TACA aircraft crashed in Honduras
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Originally Posted by bubbers44
No adjustment for a 1% downslope really surprises me
kwick, by any chance would you have the available forecast at the time the crew received its pre-flight briefing from dispatch ?
That document would tell us what was the possible plan for the arrival time according to wind and runway condition ?
Originally Posted by Lemurian
"LDA = Landing distance available : 1650 m
Baseline calculation : LW = 60 T ; RWY wet ; 5 kt tailwind : 1,352 m
(1110m + 10% altitude correction, 10.5% tailwind correction and -3% for operating reversers ).
According to these figures, the aircraft dispatch was legal.
Now I calculated the maximum allowable weight in these conditions and I found 68 T, quite a hefty margin, it seems.
It is now time to look into the influence of the 10 kt tailwind : a whopping 21 % ! and in this case a landing weight of 66 t was allowed.
Our landing distance at 60 t and 10 kt tailwind now comes to 1,472 m"
There is no correction for runway slope (which really surprised me ! ).
But now, out of the QRH, this is the in Flight performance for required runway length. still at 60T:
"In-Flight performance tables,
Considering an airport elevation of 3,300 ft and a wet runway. And a landing weight of 60 tons.
Base line : Landing runway length required : 1640 m
to which the following corrections apply :
Altitude : 3% per 1000 ft ---> 10%
Tailwind : 21%
Operating reversers : - 8%
Vapp = Vls : - 3%
Total correction : 20% ---> 328 m
So the *required runway length* for these conditions is 1640 + 328 = 1,968 m
Baseline calculation : LW = 60 T ; RWY wet ; 5 kt tailwind : 1,352 m
(1110m + 10% altitude correction, 10.5% tailwind correction and -3% for operating reversers ).
According to these figures, the aircraft dispatch was legal.
Now I calculated the maximum allowable weight in these conditions and I found 68 T, quite a hefty margin, it seems.
It is now time to look into the influence of the 10 kt tailwind : a whopping 21 % ! and in this case a landing weight of 66 t was allowed.
Our landing distance at 60 t and 10 kt tailwind now comes to 1,472 m"
There is no correction for runway slope (which really surprised me ! ).
But now, out of the QRH, this is the in Flight performance for required runway length. still at 60T:
"In-Flight performance tables,
Considering an airport elevation of 3,300 ft and a wet runway. And a landing weight of 60 tons.
Base line : Landing runway length required : 1640 m
to which the following corrections apply :
Altitude : 3% per 1000 ft ---> 10%
Tailwind : 21%
Operating reversers : - 8%
Vapp = Vls : - 3%
Total correction : 20% ---> 328 m
So the *required runway length* for these conditions is 1640 + 328 = 1,968 m
Would it be possible for you to attach the perf charts you're using ? (does not matter if they're not for V2500 engines)
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With the aircraft with the 1% downslope charts the landing distance that day was then 2,125 m. Available was 1640 m. Same airplane, different charts, right? I know we could not have attempted this landing in the B757. That is why I have been asking how can the A320 do it.
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Thank you Lemurian and CONF iture for the data. It makes more sense now. I loved flying into TGU and hope it opens up again to major airlines. It required paying attention to details. It wasn't for everybody but I loved it.
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To resume:
For a 320 at an estimated 60 tonnes landing weight on a WET Rwy 02
- In terms of dispatch Required Landing Distance zero wind was the limit.
- In terms of realisation Actual Landing Distance 10kt tailwind was still ... "attemptable" even with an 8% downhill penalty, but with virtually NO MARGIN !
Strongreslve rightfully made mention of the DAMP comment by ATC. That could have had an influence on the crew decision making as for Airbus, in terms of performance factor, DAMP is in the same category as DRY.
BUT, to me, that comment came very late in the Rwy02 approach process and the crew had probably already made its mind for a WET runway (?)
According to the video, that comment will be very much questionable …
bubbers44, what is the downhill correction for 757 ?
For a 320 at an estimated 60 tonnes landing weight on a WET Rwy 02
- In terms of dispatch Required Landing Distance zero wind was the limit.
