Quoting md80fanatic (Reply 194):

Thanks for your comments . I used the term human error instead of pilot error to highlight the fact that weather has not caused a crash in a while.

The Cargo 747 - was human error if cargo not properly secured, and mechanical error if the straps and chains failed.

Sully -- I stand corrected - avian error !

ET - pilot error
Perpignan - pilot error
BA777 - agree
Afriqiyah - pilot error
SSJ - pilot error
AF447 - pilot error
Continental Buffalo - pilot error
Pulkova - pilot error.

The only wx related incident was the Air Algerie take off into a CB in Mali But was it a preventable accident? In modern aviation, is flying into dangerous weather a weather-related problem or a pilotage issue?

Quoting RickNRoll (Reply 193):

Thanks. My question now is if CB enroute that day was considered a risk to the flight. When you dispatch a flight in the ITCZ , is it considered riskier than a flight on a calm sunny day in the US? If so, should pax and crew be advised of this increased risk?

"Pilot error" makes it sound as it was a walk in a park and they blew it…

Isn't Tony Fernandes making a generalized statement regarding en-route wx, rather than a specific claim regarding 8501 on morning of Dec. 28? It's like saying a fatal auto accident at 3am early Saturday morning was likely alcohol related because statistics demonstrate that, during that time slot alcohol related traffic deaths are the highest percentage-wise.

The weather that morning was standard issue ITCZ and nothing really noteworthy for that time of the year in that part of the world, and as we know 5 other flights within minutes of each other made their destination safely without reportable incident. In that regard, IMHO, Mr. Fernandes is deflecting a bit, probably in an effort to console until such a time that the real answer becomes known. I would also expect Airbus to follow suit since their baby was just launched/delivered featuring the same flight control system, still under some scutiny in other recent events.

I feel there are two most likely scenarios with 8501.

1) High altitude upset leaving structure compromised and ultimately unrecoverable. Hand-flight at cruise level is a very touchy thing most modern pilots are only obliquelly familiar with. It is a regime where a heavy hand can get you into trouble, fast. I've heard that controls can feel "mushy" or like a "bungy cord" (as described yesterday on pprune). We don't know yet what mode the plane was in when it departed controlled flight and the FDR will tell us soon enough.

2) Terrorism. Indonesia is a majority Muslim country, and the Sunday following Christmas is trditionally a high load travel day for Christians going home from their holiday celebrations. As would be expected the majority of this flight were Indonesians, and the majority of those were Christians. You do the math. There in much to lose for the industry if people become scared to fly.

[Edited 2015-01-15 04:52:34]

While is too early to know if the aircraft was intact at 0 feet or not the autopsy of those who perished will shed light if they were indeed seated and falling down flat in a stall.

I really hope the blackboxes will clear the events of that tragedy since some facts are confusing, because other flights were on the vicinity ...

TRB

Quoting md80fanatic (Reply 202): I feel there are two most likely scenarios with 8501. 1) High altitude upset leaving structure compromised and ultimately unrecoverable. Hand-flight at cruise level is a very touchy thing most modern pilots are only obliquelly familiar with. It is a regime where a heavy hand can get you into trouble, fast.

Why do you think they would be hand flying at cruise altitude? That's highly unlikely as a cause for this accident.

Quoting flyingturtle (Reply 203):

I have the highest respect for pilots and surgeons since I trust them with my lives. More so pilots, as they are exposed to the same risks I am.

All humans are prone to error, especially when operating highly automated equipment. My feeling is that accidents are aggravated by the interaction between man and machine, so to just blame the pilot misses the point in a chain reaction of events.

Let's wait and see what the DFDR tells us - how does a modern airliner, on a morning flight over familiar ground, get into this kind of trouble?

Quoting md80fanatic (Reply 202): Hand-flight at cruise level is a very touchy thing most modern pilots are only obliquelly familiar with. It is a regime where a heavy hand can get you into trouble, fast. I've heard that controls can feel "mushy" or like a "bungy cord" (as described yesterday on pprune).

Unless the airplane is flying at an altitude way above the altitude for its given weight that comment is total b******t, especially in a FBW airplane. If you're at an altitude where the maximum/minimum maneuver speed amber bars overlap then things are a bit dicey but that's not where the airplane is flown.

