Airbus Within 6ft of the Ground nearly 1 mile Short of Runway

[ATC Watcher]

At the very least, speak English to all, as the Germans ..., do.
Well wrong example, German is also used in all Regional airports , But your point about the fact that nationalism has no place in Aviation is fully correct but it goes both ways.

As to the Mentour Pilot video, excellent as usual ..Thanks for posting it.

[RudderTrimZero]

Yesterday I flew across France, due to no other reason than a very thick French accent spoken at Speed c, 3 pilots misheard the next frequency, read it back wrong AND were not corrected by French ATC. This is an increasingly common occurence.

[Nil by mouth]

As to the Mentour Pilot video, excellent as usual ..Thanks for posting it.

Petter Hörnfeldt does indeed make very interesting and informative videos. I wonder if he gleans any information from this forum? The QNH comments were like dëjà vu ;)

[ATC Watcher]

Well I am sure he looks in here too , but he mentions a few facts in his video that were not in the BEA report and were not here on PPRuNe either, so he must have good outside sources, but with 850.000 subscribers on his you tube videos and 12.000 members on his forum I guess he has an advantage over us in getting reliable and correct info.
For instance there is a small hint in this video that he knows exactly who the pilots were , we will see when the final report comes out if he was right.

[India Four Two]

I've been following Mentour Pilot for a couple of years. That was without doubt his best video to date. Very informative - even a non-pilot would understand what happened.

[Bbtengineer]

What a sad state of affairs that we still rely on VHF audio transmission of barometric pressure to determine altitude.

Why do we have to input it? Why do we have to cross check it? Is that really the best we can do?

The comments on language astound me.

Repeated assertions that language isn’t code fly in the face of the facts here.

This was a standard transmission of standard information in a standard format.

It absolutely is code and as somebody above said it doesn’t matter the language it could be in Klingon.

It would be more accessible and we would be less likely to get it wrong if we used the same language all day, every day.

[Uplinker]

Not quite sure what point(s) you are making?

Transmission of QNH by voice is no more primitive than transmission of cleared altitude or heading or speed by voice.

Yes, in theory it could all be done by digital data transmissions, where the cockpit QNH setting simply updates in real time. (Ditto cleared levels, headings and speeds). But we all know that such a system would not be infallible either, and even more cross-checking would be required.

Altitude could be defined by GPS instead of barometric pressure, but like-wise, that would bring other potential problems and traps.

The thing is, we already have a pretty good system for air traffic control and altitude definition. Not infallible either, but very well tested and practised - we all know what to do and how to do it. PM listens to the latest meteorological report and writes it down, including the QNH. When ATC clears the aircraft to an altitude, the QNH is cross-checked with that independently achieved information.

What is starting to happen, I think, is that training is being slimmed down and skies are getting busier, duties are getting longer, and human performance and CRM is suffering, (and not just pilots). The PM in this incident does appear to hesitate on his read-back at one point, so I think he must have suspected that there was a mistake somewhere. But for whatever reason, it was not queried or followed up.

Having instructions transmitted in two languages instead of one, (at a very complicated and busy international airport, no less), prevented all pilots from hearing the QNH given repeatedly to other aircraft, which would have flagged up the error.

[Bbtengineer]

Not quite sure what point(s) you are making?

Transmission of QNH by voice is no more primitive than transmission of cleared altitude or heading or speed by voice.

Yes, in theory it could all be done by digital data transmissions, where the cockpit QNH setting simply updates in real time. (Ditto cleared levels, headings and speeds). But we all know that such a system would not be infallible either, and even more cross-checking would be required.

Altitude could be defined by GPS instead of barometric pressure, but like-wise, that would bring other potential problems and traps.

The thing is, we already have a pretty good system for air traffic control and altitude definition. Not infallible either, but very well tested and practised - we all know what to do and how to do it. PM listens to the latest meteorological report and writes it down, including the QNH. When ATC clears the aircraft to an altitude, the QNH is cross-checked with that independently achieved information.

What is starting to happen, I think, is that training is being slimmed down and skies are getting busier, duties are getting longer, and human performance and CRM is suffering, (and not just pilots). The PM in this incident does appear to hesitate on his read-back at one point, so I think he must have suspected that there was a mistake somewhere. But for whatever reason, it was not queried or followed up.

Having instructions transmitted in two languages instead of one, (at a very complicated and busy international airport, no less), prevented all pilots from hearing the QNH given repeatedly to other aircraft, which would have flagged up the error.

My points were two fold one of which I think we agree and one of which I am not sure.

1) I cannot see a reason why we don’t use GPS to cross check the results of QNH.

2) There is no reason to be delivering routine pressure information in two languages.

I am particularly perplexed by point two. A commenter above mentions repeatedly that we need to convey this information in native language.

I can’t see why.

Anyone who can learn to direct or fly a commercial aircraft can learn to deliver or receive this information in English.

We should reserve native language for non-standard scenarios.

This wasn’t one.

[Uplinker]

Yes, any international airport - especially a large and very busy airport - should use a single language for all ATC communications for solid safety reasons.

CDG has already been the site of a fatality when the wing of an aircraft - cleared to take off in French - killed an English speaking pilot of another aircraft - a situation that could have been realised and prevented had a single language been in operation.

It is madness to allow two languages to control such a high density and busy airport.

As to your point 1, yes, in theory, but as you know; GPS is not infallible either and can be jammed etc. Where is the GPS altitude read-out? is it on the PFD or on a page somewhere in the MCDU? We already have a well practised method to check and cross-check the QNH, and three independent pressure sensing altitude read-outs in the cockpit to cross check between, as well as the ATIS.

