EK 231 20 December DXB IAD near crash?
Only half a speed-brake
For recording and display purposes, different from the source ADS-B transmission, FR24 nullifies some of the altitude data.
When an aircraft is geometrically below the 1013.25 isobaric surface, FR24 presentation would need to show negative values since ADS-B transmits level referenced to standard pressure.
Perhaps to avoid confusing the common inernaut, all sub-zero readouts are truncated. When our ilk try to convert ADS-B indicated FL back to ALT, that data is missing.
The cutoff layer is
FL < 0, which is the same as
ALT < (QNH - 1013.25)x27
The modest local 1018 hPa at occurrence time means displayed 0 by FR24 can be any ALT below 125 ft. (XPDR codes in 25 ft increments). Down to ELEV, that is
.
When an aircraft is geometrically below the 1013.25 isobaric surface, FR24 presentation would need to show negative values since ADS-B transmits level referenced to standard pressure.
Perhaps to avoid confusing the common inernaut, all sub-zero readouts are truncated. When our ilk try to convert ADS-B indicated FL back to ALT, that data is missing.
The cutoff layer is
FL < 0, which is the same as
ALT < (QNH - 1013.25)x27
The modest local 1018 hPa at occurrence time means displayed 0 by FR24 can be any ALT below 125 ft. (XPDR codes in 25 ft increments). Down to ELEV, that is
.Last edited by FlightDetent; 20th Feb 2022 at 10:22.
Originally Posted by FlightDetent
Yes, error is not a good naming.
For recording and display purposes, different from the source ADS-B transmission, FR24 nullifies some of the altitude data.
When an aircraft is geometrically below the 1013.25 isobaric surface, the FR24 presentation would need to show negative values, since ADS-B transmits altitude referenced to standard pressure which actually is a negative numeber in that case.
To avoid confusion for the common inernaut, all negative reports are truncted to 0 for FRIf FL < 0 then, for display their records.
When converting the ADS-B FL as reported FR24 to ALT, some of that data are simply not there.
The cutoff layer is
FL < 0, which is the same as
ALT < (QNH - 1013.25)x27
With the modest 1018 hPa at local station in the discussed case, where 0 is dispalyed by FR24 the ALT was (anything) less than 125 ft. (XPDR codes level in 25 ft increments).
For recording and display purposes, different from the source ADS-B transmission, FR24 nullifies some of the altitude data.
When an aircraft is geometrically below the 1013.25 isobaric surface, the FR24 presentation would need to show negative values, since ADS-B transmits altitude referenced to standard pressure which actually is a negative numeber in that case.
To avoid confusion for the common inernaut, all negative reports are truncted to 0 for FRIf FL < 0 then, for display their records.
When converting the ADS-B FL as reported FR24 to ALT, some of that data are simply not there.
The cutoff layer is
FL < 0, which is the same as
ALT < (QNH - 1013.25)x27
With the modest 1018 hPa at local station in the discussed case, where 0 is dispalyed by FR24 the ALT was (anything) less than 125 ft. (XPDR codes level in 25 ft increments).
Join Date: Oct 2002
Location: aaa
Posts: 240
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by DaveReidUK
OK, I think I see what you mean, although I'm still struggling to understand what a "gross error check" would prove, other than the existence of the FR24 QNH issue that I previously referred to.
Yes, that's more easily ascertained from the FR24 data as it's not QNH-dependent. At the quoted lift off time of 23:10:29 (per the report) the ADS-B data shows the 777 roughly abeam twy N4.
Yes, that's more easily ascertained from the FR24 data as it's not QNH-dependent. At the quoted lift off time of 23:10:29 (per the report) the ADS-B data shows the 777 roughly abeam twy N4.
But from reading more posts, from people such as yourself, who obviously know much more than me about FR24 data. It seems that the FR24 data is always wrong in high QNH conditions.
Therefor as you say the gross error check is redundant, if we already know its not reliable
Only half a speed-brake
Originally Posted by DaveReidUK
Good explanation of an often (as we have seen) misunderstood FR24 idiosyncrasy.
