While I am not very confident we will see a 777 profile added to TOPCAT, I am sure not after long the 777 is released some genius will release an excel spreadsheet similar to what we have now for the NGX which will incorporate take-off performance and landing calculations.

 

Until then, all I can suggest you do is source a FPPM from somewhere on the internet and learn how to read the take-off performance charts/tables.. It really is just a simple matter of going down and across charts and finding your figures... That's how we used to do it before we had AAM's (Airport Analysis Manuals) and now OPT/LPC computer laptops :good:

 

....or you could just guess a de-rate figure and risk ending up in the localiser

 

....or firewall it down the runway :Party:

[pedant mode on]McDonnell Douglas also used FLEX as the reduced thrust via assumed temperature reference[/pedant mode off]

 

Sorry Kyle, couldn't help it

 

 

Sent from my iPhone using Tapatalk

 

It's true though.

Very interesting discussion going on here, but I can't help but nitpick about the EK tailstrike incident. It did not occur in Sydney as has been stated but in Melbourne. Close to 400nm southwest.

 

If it did occur in Sydney they would be risking going off into Botany Bay. 

There's no issue with safety at all when if comes to using FLEX temp/ATM, in fact, using TOGA increases the risk of FOD ingestion as well as compressor stalls at low speed. 

 

Just because two pilots entered the wrong number in once, doesn't mean that you should automatically just forget that system and always go for max thrust, it just doesn't make sense.

 

An analogy to show just what a silly idea that is would be to take the case where pilots calculated the wrong fuel for the flight, and had to divert early because of it. To avoid this situation happening again, the solution is not to always fill the tanks to the brim and then know that you've certainly got enough fuel, but to make sure you double and cross check the figures before you even leave the crew room.

 

Less than 1% of all flights will use TOGA. Given that there are 90,000 commercial flights a day in the world, that means that every day 89,100 flights use Flex thrust without incident. That means that in the 4 and a bit years since that incident, over 140,778,000 flights have safely used FLEX/ATM thrust takeoffs without issue. Sounds pretty safe to me.

 

Regards,

Ró.

 

 

it just doesn't make sense

 

and you fly Airbus! hahaha  :lol:

 

Kidding man.  Good post.  Makes sense.  

There's no issue with safety at all when if comes to using FLEX temp/ATM, in fact, using TOGA increases the risk of FOD ingestion as well as compressor stalls at low speed.

 

Just because two pilots entered the wrong number in once, doesn't mean that you should automatically just forget that system and always go for max thrust, it just doesn't make sense.

 

An analogy to show just what a silly idea that is would be to take the case where pilots calculated the wrong fuel for the flight, and had to divert early because of it. To avoid this situation happening again, the solution is not to always fill the tanks to the brim and then know that you've certainly got enough fuel, but to make sure you double and cross check the figures before you even leave the crew room.

 

Less than 1% of all flights will use TOGA. Given that there are 90,000 commercial flights a day in the world, that means that every day 89,100 flights use Flex thrust without incident. That means that in the 4 and a bit years since that incident, over 140,778,000 flights have safely used FLEX/ATM thrust takeoffs without issue. Sounds pretty safe to me.

 

Regards,

Ró.

Thanks for putting this FLEX/ATM issue to bed Rónán it makes sense.

 

 

Sent from my iPhone using Tapatalk

Less than 1% of all flights will use TOGA. Given that there are 90,000 commercial flights a day in the world, that means that every day 89,100 flights use Flex thrust without incident. That means that in the 4 and a bit years since that incident, over 140,778,000 flights have safely used FLEX/ATM thrust takeoffs without issue. Sounds pretty safe to me.

 

Good point.

 

Best regards,

Robin.

Hi All,

 

As well as saving money from less wear on the engines, derates also put less stress on the engines in a critical phase of flight, i.e. takeoff. This helps prevent engine failures etc. on takeoff. It's a win win for the airlines and they will always try and derate whenever they can.

 

Derate has another advantage to busy crews, in that things will happen slower than at max thrust, they will be less likely to bust an altitude limit, or overspeed the flaps. To blame derates for the cause of this crash is missing the point entirely.

 

The simple fact is the crews made a basic error that could have had far harsher consequences. I do not judge them for it, as it's easy sitting on a sofa with 20 20 hindsight to be an expert. I'm afraid there will always be such accidents with humans in the loop.

 

Cheers

 

Neil

 

Cheers

 

Neil

The argument against FLEX seems to come from an assumption that safety is being traded for reduced cost, which sounds evil on the face of it.