- In terms of realisation Actual Landing Distance 10kt tailwind was still ... "attemptable" even with an 8% downhill penalty, but with virtually NO MARGIN !
Strongreslve rightfully made mention of the DAMP comment by ATC. That could have had an influence on the crew decision making as for Airbus, in terms of performance factor, DAMP is in the same category as DRY.
BUT, to me, that comment came very late in the Rwy02 approach process and the crew had probably already made its mind for a WET runway (?)
According to the video, that comment will be very much questionable …
bubbers44, what is the downhill correction for 757 ?
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My flight bag got underwater in hurricane Wilma so I have no access to any charts since I retired. Our 02 landing data was very conservative and had to have the 1% downslope included. The lowest number for runway length charts was exactly what 02 was from the displaced threshold. We couldn't throw in 5 knots for the children because then you could not land some days. My earlier post about the 25,000 pound advantage shows slope made a difference. 700 ft additional runway on 20 would not get you that much additional weight alone. We flew a safe approach into TGU using these charts and never had a problem. If Taca can justify landing under these conditions then TGU was unsafe. If they can't TGU was safe only if you followed company procedures.
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Something interesting, from El Heraldo newspaper:
http://www.heraldohn.com/ez/index.php/plain_site_user/ediciones/2008/06/14/la_pista_de_toncontin_no_fue_la_responsable
Toncontin runway was not responsible
International experts in the field of pavement find that asphalt is in optimal conditions and ruled out that it provoked the accident
In the article it mentions that Toncontin runway is O.K. They made various friction tests with a vehicle equipped with special equipment certified by the FAA that has additional tires and water pumps to simulate an aircraft landing on a wet runway for adherence. It was found that the runway is in optimum conditions and much better than some other runways in the area.
As always, hope the transcripts will provide some light at the end of the tunnel. It is dark yet, and I would like to reserve my comments on this runway report.
http://www.heraldohn.com/ez/index.php/plain_site_user/ediciones/2008/06/14/la_pista_de_toncontin_no_fue_la_responsable
Toncontin runway was not responsible
International experts in the field of pavement find that asphalt is in optimal conditions and ruled out that it provoked the accident
In the article it mentions that Toncontin runway is O.K. They made various friction tests with a vehicle equipped with special equipment certified by the FAA that has additional tires and water pumps to simulate an aircraft landing on a wet runway for adherence. It was found that the runway is in optimum conditions and much better than some other runways in the area.
As always, hope the transcripts will provide some light at the end of the tunnel. It is dark yet, and I would like to reserve my comments on this runway report.
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a little bit more about x-wind techniques for A320's
Dear RWA,
An extract from the A320's FCTM, complementing your info from the FCOM:
FLARE
The objectives of the lateral and directional control of the aircraft during the flare
are:
-- To land on the centerline
-- And, to minimize the loads on the main landing gear.
During the flare, rudder should be applied as required to align the aircraft with
the runway heading. Any tendency to drift downwind should be counteracted by
an appropriate input on the sidestick.
In the case of a very strong cross wind, the aircraft may be landed with a
residual drift (maximum 5°) to prevent an excessive bank (maximum 5°).
Consequently, combination of the partial de-crab and wing down techniques may
be required.
Just like any other aircraft...
Greetings!
An extract from the A320's FCTM, complementing your info from the FCOM:
FLARE
The objectives of the lateral and directional control of the aircraft during the flare
are:
-- To land on the centerline
-- And, to minimize the loads on the main landing gear.
During the flare, rudder should be applied as required to align the aircraft with
the runway heading. Any tendency to drift downwind should be counteracted by
an appropriate input on the sidestick.
In the case of a very strong cross wind, the aircraft may be landed with a
residual drift (maximum 5°) to prevent an excessive bank (maximum 5°).
Consequently, combination of the partial de-crab and wing down techniques may
be required.
Just like any other aircraft...
Greetings!
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Hi, rc330jj, welcome to the forum.