Join Date: Jul 2006
Location: Somewhere over the rainbow
Posts: 923
Likes: 0
Received 0 Likes
on
0 Posts
Talking about Flight Radar, why do they show the scheduled time as airborne time when the scheduled time shown on Flight Radar in my outfit at least is supposed to be the off block time?
Thank you.
Thank you.
Originally Posted by pineteam
Talking about Flight Radar, why do they show the scheduled time as airborne time when the scheduled time shown on Flight Radar in my outfit at least is supposed to be the off block time?
Join Date: Jul 2006
Location: Somewhere over the rainbow
Posts: 923
Likes: 0
Received 0 Likes
on
0 Posts
This flight for example: They showed the schedule time as 15h45. This is the STD: Time we suppose to push back. However they show the actual time as 16h25 which is the airborne time. I checked on the company system this flight actually pushed back at 16h09.
Originally Posted by pineteam
This flight for example: They showed the schedule time as 15h45. This is the STD: Time we suppose to push back. However they show the actual time as 16h25 which is the airborne time. I checked on the company system this flight actually pushed back at 16h09.
FR24 attempts to identify, as you have noted, the time the aircraft gets airborne - that's what appears in the "ATD" column. Whether that satisfies most people's understanding of an ATD is a moot point, but that's what they use.
Join Date: Jan 2008
Location: Netherlands
Age: 45
Posts: 286
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by DaveReidUK
Whether that satisfies most people's understanding of an ATD is a moot point, but that's what they use.
Hmmm. lets try again...
res ipsa loquitur.
Sacking the crew of this flight doesn't get rid of the issue that permitted the situation to arise in the first place. That problem, like pilot skills and SA were absent from the cockpit on the day (or night). But certainly, sacking the "abberant" crew sure works as spack filler on the side of the space shuttle would.
In my humble opinion.
res ipsa loquitur.
Sacking the crew of this flight doesn't get rid of the issue that permitted the situation to arise in the first place. That problem, like pilot skills and SA were absent from the cockpit on the day (or night). But certainly, sacking the "abberant" crew sure works as spack filler on the side of the space shuttle would.
In my humble opinion.
Seriously? A modern jet airliner is nearly flown into the ground and the discussion centres on FR24? Maybe the Mods should set up a new category of FR24 issues. The Av Herald article quotes from the report stating that the PF achieved an 800fpm rate of climb following the FD's. The airlines have successfully taken away the ability to question the information presented to the pilots and handed the control of the aircraft to the automation. Thats the real concern. It has nothing to do with gender or nationality but everything to do with Flt Ops departments training to a minimum standard.
Join Date: Aug 1998
Location: the ridge where the west commences
Posts: 761
Likes: 0
Received 0 Likes
on
0 Posts
Nothing was lost in translation
The report states that "she followed the flight director command" because she followed the flight director command.
The report states that "she followed the flight director command" because she followed the flight director command.
Join Date: Jun 2007
Location: Hotel time zone
Posts: 168
Likes: 0
Received 0 Likes
on
0 Posts
The trend towards the "cure-all dogmatic fundamentalism" towards company procedures, isn't just to be found at EK; I think most large Western airlines are of the thinking that, provided they can legislate/automate a procedure for every conceivable scenario, then there cannot possibly be an accident, no matter how inexperienced/low paid/basically educated/low aptitude/tired/low stick skills the crews are.
Fact of the matter is, it is ineffective, and can often be counterproductive, where we have overwhelming layer upon layer of procedure, and when the particularly dim witted stumble into conflicting SOP minutiae, rather than acting and applying airmanship, they go into meltdown, and freeze.
Fact of the matter is, it is ineffective, and can often be counterproductive, where we have overwhelming layer upon layer of procedure, and when the particularly dim witted stumble into conflicting SOP minutiae, rather than acting and applying airmanship, they go into meltdown, and freeze.