This may help some of the sensationalists still theorising about inflight breakups get their head around why some of the debris is so spread out. Very strong currents indeed.

http://www.businessinsider.com/afp-d...-in-hunt-for-airasia-debris-2015-1

Quoting 675kts (Reply 208): This may help some of the sensationalists still theorising about inflight breakups get their head around why some of the debris is so spread out. Very strong currents indeed.

Of course there were strong currents. As I mentioned a day ago, the tail would willingly break off during impact with the ocean - from where, due to the nature of the sea-level weather at the time - it would be COMPLETELY possible for it to drive a kilometer or two. This plane hit the water intact.

Report indicating that voice cockpit recorder heard a voice saying "Allah Akbar".

http://downtrend.com/robertgehl/brea...doomed-airasia-flight-allah-akbar/

Quoting heyjoojoo (Reply 210): Report indicating that voice cockpit recorder heard a voice saying "Allah Akbar". http://downtrend.com/robertgehl/brea...doomed-airasia-flight-allah-akbar/

Sorry that source is not credible at all.

Quoting heyjoojoo (Reply 210): Report indicating that voice cockpit recorder heard a voice saying "Allah Akbar".

This was posted on Yahoo! News and they appropriately missed the following sentence at the end!

“It is as if we can feel them… Allahuakhbar, Allahuakhbar were the last words said before they died,” he said referring to his experience analysing black boxes from past crashes.


Jimbo

PLEASE tell me they heard it wrong! We don't need another EgyptAir 990!

Quoting 32andBelow (Reply 211):

Apart from not being credible, that phrase doesn't necessarily mean terrorism...

I'm not Muslim, but isn't that phrase also used in praying?

Which, you might do in perilous situations.

Even if they did say it (which there is no proof they did), it does not mean that they were terrorists. They could have just been religious and knew what was happening.

Quoting rj777 (Reply 213): PLEASE tell me they heard it wrong! We don't need another EgyptAir 990!

Are you serious??

Generally people tend to get quite religious the moment before they know they are going to die.

With reference to the official BEA Simulation regarding the Air France 447 Crash (and regarding any relevance to Air Asia 8501):
https://www.youtube.com/watch?v=n-hbWO0gL6g

Around 02:10:47Z the Flight Director Bars on AF 447 noted on the Left PFD started coming back intermittently (previous to this time and starting around 02:10:08Z they were not displayed as a result of the pitot tube icing condition). The pilot in the R seat (flying) seems to be following the Flight Director bars as they appear/reappear intermittently (as noted on the R side stick inputs). This results in the stall alarm around 02:10:52Z, with the L PFD showing around a 10 Deg. Pitch Up at that time.

Around 02:10:57Z the Flight Director Bars as noted on the Left PFD come back and stay on continuously (and the stall alarm initiated at 02:10:52Z continues). The right seat pilot (flying), even though in a (worsening) stall (and the stall alarm blaring) continues to follow the Flight Director bars (pitch and roll) as noted on the L PFD and the right side sidestick inputs. With the stall worsening and the AOA increasing the right seat pilot (flying) continues to follow the Flight Director bars, even with a F/D commanded/displayed 20 deg. pitch up, and (negative) vertical speed increasing and altitude decreasing rapidly. Around 02:11:40 the F/D bars again disappear, but at that point the aircraft is in a very deep stall, V/S around -8500 fpm, pitch still around 10 deg. up, right seat sidestick (pilot flying) with a nearly (IMO) unbelievable 80% nose up (and holding) and 100% L roll input and stall warning still blaring. The stall progresses until impact with the Ocean.

My question is this, and may have been answered previously, why when already in a stall did the AF 447 Airbus Flight Director bars continue to command a nose up pitch on the PFD, and which via the AF 447 simulation it certainly appears the right seat pilot (flying) was following via right side sidestick inputs to meet the F/D commanded pitch and roll despite the worsening stall? And by the time the Captain returned and eventually sorted out/figured out what was going on, and to command nose down pitch to break the stall it was too late?

Could there be similarities in the evolution of these two events, i.e. AF447 and Air Asia 8501 (the final DFDR and CVR data will of course objectively disclose), as from the recovered aircraft debris pictures, etc. IMO it appears that a stall may have been present with the aircraft likely impacting the water at a somewhat nose up attitude and likely at very high neg. vertical speed and low forward speed.