 

But my reading of reducing engine wear is that in fact that means a substantially greater increase in safety, due to reduction of risks associated with maintenance, or the outright risk of engine failure due to wear, so that the overall safety margin is thereby _improved_ as a result of FLEX.

 

Which is not evil.

 

There's no issue with safety at all when if comes to using FLEX temp/ATM, in fact, using TOGA increases the risk of FOD ingestion as well as compressor stalls at low speed.

 

Just because two pilots entered the wrong number in once, doesn't mean that you should automatically just forget that system and always go for max thrust, it just doesn't make sense.

 

An analogy to show just what a silly idea that is would be to take the case where pilots calculated the wrong fuel for the flight, and had to divert early because of it. To avoid this situation happening again, the solution is not to always fill the tanks to the brim and then know that you've certainly got enough fuel, but to make sure you double and cross check the figures before you even leave the crew room.

 

Less than 1% of all flights will use TOGA. Given that there are 90,000 commercial flights a day in the world, that means that every day 89,100 flights use Flex thrust without incident. That means that in the 4 and a bit years since that incident, over 140,778,000 flights have safely used FLEX/ATM thrust takeoffs without issue. Sounds pretty safe to me.

 

Regards,

Ró.

It's also, always, a balancing act; for every system designed to cross-check and guarantee proper programming for conditions, there will always be an edge case that isn't accounted for. This is a fact of programming, no matter how complicated or simple (also true for project management, which done at scale is a form of team- and work-programming, seen clearly, and is why things take longer and cost more to do than any system no matter how expert can predict; cf. current US F-35 development program......).

 

Creating safeties is always a fuzzy process; it's amazing that things work as well and as often as they do.

 

That incident had nothing to do with de-rating being dangerous and everything to do with the fact they punched in the wrong weights on the computer and it wasn't double checked. It should be common sense to pilots on an aircraft they've flown for years that if you're taking off anywhere near the MTOW and the computer is giving you a high FLEX temp (and low vspeeds/small difference between V1/VR) - something has probably gone wrong, especially given that the runways at YSSY are not unusually long (longest is 4000m), so pretty standard for the major international airports.

 

I think it's a bit silly to recommend people "don't use it" just because an incident exists where pilots didn't have the common sense to realise something was up, or the common decency to make sure they don't punch in a TOW that is 100 tonnes less than their actual weight. 

 

Of course, they even managed to input a weight that was considerably less than the empty weight plus the fuel they were carrying, alarm bells should've instantly been going off in their heads. Although the aspect of it that really confuses me is how on earth they were willing to accept the, what must've been, unusually low v-speeds. Given that they were Emirates pilots, and their A345s are, as far as I know, entirely used for long-haul routes the v-speeds given by the EFB would have been 30 knots less than the usual v-speeds for an A345 Emirates flight - yet this didn't seem to perplex them? 

 

 

This incident occurred at Melbourne, not Sydney. It was an error in the performance calculations. Although the crew did punch in the incorrect weight data, the fact is the PF was alternating between operating the 330 and 340; this was identified in the ATSB report and played a major factor as to why a 100 ton discrepancy wasn't picked up.  The Capt was the only pilot on the flight deck who had not operated on both the A330 and A340 in the preceding 90 days.  Fatigue played a role also, the Capt of EK407 had flown 99 hours of the 100 per month allowed by Emirates.

I'm sure Boeing,Airbus GE,PW, and RR as well as every other aircraft manufacturer does extensive testing prior to find what the end result is on wear or pushing limits on engines have. There is a reason they come up with all that data for assumed temp/flex.

 

Its also part of every companies SOP I believe of when and how it should be used. Taking a temp or create that leaves 3000 ft of runway or if less than 2000 must be TOGA. Etc etc.

 

It works great on the md11, providing you crunch the numbers correctly. This also means you put in the right runway and it has the correct length. I know from experience in putting in 2L from 2R makes a big difference sometimes. -_-

I think it's Assumed TeMperature, to differentiate it and AT for Auto-Throttle. I didn't run off into the manuals to figure out what it means precisely, however.

 

...but yes, you'll be saving money on engine costs, though not fuel.

I thought it was Assumed Temperature Method, but I could be wrong. Fokker also used Flex, fairly sure Embraer do too. So pretty much everybody uses Flex except Boeing.

 

Strictly speaking, Flex is the name of the thrust mode, not the assumed temperature.

 

 

I thought it was Assumed Temperature Method, but I could be wrong.

 

Nope!  That's it!  I went back through the FCTM after posting that to check and then forgot to come back and correct it.

 

 

 

Fokker also used Flex, fairly sure Embraer do too. So pretty much everybody uses Flex except Boeing.

 

haha - good to know.