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Comment: Re:Umm, no... (Score 1) 449

by David Horn (#36276124) Attached to: Flight 447 'Black Box' Decoded

PF: Pilot flying.
PNF: Pilot NOT flying
TOGA: Take off / Go around power. Layman's terms, "firewalling it".
Normal Law: Sidestick commands load factor (ie, "G") and roll rate. High speed / low speed / bank angle / stall / load factor protection.
Alternate Law: Arrived in this state due to system degradation. Numerous causes. Not really an issue. Sidestick commands load factor, however, direct control of ailerons. No protection other than load factor and stability at high / low speeds. Aircraft can be stalled.
Direct Law (reference): Sidestick directly commands elevator and aileron position. Aircraft enters this law with gear down and autopilot disconnected.

Useful reference:
http://www.airbusdriver.net/airbus_fltlaws.htm

Comment: Re:Umm, no... (Score 1) 449

by David Horn (#36274386) Attached to: Flight 447 'Black Box' Decoded

Recovering from the approach to stall in alternate law was certainly part of my training for the A320, and at no point was it even suggested that it involved back-pressure on the sidestick or full thrust in an attempt to "power out" of the stall. Normal stall recovery is to reduce the angle of attack and then carefully increase power once the aircraft is out of the stall.

The ability to perform what might be considered extreme manoeuvres in normal law is something which a pilot will deliberately choose to do. Examples in which we'd expect to use the flight envelope protection include windshear, TCAS, and (E)GPWS events; not speed discrepancies. If the aircraft is shouting "STALL, STALL" at us, I don't know ANY pilot who would pull back or fail to respect the warning.

Comment: Re:Umm, no... (Score 1) 449

by David Horn (#36274324) Attached to: Flight 447 'Black Box' Decoded

Not in this case, though. The aircraft remained in the nose-high attitude due to continuous back-pressure applied by the PF, probably unknown to the PNF. The Airbus's flight characteristics exacerbated the situation by applying nose up stabiliser trim to neutralise elevator deflection. This is not unique to the Airbus; any modern jet transport aircraft will do the same but it doesn't help, since it reduces nose down pitch authority.

Quite correctly, in normal law the Airbus cannot be stalled. That doesn't mean it can't be crashed. However, in alternate law it can certainly be stalled. The warning - which is aural, continuous, and unmistakable: "STALL... STALL..." - signals the approach to the stall and a recoverable situation at any point in the flight envelope. Applying TOGA power would make the situation worse by inducing a nose-up pitching moment, although I doubt that at 35,000ft there was sufficient excess thrust to make a significant impact. It would certainly be noticeable at lower levels.

I do not know - and doubt we will ever know - the reason why nose up sidestick inputs were made. However, I imagine the A350 series will have back-driven sidesticks as a direct result of this accident.

Comment: Re:email? (Score 1) 306

by David Horn (#31631366) Attached to: College To Save Money By Switching Email Font

For OLED, the true best case scenario for low power usage is green text on a black background. This is because an OLED isn't a true RGB pixel layout. Instead, it typically runs RRGBB, with the red and blue pixels double sized for apparent longevity reasons.

The green pixel is half the size, so presumably half the power usage.

And I'm perfectly aware I've just pointlessly wasted 5 minutes of my life writing that. APPRECIATE IT, SLASHDOT. :-)

Comment: Missing option - Tommy Flowers (Score 2, Interesting) 737

by David Horn (#31436362) Attached to: What IT pioneer do you respect the most?

The true computing pioneer was Post Office engineer Tommy Flowers, who designed Colossus, the world's first programmable electronic computer.

After the war Flowers was granted £1,000 by the government, payment which did not even cover Flowers' personal investment in the equipment. His work in computing was not fully acknowledged until the 1970s because the project was restricted by the Official Secrets Act.

Comment: Re:UK citizen? (Score 4, Insightful) 571

by David Horn (#30240662) Attached to: Hacker McKinnon To Be Extradited To US

People have an issue with this because if convicted in America he will face the rest of his life (however long or short it may be) languishing in a high security American prison. In the UK we do at least give the majority of our prisoners the chance of rehabilitation.

The above comment disregarding the fact that a US jury is almost certainly likely to be biased against a foreigner; his inability to qualify for any capable legal aid; and an unfamiliarity with the US legal system seems to me an excellent reason to allow him to be tried at home. I imagine that they're also looking to try him under a terrorism-related charge, which is patently not what he set out to achieve.

However, this is now boiling down to a deeper issue of a massive disparity between the number of people extradited from the UK to the USA and vice-versa. I daresay the bulk of this is due to the fact that we do in fact harbour more potential terrorists, but at least some part of it is due to a government that just rolls over and takes it up the arse.

Comment: Re:Suspect?.... (Score 3, Informative) 403

by David Horn (#28512585) Attached to: Investigators Suspect Computers Doomed Air France Jet

Coffin corner does not refer to a simple underspeed/overspeed condition. Limiting factor for speed at high altitude is Mach number, not IAS. Exceeding Mcrit leads to shockwave formation on the leading edge of the wing. This moves the centre of pressure rearwards and causes an uncontrollable nose-down pitching moment known as Mach Tuck.

It is this that can cause speeds to rise to the point where they're damaging to the airframe.

At coffin corner, slowing down will give pre-stall buffet, while speeding up gives mach buffet, the precursor to mach tuck. It's almost impossible to tell the difference between the two. Additionally, given the high TAS even small control inputs can have very rapid and extreme effects. It is exceptionally difficult to hand-fly an airliner at high altitude, especially without the benefit of automatic trim.

Software

+ - Vista - Ubuntu Install Comparison

Submitted by
Cokeisbomb
Cokeisbomb writes "Andrew Thomas, at the Inqurier has recently installed both Vista and the latest version of Ubuntu on his desktop and has compared the install process and initial setup. Although he has been using computers for 30+ years, his findings were different than what many of us might expect. From the article: "Well, I've only been playing with computers since 1972 and I couldn't make it work. Linux can see the Windows boxes and vice versa, but any attempt to access files is met with a login dialogue box that refuses any username and password I enter. So I've done what any normal person would do in the circumstances — give up"."
First Person Shooters (Games)

+ - Call of Duty 2 for Pocket PC

Submitted by
An anonymous reader writes "Six years ago we got PocketQuake. Since then, the Pocket PC has seen Tomb Raider, Worms, DoomGL, and numerous emulators. The latest big budget title to hit the Windows Mobile scene is Call of Duty 2, a direct port from the original and featuring OpenGL-ES support for the Dell X50v line of PDAs. The game was ported by Aspyr (the Mac games developers), and there's an exhaustive review (also in PDF, no ads) at PocketGamer.org."

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