Quoting cat3appr50 (Reply 217): why when already in a stall did the AF 447 Airbus Flight Director bars continue to command a nose up pitch on the PFD, and which via the AF 447 simulation it certainly appears the right seat pilot (flying) was following via right side sidestick inputs to meet the F/D commanded pitch and roll despite the worsening stall?

I am certainly no expert but my understanding is that if the crew had followed the unreliable airspeed procedure this issue would not have arisen.

Quoting cat3appr50 (Reply 217): And by the time the Captain returned and eventually sorted out/figured out what was going on, and to command nose down pitch to break the stall it was too late?

There's no evidence the captain ever knew precisely what was going on. See reply 158 above

Quoting kaneporta1 (Reply 183): Quoting Kaiarahi (Reply 176): Do you understand what a "deep stall" is? Hint - the TU154 is a t-tail, the A320 not so much. Sigh. Where I come from there is a saying "You see the tree but you miss the forest". Did you even read anything before and after the phrase "deep stall"?

Re-read what you posted on Pulkovo612. "Deep stall" on a t-tail such as the TU154 refers to a situation where the horizontal stabilizer (tailplane) is stalled because the airflow is blanked by the wings, resulting in no pitch authority. It is exceedingly difficult to recover from, and usually results in the plane continuing to pitch up to AOAs such as that experienced by Pulkovo612.

Quoting heyjoojoo (Reply 210): http://downtrend.com/robertgehl/brea...doomed-airasia-flight-allah-akbar/

That "report" has since been removed, as has the "report" on Yahoo.

Quoting Kaiarahi (Reply 219): That "report" has since been removed, as has the "report" on Yahoo

And now its popped up on the oh-so-down-to-earth daily mail.

http://www.dailymail.co.uk/news/arti...iends-pilot-examine-black-box.html

Quoting cat3appr50 (Reply 217): And by the time the Captain returned . . .

By the time the Captain returned the plane was already doomed.

Quoting liquidair (Reply 220): Quoting Kaiarahi (Reply 219): That "report" has since been removed, as has the "report" on Yahoo And now its popped up on the oh-so-down-to-earth daily mail. http://www.dailymail.co.uk/news/arti...iends-pilot-examine-black-box.html

I don't see anything in that article to suggest that the investigators believe it was pilot suicide. My understanding of Islam is that Allah akbar is a brief prayer, often said by observants who believe they are about to be injured or die. Like, "Oh God" or "God help me" in English.

Weren't those the last words found on the CVRs in other crashes in the Muslim world? I seem to recall the Garuda plane that CFIT'ed finding that too, as they suddenly realized they were on a collision course.

Quoting 675kts (Reply 208): This may help some of the sensationalists still theorising about inflight breakups

mandala is not a sensationalist of any sort.

There's always the chance that it could be a "prayer". But then again we've seen instances of suicide attacks and other forms of terrorism usually being preceded with chants and exhortations of the same words.

Quoting heyjoojoo (Reply 224): There's always the chance that it could be a "prayer". But then again we've seen instances of suicide attacks and other forms of terrorism usually being preceded with chants and exhortations of the same words.

It has nothing to do with PK-AXC. The person was talking about what you tend to hear on CVRs in general. He was not talking about the crash of PK-AXC.

The media simply added that spin and ran with it.

Quoting heyjoojoo (Reply 224):

In all decency and respect for the deceased, can't you at least wait until this gutter press "rumour" is confirmed or not before speculating about terrorist pilots.

http://www.straitstimes.com/sites/st.../20150115/underswterairsi1501e.jpg

I have not seen this pic before.

Is it where the tail broke off of the fuselage?

[Edited 2015-01-15 12:31:03]

[Edited 2015-01-15 12:34:59]

Quoting heyjoojoo (Reply 224): There's always the chance that it could be a "prayer". But then again we've seen instances of suicide attacks and other forms of terrorism usually being preceded with chants and exhortations of the same words.

I would bet 99.999999% of the time that phrase is uttered, it has nothing to do with terrorism. It's part of the call to worship, for instance.

When you hear hooves, think horses before you think zebras. Or unicorns, for that matter.

http://www.straitstimes.com/sites/st.../20150115/underswterairsi1501e.jpg

http://localtvwiti.files.wordpress.com/2015/01/s041959482.jpg

I believe that is the same area, just a little closer look.

