Pilot Position induced errors.

[scifi]

Having watched the discussion on the 777 at DXB accident, I wonder if the Piloting Position (at the front of the plane.) could have been a contributory factor. The Static Vents and Pitots are also located up-front.
So although the front is going up, the wing may not be climbing, and the rear of the plane is actually descending.


I had a working Vertical Speed Indicator (VSI) in my car, and can confirm that even a change of height of 5-10 feet can give a large positive reading.
By pitching 15 degrees nose up, the flight crew would initially feel as if the aircraft was climbing, unless they could fly the aircraft from the rear seats, in which case their initial thoughts would be that they were descending.

[mustangsally]

The position of the sensors has very little to do with this accident. Much more to do with crew training and crew resource management. We don't have all the details, that may take over a year. But, on a rejected landing after touch down, the spoilers having had ground contact want to extend. This is prevented by advancing the thrust levers. Whether the TOGO switch was selected or not the pilot flying must back the system up and advance the thrust levers manually. The non flying pilot must confirm the trust levers are advancing and that we have two indications of climb, both VVI and altimeter. Then the non-flying pilot calls positive rate and the flying pilot call gear up. At maximum landing weight, with both thrust levers advance even close to go-around thrust, the aircraft climbs very quickly.


Sorry, but you are just barking up the wrong tree.

[Mad (Flt) Scientist]

With regard to the OP.

it must be borne in mind that in the process of certifying an aircraft, things like go-arounds and other manoeuvres are conducted and the various systems must be shown to work appropriately (meet their "intended function" is a typical phrase used). The test pilots are also assessing the handling of the aircraft in its broadest sense, and they are of course sat where the line pilots will eventually end up. So any effects of position on perception, say, or of sensor position on sensor accuracy will in fact be investigated during test and if necessary adjustments made (either to the system desitgn or to relevant procedures, or both)

that's not to say that things like sonomatagraphic illusions are not an issue in specific cases, but that the basic effect of the aircraft design is taken into account during design approval.

[Fursty Ferret]

Not sure about the 777 but VSI is generally combination of inertial and barometric. That's why the call is "positive climb" (in general), not "positive rate".

[oggers]

I had a working Vertical Speed Indicator (VSI) in my car, and can confirm that even a change of height of 5-10 feet can give a large positive reading. By pitching 15 degrees nose up, the flight crew would initially feel as if the aircraft was climbing

During rotation a VSI will if anything indicate a descent.

[Capn Bloggs]

For goodness sake, I thought this was a professional pilots forum?? Mods!

[scifi]

oggers.... During rotation a VSI will if anything indicate a descent.


That doesn't seem very likely, if the static port is rising, the instrument should indicate a positive rate of climb, even if the airplane's CofG is still going down.

[Centaurus]

Then the non-flying pilot calls positive rate and the flying pilot call gear up

Many times I have observed in simulator training the PM anticipating calling "positive rate" when his altimeter hasn't moved and always the PF then calls "gear up" as a reflex. Monkey see - monkey do, syndrome.

You can see this coming when you see the PM moving his hand towards the gear lever before calling "positive rate"

Far better the PF calls positive rate first - waits for the PM to confirm - then the PF calls "gear up".

[Denti]

Many times I have observed in simulator training the PM anticipating calling "positive rate" when his altimeter hasn't moved and always the PF then calls "gear up" as a reflex. Monkey see - monkey do, syndrome.

Not a trainer myself, but that is one of the things that is a constant pain in the behind. PFs calling "gear up" before the PM calls "positive climb" and most are in a big hurry to get the gear up.

I was tought from the start of my career in a jet to check for three things before calling positive climb: baro altimeter counting up, radio altimeter doing the same and IVSI positively indicating a climb. Some just see the horizon dropping and think they are climbing when in fact they are simply rotating. The end result is someone putting the gear up while still on the ground, see for example the luxair case in Saarbrücken. Or putting the gear up in a go around before an actual sustained positive rate is achieved.

[vapilot2004]

The Static Vents and Pitots are also located up-front.
So although the front is going up, the wing may not be climbing, and the rear of the plane is actually descending.

Pitots and static ports are up front for a reason - it is an area of the aircraft that is most assured to receive unimpeded (and unmolested) airflow. The location of the probes and ports is specific to the aircraft. While your personal VSI may be interesting to use while driving up and down hills, the IVSI as installed on an aircraft involves tens of thousands of dollars of equipment, and likely well over a hundred thousand dollars worth of engineering and research to get it just right for that aircraft.

The IVSI uses information not only from the static ports, but also has inertial inputs from the IRUs for presenting the most accurate and instantaneous information. While there may be some bouncing about and damping during turbulence, for all other phases of flight, these things are very accurate and fast.

[oggers]

scifi

That doesn't seem very likely, if the static port is rising, the instrument should indicate a positive rate of climb, even if the airplane's CofG is still going down.

The dip of the VSI during rotation is a known phenomenon arising from the change of airflow around the static port. I can't list which types get it and which don't but with the basic pressure instrument it's not as simple as 'the nose went up therefore a climb is indicated'.