vc10man

Enter the wrong Flex Temp.........and near catastrophe

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The Canadian Boeing 737 was taking off from Belfast International Airport when a mistake by cabin crew meant its top speed was not hit - and take-off was prevented.

Failing to fly at the required height the plane smashed into the light, but thanks to a lack of runway obstacles, was able to avoid hitting anything else. 

The incident occurred when a crew member entered the outside temperature as-52C instead of the actual temperature of 16C.

The error on the Flight Management Computer meant the assumed temperate thrust only delivered 60% of the thrust required for take-off, in July last year. 

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7 minutes ago, vc10man said:

a mistake by cabin crew

I don,t think you can blame this one on cabin crew! I think it has more to do with the pilots, don't you think?

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13 minutes ago, nawarren said:

I don,t think you can blame this one on cabin crew! I think it has more to do with the pilots, don't you think?

I am NOT blaming the cabin crew----all I did was copy/paste the news article, which was rather long. I too raised my eyebrows when I saw the 'cabin crew' reference, but a newspaper probably cannot distinguish between flightdeck crew and cabin crew.

So, don't blame the messenger!

 

Edited by vc10man
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Wow, that's some sloppy pre-flight setting up for sure. It's no big deal to get it a few degrees wrong, in fact you pretty much will anyway in most cases when compared to the real actual temperature, but out by 68 degrees is more than a little off the mark!

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The whole article doesn't make sense. Since they actually took off, take off wasn't prevented. And things like the Sunwing accident happen more often than you might think! 

But if nothing happens you usually don't read about it 😉  

Edited by FDEdev
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Ok, I am confused.. is it not the responsibility of the pilots to enter this information inside the FMC?

S.

 

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Probably an easier mistake to make than one might think...

They didn't enter the wrong assumed temperature. They both calculated and entered that correctly.

What they did was enter the cruise OAT instead of the ambient OAT.

This resulted in the FMC thrust calculation being wrong. However, that's pretty hard to trap: everywhere they looked to check the assumed temperature/derate (on the EICAS etc) it would have been correct.

The only way to know something was wrong would have been to know that the calculated N1 was wrong. But that information was not available on their takeoff performance calculation software (and frankly I don't think it is on many) and when you're doing derated/reduced thrust takeoffs day in, day out with all sorts of N1 figures, what chance that you have a good "normal" reference baseline? The runway was relatively long, the airport is near sea level... talking purely from a sim perspective, I'm not sure I would be able to pick up at all if the calculated N1/EPR was off.

Of course, you could ask what sort of system requires manual input of the OAT when most every other type senses that automatically...

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6 minutes ago, FDEdev said:

yes it is.

So why they blame the cabin crew in the article? do they mean the pilots? very badly written.

Regards,
S.

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48 minutes ago, vc10man said:

I am NOT blaming the cabin crew----all I did was copy/paste the news article, which was rather long. I too raised my eyebrows when I saw the 'cabin crew' reference, but a newspaper probably cannot distinguish between flightdeck crew and cabin crew.

So, don't blame the messenger!

 

Rick,

Next time you’re quoting an article, you’d be better served to mention that in the preface and put quotes “” around the part you’ve copied and pasted, otherwise we'll assume what you’ve written are your words, not someone else’s. Might want to post the link to the article you’re quoting as well.

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Sorry, Sean.

Here's the headlines on the article.

"

Packed holiday jet smashed into a runway light in near 'catastrophic' accident in Belfast after crew entered the wrong data into its flight computer

  • Canadian Boeing 737 smashed into runway a light at Belfast International Airport
  • The Corfu bound jet had failed to reach required height after a crew mistake 
  • A further system malfunction prevented an alarm alerting the cabin's crew                     "
  •  

    Under which, this 

 " The Sunwing plane hit a light but did manage to fly to Greece without further incident - had there been any other obstacles in the flight path - there could have been a 'catastrophic' incident a report said 

A further malfunction meant staff were not alerted via an alarm to the mistake during take-off at around 3.45pm. 

The Sunwing Airlines plane destined for Corfu then took off from the airport with 'insufficient power to meet regulated performance requirements' and struck the light.   

An investigation found there were no injuries and no damage to the aircraft which continued its flight to Corfu without incident but the report adds that this was only because of a lack of obstacles in the flight path.

The report states: 'It was only the benign nature of the runway clearway and lack of obstacles in the climb-out path which allowed the aircraft to climb away without further collision after it struck the runway light.

                                                                                                                                                   "

 

 

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44 minutes ago, simbol said:

So why they blame the cabin crew in the article? do they mean the pilots? very badly written.

Regards,
S.

Yes, it is a newspaper that probably as I indicated above, in post#3, lumps Flightdeck Crew and Cabin Crew as one and the same Flight Crew.

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Is there an official report available on this incident available from the AAIB?

Edited by ckyliu

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9 minutes ago, ckyliu said:

Is there an official report available on this incident available from the Irish authorities?

AAIB

 

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Thanks for highlighting my error after I'd edited my post to correct it.... I got in to my head the original post referred to Dublin, hence me thinking it came under the IAA rather than AAIB. I do have reasonable knowledge of the boundaries and major settlements within the United Kingdom and its constituent nations, and those of the Irish Republic, I just made an embarrassing misreading.

Thanks for the link Stephen, better than going off some dubious journalism! Somewhat surprised the crew didn't go for TOGA until after rotation, despite recognising the problem far earlier.

Edited by ckyliu

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If you read the official report, it talks a lot about developing a Take-off Performance Monitoring System and explain why the working groups said it was not possible. Since I am definitely not a science guy and therefore fail to understand that(my bad!), can someone (who read the report) explain why it wasn't possible? You have the data: t/o weight, use-able runway length, qnh, N1 value, etc... Is it difficult to develop a software which will say "Hey with this acceleration rate you wont be able to hit VR (or V2) by the time you reach the end of runway, once the take off roll starts?

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From the report: " The aircraft’s FMC did not have the capability to alert the flight crew to the fact that they had entered the incorrect OAT into the FMC, although this capability existed in a later FMC software standard available at the time."

So the solution to this problem looks pretty simple from where I sit...update the FMC software!

 

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Forgive me for my potential lack of understanding, but it looks like the pilots failed in at least two important points, inputting the wrong temp in the fmc and not monitoring their N1 gauge during the take off roll. Stating that it only gave them 60% of the require takeoff power is quite a big discrepancy to not notice at some level, regardless of whether they did the calculations or not. Sure a 5-10% off is understandable but 40%, especially for pilots who have many hours in that flight deck?

Edited by Kevin_28
was going to delete, but someone already posted a response, so might as well keep it.

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10 minutes ago, Kevin_28 said:

Forgive me for my potential lack of understanding, but it looks like the pilots failed in at least two important points, inputting the wrong temp in the fmc and not monitoring their N1 gauge during the take off roll. Stating that it only gave them 60% of the require takeoff power is quite a big discrepancy to not notice at some level, regardless of whether they did the calculations or not. Sure a 5-10% off is understandable but 40%, especially for pilots who have many hours in that flight deck?

The actual N1 was about 81% -- a little low but perhaps not entirely unreasonably so (and only about 10% N1 less than the actual required setting of about 90% N1).

The "60%" figure AFAIK is based on an estimation of the actual thrust output (i.e. in lbf) (which is obviously non-linear with N1). 

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1 hour ago, w6kd said:

So the solution to this problem looks pretty simple from where I sit...update the FMC software!

 

That's what they did in the end 🙂
 

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