Posts by user "Bap7788" [Posts: 5 Total up-votes: 0 Pages: 1]

Bap7788
2025-06-18T11:50:00
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Post: 11905173
Hi all,

Disclaimer: I read this thread from hour 1, still scratching my head regarding perf though.

I know sound analysis points to higher odds being a dual engine failure with RAT deployed, however I still have some questions if anyone is available to enlighten.

So, my questions is related to T/O performance.

Is it possible on the 787 to calculate perf in the OPT for F15/20 T/O, and to enter F5 T/O speed on the FMC ?

By that I mean do normal procedure, but at the point where you are suppose to enter flaps, CG speed ect…. You, out of habit (if F5 is indeed a habit on the 787) enter F5, but F15/20 speeds ? Or would there be a warning that you have manually inputed speeds that are not correct for the selected flaps and conditions inputed in the FMC ?

Thanks for the help !

Subjects: Dual Engine Failure  Engine Failure (All)  RAT (All)  RAT (Deployment)

Bap7788
2025-06-18T12:26:00
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Post: 11905199
Originally Posted by mechpowi
An FCOM available in the net says that the FMC doesn\x92t accept Vr entry lower than Vr min or V1 min.
amazing thanks for the help !

I think this has been answered for 76 and 77 on the first thread but I can\x92t recall an answer for 78.
Can anyone confirm if you have inputed F15 in the FMC but selected F5 you would have some sort of FMC message displayed ?

Subjects: FCOM  V1

Bap7788
2025-06-18T18:57:00
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Post: 11905470
Originally Posted by Magplug
Capn Bloggs We shall see!

A mate tried gear/flap scenario in the sim earlier. Selecting flaps up (all the way) instead of the gear did not predjudice the flight path at all. They selected flaps up at normal gear retraction height and punched the AP in. The Slats remained out until 225kts (as per my post about 50 pages ago) and the aircraft climbed happily away clearing all obstacle by a good margin.
can you ask him by any chance what the outcome would be with f15 or 20 speeds, but in a F5 config and a rotation at VrF15 ?
and retract the flaps to 1 instead of gear ?
sorry I don\x92t know if that has been tested already.

Subjects: Flaps (All)  Flaps vs Gear  Gear Retraction

Bap7788
2025-06-19T18:02:00
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Post: 11906235
Originally Posted by Magplug
Had a play with this scenario in the sim today and learnt a few things:
1) Incorrect performance data... It has to be a VERY significant perf shortfall and depending on the startle factor versus reaction time is still in my view a possibility.
2) Low altitude capture. The HUD is very compelling and there is no visualisation of power demanded versus power set in the symbology. The speed tape has a 10 second speed trend arrow and the FPV has avery sensitive inertial speed trend arrow. Again recovery was possible but by this time the guys were ready for it.
3) I remain agnostic about the RAT deployment. However, aside from punching out the RAT on the overhead panel there was only one method we could find to deploy the RAT in this very short timescale.
hi Magplug.
regarding point 1).
how significant, would you care to expand ?

Subjects: RAT (All)  RAT (Deployment)

Bap7788
2025-06-19T20:21:00
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Post: 11906338
Lower than calculated lift at Vr

Hi all,

Sorry it’s going to be a long one but seeing the level of competency here, I though it would be the perfect place to get my answers. From the precious messages read and answers received, I have a scenario to run. I am more than happy to be told wrong from point 1). I don’t have the knowledge some of you do.

Please let me first start by saying that I am not trying to incriminate anyone. Hundreds of CRMS debriefs and accidents reports show us that unfortunately sometimes, the holes in that swiss cheese just do line up. It is far too easy for any of us, seating here, to judge any of the sequences happening in a Flight Deck. Mistakes happen, regardless of training and experience. We all do mistakes, every day, in every line of work.

DISCLAIMER:
I know that the consensus is a dual engine failure due to either TCMA bug or any sort of mecanical/software/wear and tear.
I do hear a RAT (I don’t see it though) and I do find the audio analysis quite compelling. It is at the top of my list as probable cause.
I am just exploring another scenario, based on the AC’s profile and state from grainy video and poor audio.

1- Let’s assume that we do all our perf calculation correctly. Is it possible that the OPT would spit up a F15/20 take off with the conditions on the day on a 787?
2- If so, let’s say we have performances for a F15/20 TO in the FMC. Now let’s assume we select F5 for TO (not in the FMC, physically). Would there be an FMC message, or would that trigger the T/O warning on the 787? If it doesn’t, we now potentially have an aircraft on the heavy side, with already a lift penalty on a high density altitude day.
3- Please bear with me, I know so far I have made an awful lot of suppositions and assumptions. Murphy’s law dictates that what can happen will happen albeit not on the same day. As it was answered to me by someone who was obviously seeing where I was going in a previous post, it’s a lot of swiss cheese to line up.
4- Take off roll goes on, Vr F15/20 comes and we rotate at a speed lower than we should for our actual F5 setting. My buddy calls for GEAR UP, I retract flaps to F1. Another lift penalty. Is there enough thrust now, or are we then already to deep on the back end of the drag curve ?

I do understand that this is not testable in a simulator. I am asking if someone with a 787 OPT and/or FCOM and knowledge views this scenario as possible or not (especially regarding the FMC message and the T/O warning). That is all.
thanks for the help !

Last edited by T28B; 19th Jun 2025 at 22:23 . Reason: formatting assistance

Subjects: Audio Analysis  Dual Engine Failure  Engine Failure (All)  FCOM  RAT (All)  TCMA (All)