Is that the left H-stab?

[Edited 2015-01-15 12:44:46]

[Edited 2015-01-15 12:45:46]

Quoting LTC8K6 (Reply 225): It has nothing to do with PK-AXC. The person was talking about what you tend to hear on CVRs in general. He was not talking about the crash of PK-AXC.

That's how I read it. He was talking about CVR transcripts from previous accidents... with no mention of suicide or terrorism

Quoting heyjoojoo (Reply 224): There's always the chance that it could be a "prayer". But then again we've seen instances of suicide attacks and other forms of terrorism usually being preceded with chants and exhortations of the same words.

We went through all this in the MS990 discussions. The evidence that it was a deliberate act lay elsewhere, e.g. the "discussion" between the Captain and the FO, the opposing forces on the yokes, the fuel levers being moved to Cut-off, etc.

Quoting D L X (Reply 228): I would bet 99.999999% of the time that phrase is uttered, it has nothing to do with terrorism. It's part of the call to worship, for instance.

That's what I understand. The phrase is often uttered in anticipation of, or reaction to, challenging or unpleasant circumstances.

Throughout the ten forum parts on this topic, few posters have mentioned any possibility of a suicide crash, or what about a fight or struggle on the flight deck? Perhaps the cause of this crash is not weather related at all.

Quoting awthompson (Reply 231):

we had no reason to, and we don't now.

Quoting awthompson (Reply 231):

We are only allowed to jump to conclusions we have done so far like weather-related thus far but not jump to conclusions of other possibilities. Lol.

Quoting David L (Reply 230): That's what I understand. The phrase is often uttered in anticipation of, or reaction to, challenging or unpleasant circumstances.

Yeah, if one listens for example Adam Air 574 CVR pilots can be heard shouting this prayer while their aircraft was diving out of control. I think it wouldn't be abnormal or unexpected at all if it was found from the CVR of Air Asia crash also. I'm sure many CVR's of western aircraft that crashed have "Oh my god" and similar sentences in them.

[Edited 2015-01-15 13:45:42]

Quoting hivue (Reply 205): Why do you think they would be hand flying at cruise altitude?

Only because it is one way that a perfectly serviceable airliner could end up in the ocean 7 miles below. Why they would be doing so I do not know. They -should- be doing so, often, in case they ever need to ... so when the AP throws it into their hands by surprise one dark night they don't have to go into it cold turkey. I don't care about pax comfort, or fuel burn ... I don't want my pilot's first real experience in very thin air to be when pax are aboard.

Quoting 7BOEING7 (Reply 207): Unless the airplane is flying at an altitude way above the altitude for its given weight that comment is total b******t

Ceiling is around 39000 ft (minimum weight - empty) and plane was 90% full, so perhaps 37500 to 38000 ft. Wasn't that the altitude the PF requested? "Way above"? Are you saying unless the plane is "way above" that altitude then the experience of hand flying at 36000 ft is the same as it is at say ... 500 ft? It doesn't take a pilot to know that's ********. Physics is physics whether you fly the heavy iron or swing a 7-iron.

Quoting 675kts (Reply 208): This may help some of the sensationalists still theorising about inflight breakups get their head around why some of the debris is so spread out. Very strong currents indeed.

None of the recovered wreckage could float for even 3 minutes, much less 1 hour. Might as well get on board with the "sensationalists" because dreaming of sheet aluminum and bundles of wires and hoses floating at all is fantasyland.

Quoting Trin (Reply 209): This plane hit the water intact.

Then it had to hit with near zero forward velocity ... because parts of the wing that would easily shear away (like flaps and slats) are lying right below the wrecked wing on the sea floor (despite currents that everyone seems to be convinced could drag this wreckage across the sea floor for miles and miles).

If it hit intact then there would be two wings and two engines within visual range of the fuselage.

Quoting md80fanatic (Reply 194): That's pretty broad, don't you think? UPS 747, Lithium battery overrun in the hold - fire Cargo 747, cargo shift on takeoff - CoG BA 777, adulterated fuel - dual flameout Sully's A320, birdstrike - dual flameout to name just four. I suppose you could call two of these human error, such as choosing to fly proven dangerous batteries, or improperly securing armored vehicles ... but none were the faults of the flight crew.

