Posts by user "Capn Bloggs" [Posts: 48 Total up-votes: 193 Pages: 3]

Absolutely. I'm sorry if I implied that one should actually do the takeoff, between V1 and gear up, with your hands on the throttles. Definitely not.

Yes, we know it climbed. I suggested use of the granular data to show how high it was, in the context of the 400ft mode changeover point.

I don't have access to a current 787 manual, but have found a couple of unverified references to the VNAV engagement on the net. It appears the VNAV will engage at 400ft also. Happy to be corrected though.

Level-off point, approx 11sec after liftoff:
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Visually, it looks normal to me compared to other 787s I've seen takeoff. They don't point the nose to the heavens like most jets.

So a 787, loaded for a flight to London, does a normal takeoff roll (liftoff around 4000ft to run) but then tops out at 200ft because the TWO ENGINED thrust isn't enough to keep it flying (assuming there was no single-engine failure)? I don't think so.

Yes, 8sec from flight idle to max. So if it had enough thrust to get airborne normally, "TOGA" (your words) would have been available in an instant because the engines would have been running at only a few % below max thrust anyway. There would be no waiting time. If those engines had been running, the crew could have recovered from that descent easily right up until the last second by firewalling the throttles.

Agree. The two most important controls in the aeroplane, sitting there in a wide-open, unprotected space. After an incident where a manual fell off the coaming (can't remember if a switch got bashed into the Off position), we put guards on our non-787 fuel switches:
Ours:

787:

LB, do a thread search for "195".

Come on, people. If it went into altitude hold, yes, the power probably would come off, but only to maintain the current airspeed. It would very quickly start powering back up as the aircraft attempted to sink and was countered by the PF. But the power didn't come back up, that being obvious from the increasing AOA during the descent.

In any case, there wouldn't be a sudden level-off because the PF is still l hand flying below 200ft. Do you think he'd blindly just jam the stick forward to follow the FD at such a low altitude?

As stated before, if even only one of those engines was running, there's no way it would have descended, slowing down, as it did.

And then there is the issue of the gear. If this whole thing was simply a case of a low-altitude level off, why was the gear not retracting/up? The very first thing the PM does, within a second of leaving the ground, is call "Positive Rate". I cannot believe that something (eg FD commanding ND) associated with a low-alt level off could have distracted the PM or the PF so much that they forgot the gear.

Yes, and probably much to @Roo's disgust, we had an instance where an engine shut down all by itself in the cruise; it was concluded that the fuel switch hadn't been "locked" in the ON position and was just sitting on the edge. It was then highlighted to all of us that the FCOM stated "give it a good jiggle" to make doubly sure it was locked in ON.

Here we go again.
They are not "ground-only" levers, Why do you and MagPlug have this idea that the PF would not place their hand back on the thrust levers after the gear up call, or at least be guarding the throttles just in case, heaven forbid, they started to roll back?

That would be a stupid design. FYI, the old 787 FCOM I have says "Maximum rated thrust is available in any phase of flight by moving the thrust levers to the full forward positions".
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Irrelevant. They were doing a single-engine test and completely messed it up; nothing like what this crew would have been faced with. They were ta Idle because the captain pulled the TL back in an attempt to regain control. Nothing like you say.

I'd suggest not but the elephant in the room as far as you and Magplug goes... what are the pilots doing all this time? Just sitting there watching?

That is not a Boeing Fuel switch.

The RAT (unverified source):

Obviously. If yours is the switch I think it is (with the metal, unscrewable dome) then yes, it is very different. Very hard to "balance" yours in the middle.
Not so the Boeing fuel switches: they can be relatively easily "sat" in the middle, on the centre raised bit and could be bumped either way. Hence our (non-787) FCOM saying make sure you jiggle them when you put it in the On position to confirm it's locked there.

I can vouch for that. It was easy to tell whether a switch was "new" or "old" because it was easier to get out of a position because of the slightly rounded edges on the older ones. I say "easier" because when properly in OFF or ON, the switch was still quite secure and couldn't be moved, regardless of age.

That's why Boeing put side guards on the panel.

The bleeding obvious didn't work on the Jeju Air 737.

The 787s recorder/s have obviously been damaged so much/missing data they are being taken to the US.

In this case, not being a 787 jock, my WAG would be a V2 of 165, so they'd be at ~180, and Vref would be at least ~160 (422,000lb, at flap 5). Once those engines cut, it wasn't going much higher at all. Bit of a zoom of possibly 100ft max, IMO. So I doubt the engines stopped at liftoff.

Having done many a takeoff sitting with the nose pointed skyward after liftoff, you just know that if both engines stopped, you would almost immediately stop going up. When you lose only one you have to be quick getting the nose down to keep the speed. If you lost both, you're not going much higher.

Disclaimer: the numbers I mention are from publicly available sources, namely Wiki (for the ZFW weight calculation) and a Boeing FCOM dated 2010, and my own estimations.

IMO, if those engines failed just after rotation, there is no way that jet would have got anywhere near 200ft, especially if the fuel was "cut off", as opposed to back to Idle.

At 420k lbs (310k lb ZFW+110k lb Fuel), the (takeoff) V2 Flap 5 is 157kts. The (landing) Vref for Flap 5 I estimate to be at least 160kts (the FCOM I have has no figures for Flap 5 landings; F20 Vref is 154; the manoeuvre speed for Flap 5 is 189). Typically, you'd probably be at V2+15 when you get established in the climb after rotation.

No. With a pitch attitude of around 15\xb0, that's quite a bit of weight being supported not only by the wings but by the engine thrust vector. Cut that and you stop going up very quickly. Note Sailvi's comment above.

ANY reduction in pitch attitude would cause the climb to cease immediately. These aircraft are going so slowly, relatively, and the drag is so high that any small change in pitch attitude will cause an increase in descent rate with very little increase in speed (or no lessening of deceleration).

Not IMO. Basically, the only reason this jet is flying is because of the whopping long thrust vector out the back. It's already almost back at minimum speed anyway for flap 5 so there is very speed to trade. In this case, I wouldn't be trading anything, because the speed reduction rate would be too fast.

My estimate is around 200ft (one wingspan) and I hypothesise the engines were producing plenty of thrust until about 7 seconds, before it stops climbing at around 12 seconds after liftoff.

@Brace , I think you're exaggerating the residual thrust effect at lower RPMs. Of course 70% would get you round the pattern but you're at a much lower drag config and you're going much faster, again less drag. And are improved-climb takeoffs in the 787-8 even a thing? I can't see a two-stage rotation.

I've made up a YT combo video:

What would be the point? The speed wouldn't increase and more relevant, they are only a couple of hundred feet off the ground. Lowering the nose will just shorten the flight time and mean you hit the ground harder.

Looking at the video, I think the actual flying was superb: they stretched it as much as they could without stalling it. Such a shame that they ended up in buildings. If it had been anywhere else, there would have been many more survivors IMO.

I would take that post by Crossky with a grain of salt. No part of his post made sense and I can only assume he is not a 787 pilot despite claiming to be. "Fuel starvation if pumps aren't turned off, not in my manual but I read about a procedure on the Internet", it's loony stuff.

Your comment:
Is correct. As commented by Sailvi767, only after the jet is cleaned-up, away from the ground and ATC sorted out would any "normal" defect that didn't require a Memory/Recall item be attended-to. Now, if both engines stopped 7 seconds after liftoff, that's different; there is no published procedure for that.