I've made no secret of the fact that most of my flying has been very much of the 'seat of the pants' variety. But please educate me as to how (at the critical flaring stage) I could make certain sure that I had only applied a maximum bank angle of 5 degrees? Especially in an A320, that provides no 'feedback' on the sidestick? And PLEASE don't say 'by looking at the indicator on the panel'.......... in my limited experience you simply can't afford to spend time doing that in the flare in any sort of difficult landing, and anyway there's a 'lag' in the instruments?
Not in any aeroplane that I've ever had the privilege of flying. In my own experience (admittedly limited) you apply as much bank and rudder as your eyes and ears and instincts and judgement (and your 'backside') 'tell' you to apply? You certainly don't have somehow to ensure that you don't exceed a bank angle of 5%?
Not, IMHO, in any properly-designed aeroplane, anyway.....
Originally Posted by rc330jj
In the case of a very strong cross wind, the aircraft may be landed with a residual drift (maximum 5°) to prevent an excessive bank (maximum 5°).
Originally Posted by rc330jj
Just like any other aircraft...
Not, IMHO, in any properly-designed aeroplane, anyway.....
Last edited by RWA; 14th Jun 2008 at 15:36.
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Toncontin airport can not let airliners land with 10 knot tailwinds on runway 02. It is unsafe as has been proven. If the charts for that 02 approach with 1 % downslope wet is correct they needed 500 more meters of runway. Why US carriers were restricted and Taca was not is a big question. I think Honduras must be embarassed not letting any commercial major airliners land there at their capital because their own airline had two incidents in the last 10 years and we haven't had any accidents. We can't land with tailwinds unless the runway is dry and never more than 5 knots.
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Hi RWA,
First of all, all I intended with the previous post was to demystify a little bit of what is widely said about the airbus' flight controls.
I believe your experience is right, at that stage of the flight(Flare),I do too just look outside and use the same "backside feel" that you do.To watch the instruments at that point,and make "Standard Calls" to alert you ,is a PNF duty.In any case,the limits that extract was "talking" about, regard strong crosswinds,that , according to another text from airbus, are x-winds in excess of 20 kt,i.e. pretty close to the aircraft limitation.
Note [Airbus recommended technique]:
During the flare, rudder should be applied as required to align the aircraft with the runway heading. Any tendency to roll downwind should be counteracted by an appropriate input on the sidestick (or control column, as applicable).
With higher crosswind (typically above 15 kt to 20 kt crosswind component), a safe crosswind landing requires:
A crabbed-approach, and
A partial decrab prior to touchdown, using a combination of bank angle and crab angle (achieved by applying cross-controls).
On most Airbus models, this requires touching down with:
Maximum 5 degrees of crab angle, and
Maximum 5 degrees of bank angle.
Cutting to the point, since I don't want to bore you guys with these details,I believe the airbus can be flown just like any other aircraft(At least I have always used these same flying techniques),respecting its published limits.
I believe that the problem resides on what Bubbers44(I couldn't agree more) pointed out in his last post:
Restrictions should be applied by operators and regulators in certain extreme conditions,mainly in critical airports(e.g.:no landing allowed on a short wet rwy with any tailwind).I guess ,IMHO, this was the main factor on the A320's accidents/incidents we've been talking about on this thread.A safety-minded Company policy and strict adherence to it can prevent the accidents, it's not about the aircraft type!
P.S. :sorry for the long post!
First of all, all I intended with the previous post was to demystify a little bit of what is widely said about the airbus' flight controls.
I believe your experience is right, at that stage of the flight(Flare),I do too just look outside and use the same "backside feel" that you do.To watch the instruments at that point,and make "Standard Calls" to alert you ,is a PNF duty.In any case,the limits that extract was "talking" about, regard strong crosswinds,that , according to another text from airbus, are x-winds in excess of 20 kt,i.e. pretty close to the aircraft limitation.
Note [Airbus recommended technique]:
During the flare, rudder should be applied as required to align the aircraft with the runway heading. Any tendency to roll downwind should be counteracted by an appropriate input on the sidestick (or control column, as applicable).
With higher crosswind (typically above 15 kt to 20 kt crosswind component), a safe crosswind landing requires:
A crabbed-approach, and
A partial decrab prior to touchdown, using a combination of bank angle and crab angle (achieved by applying cross-controls).