I understand here you were only providing a quick list to make a point, but please do some research regarding the BA777 incident at London Heathrow. You will find it very interesting.
For the record and to ensure that readers here don't go off thinking adulterated fuel was the cause, this was not a factor.
The fuel which was taken on at PEK was tested and was within all normal parameters.
After a lengthy investigation which included a painstaking lab re-run of the complete fuel system from the written off G-YMMM in similar temperatures to the actual BA38 flight, it was finally concluded that cold soak of fuel in extremely low temperatures while aircraft cruised for many hours at FL400 over Siberia, caused minute ice crystals to form in the fuel (not that unusual) but then accumulate on the faces of the fuel/oil heat exchangers (FOHE) on a power increase to maintain glide slope, temporarily restricting fuel flow resulting in simultaneous loss of power to both engines on final approach. The FOHEs for that type of engine were re-designed and also procedures governing long cruises in particularly low temperatures were revised to include a power setting cycle every so often to agitate the fuel and so reduce likelihood of a similar situation recurring.

Quoting hivue (Reply 205): Why do you think they would be hand flying at cruise altitude? That's highly unlikely as a cause for this accident.

By definition, *everything* is highly unlikely as a cause of this accident. If something's not impossible - and some things definitely are, whether generally or based on the known facts of a particular case - then it's fodder for discussion.

The resident pilots here can definitely override anything I'm about to say, but my understanding is that pilots do occasionally hand-fly at altitude for various reasons, including (especially?) in turbulence. There could also have been a problem with the auto-pilot or some other system, either pre-existing but not MEL'd or something that developed en route. There's no public indication yet that that was the case here, but it's no less possible than many other things we've talked about.

Quoting D L X (Reply 228): When you hear hooves, think horses before you think zebras. Or unicorns, for that matter.

That's a great quote, I'm going to steal it! "Allahu Akbar" has got to be one of the most misunderstood religious sayings in the western world. A lot of westerners say things like "My God!" when they're startled and don't think anything of it - and many of those people aren't even religious.

Quoting awthompson (Reply 231): few posters have mentioned any possibility of a suicide crash, or what about a fight or struggle on the flight deck?

It doesn't fit the facts we already know, including the photos. A suicidal pilot isn't going to bellyflop his plane into the water, which is what the damage seems to suggest in this case. All of the other pilot suicides we've seen have been straight, almost perpendicular high-speed dives into the water that completely shattered the plane. If someone's committing suicide by plane, they want it to be quick and painless. They don't want to take the chance of either themselves or anyone else surviving - so an intentional crash like this wouldn't make sense.

Quoting Kaiarahi (Reply 226): In all decency and respect for the deceased, can't you at least wait until this gutter press "rumour" is confirmed or not before speculating about terrorist pilots.

   Well said. What harmful nonsense.

Riv'

Quoting awthompson (Reply 236): I understand here you were only providing a quick list to make a point, but please do some research regarding the BA777 incident at London Heathrow. You will find it very interesting.

I know what the "official" cause was said to be .. I just don't fully believe it. Had just one engine experienced the problem during final that would be another story, but two ... simultaneously, with independent tanks and FOHEs? Anyway ... I understand your point, and I really should have left my opinion out of it and stated the "official" spiel. It was late and I was already in my jammies and ready to retire. My apologies.

Quoting heyjoojoo (Reply 233): We are only allowed to jump to conclusions we have done so far like weather-related thus far but not jump to conclusions of other possibilities. Lol.

We can all do this. I think it got hit by a meteor.

It's another possibility with as much evidence as terrorism!

Quoting md80fanatic (Reply 235): None of the recovered wreckage could float for even 3 minutes, much less 1 hour.

Absolutely untrue. The tail can absolutely float, and for extended periods of time.

Witness AF447's tail. Days later, not only was it still floating, but it still had enough positive buoyancy for several very burly salvage divers to stand on top of it while rigging straps to lift it onto their ship.

What was attached to QZ8501's tail was mostly shell; and mostly from the upper fuselage. Very thin aluminum skin, with some associated structural components.

While we can't tell for sure (since we don't have the actual wreckage in hand), and we'll have to wait for the final report to find out ...

It's quite reasonable to conceive of a scenario where the tail ruptures on impact, and the tail (with attached wreckage) floats for quite a bit before finally succumbing and sinking.