The mistake in this case was a mis-translation by ATC of the QNH from one language to another, and the aircraft in question either not following the standard QNH cross-check or not querying it.

[MechEngr]

The main problem is that QNH measures relative altitude and GPS measures absolute altitude, so the comparison really should be between the rad altimeter and the GPS, but over uneven terrain that rad alt reading isn't going to be so helpful unless the plane has a detailed terrain map to convert the latitude and longitude into an expected distance reading. The one place that QNH and GPS would coincide is on the runway, but then it's too late for circumstances like this.

To be more clear - the difference in altitude detected by the barometric system is dependent on the density of the air, so the comparison is inexact, but it won't matter as the control is based on eventually matching the pressure reported for the runway and the pressure detected by the barometric system. In the air the difference in pressure is a measure of the relative pressure altitude, not the absolute actual difference.

[DaveReidUK]

and GPS measures absolute altitude

Doesn't GPS actually measure relative, rather than absolute, altitude - that's to say relative to a reference ellipsoid that approximates the earth's surface ?

[tdracer]

Doesn't GPS actually measure relative, rather than absolute, altitude - that's to say relative to a reference ellipsoid that approximates the earth's surface ?
I can't speak for specific applications, but I have a GPS tracker system that I use in my high power rocketry. When I power it up, it reads that altitude of the launch site relative to MSL. There is a button that I then push that resets that altitude to zero so that subsequent readings are relative to the altitude of the launch site. The GPS can then be used to determine things like max altitude of the flight (and speeds - although during the ascent the speeds change to rapidly that the update rate of the GPS makes it less than completely useful).
As MechEngr notes, if that's how the system normally works, it would require a pretty detailed terrain map to reliably determine altitude to the local ground level.

[FlightDetent]

if that's how the system normally works, it would require a pretty detailed terrain map to reliably determine altitude to the local ground level.In which case all that needs to be done is align the GPS '0' to the same reference zero that has been in use since forever to calculate elevations and altitudes for the standard old-school aviation data-set? Within the original scope of the thread - not it's the altitude which was wrong already, no need to evaluate height.

My personal favourite is to mandate the ANSPs to publish radio-height at the 1000' AAL checkpoint for every IAP. Darn easy, GPWS, EGPWS and ACAS also started mandatory for big aeroplanes only. I mean, if the issue is flying into terrain and RAs exist, why insist on devising another tool or gadget instead of learning how to utilize the full potential of what we already have?

For the aeroplane discussed, an electronic comparison cross-check between FCU BARO REF and MCDU APPR PG seems a no-brainer.

[MechEngr]

Doesn't GPS actually measure relative, rather than absolute, altitude - that's to say relative to a reference ellipsoid that approximates the earth's surface ?

I think there are several datums that are available for reporting, including the GPS default ellipsoid WGS-84 (apparently), but a GPS nav unit is initially calculating a 3D position based on the orbits of the GPS satellite constellation. The report should be consistent for a consistent location, such as a if one is on a radio tower or mountain peak. The pressure altitude will vary and the difference with some other fixed location will vary for those fixed locations.

The more I look at it the more I don't want to look at it. https://geodesy.noaa.gov/GEOID/index.shtml It starts to glaze over the brain when considering that we live on a lumpy blob that is changing shape in ways that are measurable, but not reliably so from any location on the planet. Worse, where the satellites are is affected by the lumpy gravity of that lumpy blob. Gah!

There appears to be a project to convert to using the constellation directly as the reference; there is also a project to generate and equi-potential (they call it orthometric) model that includes differences in local gravity that is very useful in predicting water flow and flood plains. https://geodesy.noaa.gov/GRAV-D/pubs/GRAV-D_v2007_12_19.pdf

[fronzee]

I used that video in my Air Cadet radio class yesterday and the 12-14 year old cadets immediately picked up the mistake!
Easy when you know what to look for :)

[punkalouver]

I've been following Mentour Pilot for a couple of years. That was without doubt his best video to date. Very informative - even a non-pilot would understand what happened.

While I found the video from Mentour Pilot to be useful, it has left me wondering if his videos sometimes don't include important information such as this quote from post #4 on this thread: "9 seconds between minima and TOGA". Isn't that of significant importance.

[slast]

While I found the video from Mentour Pilot to be useful, it has left me wondering if his videos sometimes don't include important information such as this quote from post #4 on this thread: "9 seconds between minima and TOGA". Isn't that of significant importance.
To repeat - slightly edited - my earlier comment (post #133).
"the preliminary report seems to be clear that ...the crew flew straight through (what they believed to be) the MDA at a constant descent rate of 12 ft/sec, without having any visual references. It appears that the need for a go-around was not manifested for a further 6 seconds (72 ft further descent), when the Captain disconnected the autopilot and made a nose-up input, but a full go-around was not initiated for a further 3 seconds when TOGA was applied. So even if the altimeters had been set correctly obstacle clearance would have been significantly infringed – at the lowest point the aircraft would have been 123 feet below the correct MDA, apparently in full IMC. From the Captain’s actions (autopilot disconnect and stick back and then TOGA power 3 seconds later) it seems likely that he was not mentally prepared for a go-around.

So regardless of the altimetry issue, we have a prima facie serious breach of AOM in that the aircraft descended far below the indicated MDA without the Captain having seen visual cues which should already have “been in view for sufficient time for the pilot to have made an assessment of the aircraft position and rate of change of position in relation to the desired flight path.” (ICAO definition of reqjired visual reference)."
To repeat: it's "DECISION to land or go around height/altitude", not "start looking for cues altitude".