On most Airbus models, this requires touching down with:
Maximum 5 degrees of crab angle, and
Maximum 5 degrees of bank angle.
Cutting to the point, since I don't want to bore you guys with these details,I believe the airbus can be flown just like any other aircraft(At least I have always used these same flying techniques),respecting its published limits.
I believe that the problem resides on what Bubbers44(I couldn't agree more) pointed out in his last post:
Restrictions should be applied by operators and regulators in certain extreme conditions,mainly in critical airports(e.g.:no landing allowed on a short wet rwy with any tailwind).I guess ,IMHO, this was the main factor on the A320's accidents/incidents we've been talking about on this thread.A safety-minded Company policy and strict adherence to it can prevent the accidents, it's not about the aircraft type!
P.S. :sorry for the long post!
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This was extracted from the FAA, SAFO (Safety Alert for Operators) number 07007, dated 9/17/2007, applicable to Airbus 318, 319, 320, 321 series airplanes.
http://www.faa.gov/other_visit/aviation_industry/airline_operators/airline_safety/safo/all_safos/media/2007/SAFO07007.pdf
(recommended reading, maybe for discussion)
(recommended reading, maybe for discussion)
"Pilots should select an appropriate autobrake level for landing in accordance with operator-specific procedures".
Per bubbers44 last post, finally someone should be responsible if landing under some "non-normal" conditions was approved at any time. As we can see, and it reinforces the idea of not overruling or putting extreme pressure on the operator in such a way that the authority runs the business, the authorities leave some part of the homework to the operator, in order to develop procedures according to their organization and other matters (experience and safety included)
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RWA
But please educate me as to how (at the critical flaring stage) I could make certain sure that I had only applied a maximum bank angle of 5 degrees?
Seat-of-the-pants flying doesn't apply any more here.
Especially in an A320, that provides no 'feedback' on the sidestick? And PLEASE don't say 'by looking at the indicator on the panel'.
in my limited experience you simply can't afford to spend time doing that in the flare in any sort of difficult landing, and anyway there's a 'lag' in the instruments?
Face it, flying a jet has very little to do with visual cub piloting...We are as a matter of fact always on instruments at diverse degrees...we've replaced the *relative nose / horizon* position of the light aircraft with a more accurate re-construction of the outside world... Part of being a jet pilot, I would guess and actually, the PFD is always in our line of vision and scanning it is an acquired technique...A second nature.
You certainly don't have somehow to ensure that you don't exceed a bank angle of 5%?
Last edited by Lemurian; 17th Jun 2008 at 00:13.
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Here we can see an Airbus 319 doing a touch and go in Toncontin. Sure, it is hard to tell if it has passengers or cargo or nothing inside, but anyway it can do it, getting back in the air from the asphalt in that short runway.
http://www.youtube.com/watch?v=CRoms_Ivedk
http://www.youtube.com/watch?v=CRoms_Ivedk
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Why would anybody attempt a touch and go landing at TGU in an Airbus? They obviously planned it because the touchdown was right on the threshold. Maybe their attitude about this critical airport had something to do with the crash. If they practiced touch and go landings a 10 knot tailwind wet full stop landing should be a piece of cake.
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Lemurian,
Once again we disagree. RWA said on a difficult landing you don't have time to look at your panel for bank angle. I agree with him. I only glance at airspeed because bank angle is most accurate looking out the window. You only have so many brain cells to tell you what to do so I try not to waste any looking at secondary information that is already there. I have never looked at my panel once in landing to see what my bank angle was. No dinged wingtips or pods yet. I can't try your system because they made me retire at 60.
Once again we disagree. RWA said on a difficult landing you don't have time to look at your panel for bank angle. I agree with him. I only glance at airspeed because bank angle is most accurate looking out the window. You only have so many brain cells to tell you what to do so I try not to waste any looking at secondary information that is already there. I have never looked at my panel once in landing to see what my bank angle was. No dinged wingtips or pods yet. I can't try your system because they made me retire at 60.
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bubbers44,
It will be boring to see the day we'd agree on everything .
