS had been MEL'ed that day it's equally possible they would have been more vigilant about checking their min safe altitudes.

[rookiepilot]

This incident is exactly why EGPWS (and the Escape Maneuver) exist so yay it did ITS job.

EGPWS can be MEL-ed ... what would have happened then ? Yay luck did ITS job ?!

.

[rookiepilot]

Cleared for the approach doesn't mean you can just automatically descend down to whatever altitude you want to, you still need to respect minimum safe altitudes.

But they weren't just "cleared for the approach". They were cleared to descend to 6000ft at their discretion. I don't think this could happen in Canada, as ATC is prohibited from issuing clearances below the minimum IFR altitude unless within radar airspace.

I assume you are excluding "cleared for AN approach" -- like in N Ontario Uc Airports in that ATC prohibition.

[pelmet]

Actually if the EGPWS had been MEL'ed that day it's equally possible they would have been more vigilant about checking their min safe altitudes.

And it is possible they would not.

Perhaps some only are more vigilant when the EGPWS is MEL'd as is implied by the above statement. Of course, if it is inop for a reason....such as, it was not working on the flight prior it being MEL'd, then perhaps, unknown to the crew, it was inop during a previous flight. One should not base their increased vigilance on the hope of the GPWS system's operability.

Plus, one should not be relying on it in the first place as it may have bad information. EGPWS is not just terrain, it is obstacles(option) as well but obstacles change, meaning the database needs to be changed. Airlines have a history of not having the database up to date.

I can't copy from this PDF file but on page 19 is an example of a EGPWS equipped aircraft crashing with no EGPWS alert.
https://flightsafety.org/wp-content/upl ... p18-20.pdf