Quoting coolian2 (Reply 240): We can all do this. I think it got hit by a meteor. It's another possibility with as much evidence as terrorism!

Welllll, I don't see the FAA erecting a giant infrastructure to monitor incoming meteors that may endanger civil aeronautics. They do seem to be quite overly-concerned about terrorism though, along with the Thousands Standing Around agency. Just sayin'

Quoting md80fanatic (Reply 242): Welllll, I don't see the FAA erecting a giant infrastructure to monitor incoming meteors that may endanger civil aeronautics. They do seem to be quite overly-concerned about terrorism though, along with the Thousands Standing Around agency. Just sayin'

I think he's saying (and i agree) that jumping to the conclusion of terrorism based upon some common words in the CVR is improper. Not that we need to go out and monitor meteors. Look at the posts he's responding to.

Quoting md80fanatic (Reply 235): Ceiling is around 39000 ft (minimum weight - empty) and plane was 90% full, so perhaps 37500 to 38000 ft. Wasn't that the altitude the PF requested? "Way above"? Are you saying unless the plane is "way above" that altitude then the experience of hand flying at 36000 ft is the same as it is at say ... 500 ft? It doesn't take a pilot to know that's ********. Physics is physics whether you fly the heavy iron or swing a 7-iron.

First the ceiling of 39,000 ft is not based on "minimum weight-empty" and although it was 90% full of passengers it was probably less than 50% full of fuel. FL380 was most likely well within the capability of the airplane. Second, for a trained pilot hand flying a modern airliner at altitude is not difficult and even easier on a FBW airplane -- anybody that tells you differently is either not a pilot or doesn't belong in the cockpit. I've flown with hundreds of airline pilots from all over the world in everything from a 737 to a 777 and none of them had any problem manually flying the airplane at altitude. You make it sound like it's a scary proposition.

Quoting litz (Reply 241): Absolutely untrue. The tail can absolutely float, and for extended periods of time. Witness AF447's tail. Days later, not only was it still floating, but it still had enough positive buoyancy for several very burly salvage divers to stand on top of it while rigging straps to lift it onto their ship.

You are talking about an intact VS (AF447), versus a broken VS (8501) that is almost 1/3 of the surface area ... holding a hulk of broken fuselage that took 3 rather large balloons to lift off the sea floor. AF447's VS was intact and if not found could have washed up on a beach one day.

8501's able to support such weight, while broken, absolutely not. I'm sorry.

Quoting D L X (Reply 243): Look at the posts he's responding to.

I just did, and I agree fully.

Quoting 7BOEING7 (Reply 244): I've flown with hundreds of airline pilots from all over the world in everything from a 737 to a 777 and none of them had any problem manually flying the airplane at altitude. You make it sound like it's a scary proposition.

Very well ... just wondering why many old-timers at pprune seem to differ, and often. Perhaps they mean in adverse conditions, not nice smooth air? Either way, I think both of you agree that it is indeed more of a challenge and there is much less room for error, up there.  

BTW, how does your FBW do (Airbus) hand flying at cruise in Direct Law? I would imagine it would be quite a bit more challenging than Normal or Alternate.

Quoting 7BOEING7 (Reply 244): FL380 was most likely well within the capability of the airplane.

I should hope so, since that was what they were filed for.

Quoting Kaiarahi (Reply 219): Re-read what you posted on Pulkovo612. "Deep stall" on a t-tail such as the TU154 refers to a situation where the horizontal stabilizer (tailplane) is stalled because the airflow is blanked by the wings, resulting in no pitch authority. It is exceedingly difficult to recover from, and usually results in the plane continuing to pitch up to AOAs such as that experienced by Pulkovo612.

Here's what I posted:

Quoting kaneporta1 (Reply 167): However from what I understand to be accurate information: There was bad weather and the aircraft was trying to deviate around it. There was a rapid climb. Followed by a rapid descend. ...All the above is eerily similar to Pulkovo flight 612:

The rest was from the report as found on the aviation safety database. At no point I mentioned that QZ8501 was an exact replica of what happened to the TU-154. The report also mentioned that the TU-154 pilots were on manual control. I'm surprised you didn't pick on that and then make a fuss about how Airbus pilots wouldn't do that...

And yes, I know very well what a deep stall is. Do you know how to distinguish between the main point of a subject and the not necessarily relevant details?