As I said, especially on a x-wind landing and places where you don't have a clear "horizon", a quick glance at your attitrude (how long does it take ? A blink ) to make sure your wings are level is the wise move.
On a 747 for instance, it's really important, as a wing flex on the always possible hard landing will get that outside engine pod that closer to the runway surface. The top of the instrument panel , again exception of a very few airplanes like the L-1011 are not a reliable reference.
Sorry that's how I've been flying, taught and practised...and I don't believe in seat-of-the-pants jet flying...on any airliner (and I've flown a few...)
On an other subject, the FCOM tables do not include runway slope...but the performance book for each airport, runway, obstacle, one-engine failure trajectory, etc... include all the data. The procedure is to ask for the print-out whether by fax from the station or via ACARS.
.As I said, especially on a x-wind landing and places where you don't have a clear "horizon", a quick glance at your attitrude (how long does it take ? A blink ) to make sure your wings are level is the wise move.
On a 747 for instance, it's really important, as a wing flex on the always possible hard landing will get that outside engine pod that closer to the runway surface. The top of the instrument panel , again exception of a very few airplanes like the L-1011 are not a reliable reference.
Sorry that's how I've been flying, taught and practised...and I don't believe in seat-of-the-pants jet flying...on any airliner (and I've flown a few...)
On an other subject, the FCOM tables do not include runway slope...but the performance book for each airport, runway, obstacle, one-engine failure trajectory, etc... include all the data. The procedure is to ask for the print-out whether by fax from the station or via ACARS.
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Originally Posted by Lemurian
You are confusing a lot of things here : your controls position, be they a yoke, a stick or an FBW sidestick will not give you ANY indication on your aircraft attitude : it will come only from a glance at your PFD.
But as far as I know, there is a pretty fundamental difference between Airbuses and any other sort of aeroplane.
Describing in words how you fly an aeroplane is notoriously difficult. It's like trying to describe in words how you ride a bicycle. But in the sort of aircraft I was used to, to bank slightly into wind, I'd have applied pressure to the yoke (mere 'stick' sometimes) and also a touch of opposite rudder until my eyes - and the seat of my pants - told me that I'd managed to eliminate all or most of any drift.
Then I'd have increased or decreased the pressure on the controls as necessary to hold that attitude and direction as accurately as I possibly could until I heard that lovely rumbling sound.....ideally achieving one of those (for me. rarer than I'd have liked
) landings with no bounce at all. Or a nice continuous reassuring 'scrape and bump' if I happened to be flying a sailplane... As I understand the Airbus systems, moving the sidestick commands not a control surface position but a 'roll rate.' So, flying one of those, I'd have had to learn a totally-different technique. As far as I know, from reading, it's necessary to 'bump in' some bank, and then centre the sidestick. If that's enough, fine - but if it's NOT enough, I'd have to 'bump' the stick a bit more. If it's too much, I'd have to 'bump' the stick a bit in the opposite direction, to reduce the commanded 'roll rate.'
As to the risk of 'engine strike,' that possibility had occurred to me. But I concluded that, if a mere 5 degrees of bank was enough to cause an engine strike, all Airbuses would be spending more time in the hangar getting engine changes than they did in service. There HAS to be another reason for the 5-degree limit......
And, as Bubbers44 said, my priority when landing was ALWAYS airspeed. Especially when gliding. In my experience (right or wrong) the wrong airspeed (either way) is more 'life-threatening' than attitude will ever be.
OK - 'Fire when ready.' But please don't just keep saying that I'm 'getting it wrong.' I admit that I'm almost certainly 'getting it wrong' - some of it, at the least. But that's why I'm asking the people who actually do the job......
Last edited by RWA; 17th Jun 2008 at 13:08.
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This may have been posted already; but if not, it will give you an idea of what the approach into TGU entails.
http://www.youtube.com/watch?v=v_z5HtME9n8
http://www.youtube.com/watch?v=4QNb8x1_vKc
1) American 757
2) Continental 737
http://www.youtube.com/watch?v=v_z5HtME9n8
http://www.youtube.com/watch?v=4QNb8x1_vKc
1) American 757
2) Continental 737