Originally Posted by Time Traveller
The trend towards the "cure-all dogmatic fundamentalism" towards company procedures, isn't just to be found at EK; I think most large Western airlines are of the thinking that, provided they can legislate/automate a procedure for every conceivable scenario, then there cannot possibly be an accident, no matter how inexperienced/low paid/basically educated/low aptitude/tired/low stick skills the crews are.
Fact of the matter is, it is ineffective, and can often be counterproductive, where we have overwhelming layer upon layer of procedure, and when the particularly dim witted stumble into conflicting SOP minutiae, rather than acting and applying airmanship, they go into meltdown, and freeze.
Fact of the matter is, it is ineffective, and can often be counterproductive, where we have overwhelming layer upon layer of procedure, and when the particularly dim witted stumble into conflicting SOP minutiae, rather than acting and applying airmanship, they go into meltdown, and freeze.
The real problem at the moment as regards airmanship stems form the fact that regulators, operators and training organisations are less interested in improving and restoring airmanship than they are in deciding whether it should be called "airpersonship" or "aviatorship".
To quote my favourite (and least favourite) phrase
"The trouble with making things idiot proof is that it simply encourages the development of better idiots"
To quote my favourite (and least favourite) phrase
"The trouble with making things idiot proof is that it simply encourages the development of better idiots"
Originally Posted by Time Traveller
The trend towards the "cure-all dogmatic fundamentalism" towards company procedures, isn't just to be found at EK; . . .
The first organisation I flew for used what I understood to be aviation grade straps for securing freight. They were pulled tight by hand (on the strap itself, not the handle), then secured by a single over-centre and latch movement of the handle that tightened it a further 2cm or so. This ensured that the strap could not be pulled too tight.
Subsequently I worked for another operator that used standard ratchet straps, that could be tightened as much as you could pull on the handle (with approx 10:1 lever, you can easily put 600-800 pounds, or more, of tension on the strap).
I found that the majority of people seemed to be convinced that the tighter they pulled the strap, the safer they were making it.
It may seem slightly counter-intuitive, but as far as I can see, the safest the system can be is when the strap is just snugly tight.
If the tie-down ring pulls out of the rail at 2000lbs force, and the strap has 10 lbs of tension in it, the ring has 1990 lbs in hand. If the strap has 1900 lbs of tension, the system will fail with another 101 lbs of jolting force.
There is a sweet-spot of maximum strength in the system, and tightening the strap beyond that point actually weakens the system.
The problem is that it is very easy to tighten the strap another click, thinking you are improving things, but no-one wants to take the responsibility of loosening the strap a click, even though it may actually be safer.
In my view, a lot of aspects of aviation safety have passed their maximum strength.
Time Traveller sums it up very nicely above -
I think most large Western airlines are of the thinking that, provided they can legislate/automate a procedure for every conceivable scenario, then there cannot possibly be an accident, no matter how inexperienced/low paid/basically educated/low aptitude/tired/low stick skills the crews are.
Fact of the matter is, it is ineffective, and can often be counterproductive, where we have overwhelming layer upon layer of procedure, and [can end up] stumbl[ing] into conflicting SOP minutiae, rather than acting and applying airmanship
Fact of the matter is, it is ineffective, and can often be counterproductive, where we have overwhelming layer upon layer of procedure, and [can end up] stumbl[ing] into conflicting SOP minutiae, rather than acting and applying airmanship
In my view, there are many areas where we have tightened the “Safety Ratchet-Strap” too tight, and in places need to loosen it a click or two.
Join Date: Dec 2008
Location: uk
Posts: 904
Likes: 0
Received 0 Likes
on
0 Posts
Common sense is not very fashionable in the 21st. century.
Display some and someone will quickly point out the error of thinking like that.
The root cause is fear of legal liability.
IMHO
Display some and someone will quickly point out the error of thinking like that.
The root cause is fear of legal liability.
IMHO
Join Date: Dec 2012
Location: ...
Posts: 695
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by macdo
Common sense is not very fashionable in the 21st. century.
Display some and someone will quickly point out the error of thinking like that.
The root cause is fear of legal liability.
IMHO
Display some and someone will quickly point out the error of thinking like that.
The root cause is fear of legal liability.
IMHO
