|Quoting nm2582 (Reply 88):|
Would there be any benefit to altering the stick shaker logic, such that it uses some kind of "look ahead" algorithm? If you take current airspeed, attitude, and configuration (flap setting, power setting, gear up/down, etc.) you can predict many seconds into the future when the aircraft would be on the threshold of stall. You also know the current power setting and how long the engine takes to spool up from the present power setting; so you can determine how much warning is needed to accommodate the engine spool up time. Essentially, the logic would be: "if engine spool-up time plus some safety factor is greater than the time to stall in current config, then activate the stick shaker".
This idea is predicated upon my assumption that stick shaker logic is fine at altitude (if you encounter the shaker at 15,000 ft, ease up on the stick, gain some speed, and you're fine) but perhaps not quite enough warning on final.
In theory, sure. However I think the number of false alarms you get would be large. The positional precision required is very high if nothing else, and GPS
is not quite as magical as most people think. There can be errors.
You also risk confusing pilots.
IMHO, pilots have plenty of tools to warn them already. If those tools aren't giving them a hint, they are not going to listen to one more warning. Look at what happened to AF447. Plenty of information available that would have helped the crew, but they consistently discarded it since it did not support their hypothesis.
|Quoting ABpositive (Reply 91):|
Why not place the camera in the cockpit and store data in the VDR box. This way there is audio and video evidence for investigators and cameras are small enough now to be placed in cockpits unobtrusively.
The DFDR and CVR already give lots of info. This would seem quite intrusive. Given that airlines already use data to nail pilots who don't perform, what could they do with this? At least that's what pilot reaction to this sort of plan has been to date.
|Quoting Aesma (Reply 81):|
I think it's not about the attitude but about the gear, you don't retract it while you're still descending, since it might be needed to bounce off the runway.
Typical procedure would be to initiate a go-around and ask for gear up and the first notch of flaps. The pilot monitoring would retract the gear, but importantly ensure first that rate of climb was positive in case the plane sinks so much it hits the runway.
|Quoting cloudboy (Reply 2):|
We know low speed was a critical factor in this crash. Media reports make it sound like the aircraft was so slow that it was nearing stall speed - is that the case? We know it is well below normal landing speed, but the aircraft was not in, nor was it even near, stall speed, correct? I
Vref, the reference speed to be used on final until crossing the threshold, is Vs0 (stall speed in landing configuration) times 1.3, at least in a low-wind situation with a clean runway. Given Vref as 137, stall speed was 105. They were at stall speed. Also, even just above stall speed the controls start to get very mushy and the plane feels sluggish due to low and disturbed airflow. If you pull up at these speeds, even if you don't get a clear stall, the plane will not change direction but just keep on going..
|Quoting cloudboy (Reply 2):|
If that is the case, from a pilots point of view, how much weight do they place on airspeed vs approach angle and rate of descent while landing?
That stuff is of paramount importance.
|Quoting Braniff747SP (Reply 3):|
Apparently the stick shaker went, so that would point the airplane to being right above stall speeds.
Indeed. The stick shaker will activate at least 5% above stall speed.
|Quoting cloudboy (Reply 5):|
Where were the relief pilots at the time? We're they actually in the cockpit at the time, or were they upstairs in the rest cabin.
If they weren't in the cockpit, they were probably in jump seats of pax seats. The crew rest might well not be certified for occupation during take-offs and landings.
|Quoting moderators (Thread starter):|
Amazing stories. Hopefully helps dispel the notion that Asian carrier FAs overly focused on service and not sufficiently trained on safety. Service and safety are not mutually exclusive. These FAs are heroes!
Quite right. I recall stories about SQ006 flight attendants running back into the burning plane to save pax, including Irene Ang, who died while doing so.
Quoting slider from thread 6
LH was saying that the steep glide slope was due to potential noise restrictions and it leads their locations for aborted landings.
The glide slope is a bog-standard 3 degrees.
Quoting frmcapcadet from thread 6
Also would the pilot at the last few seconds nosed up to avoid a head-on collision with the seawall? This would seem to be a desperate but correct move??
A desperate and incorrect move. At such low speeds on the back of the drag curve all pulling up does is change the pitch angle without changing the flight path angle. The only way to extend the glide is to pitch forward since best glide speed (for longest glide) is faster.
Quoting frmcapcadet from thread 6
But this plane was sinking at a faster rate than SOP IIRC, so it what point should they have increased engine power, and how many seconds would it take to recover altitude?
There's a reason DH
for a full ILS is 200 feet AGL. It takes a while for the engines to spool up as you say. However more importantly the go around procedure assumes the speed is around Vref. If the speed was 20 knots below you'd need way more height, I'm guessing a couple hundred feet.
Quoting zkojq from thread 6
they deserve every cent of their pay check. Probably a promotion too. And they did all this while wearing reasonably low skirts which I thought would be impossible to run/climb over stuff in (are these factors considered when the uniform is designed?).
Presumably. In any case skirts cannot be too restrictive in normal service either since F/As do a lot of squatting and bending over during meal service.
Quoting flyingturtle from thread 6
What are the advantages/disadvantages of having the autothrottle on during a visual approach?
Reducing workload? Can one simply aim for the touchdown point (while respecting a healthy sink rate, though), while the autothrottle just cares about the right airspeed?
Reduced workload indeed. Let the autothrottles worry about airspeed.
|Quoting tp1040 (Reply 44):|
The ILS was out of operation and the effect , if any, on the events is not yet obvious.
Not really germane to the crash, is it common for it to out at a major airport for such a long time.???
I know there are different systems in place to safely land a plane, but the ILS being out of service makes it one less tool a pilot has to safely land a plane. Seems like an unnecessary risk and poor management by the FAA and the airport. As flier, I want all the resources available, up to date and working.
It is not uncommon. It was only out on that one runway. Also, on a clear day the ILS should not be needed by a trained pilot. It doesn't really add to risk if it isn't there.
[Edited 2013-07-09 17:27:08]
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo