NTSB probable cause of the accident was UAV pilot's failure.

[alph2z]

Washington, DC - As a result of its first investigation of an accident involving an unmanned aircraft (UA), the National Transportation Safety Board today issued a total of 22 safety recommendations to address what NTSB Chairman Mark V. Rosenker said were "a wide range of safety issues involving the civilian use of unmanned aircraft."


The Safety Board determined that the probable cause of the accident was the pilot's failure to use checklist procedures when switching operational control from a console that had become inoperable due to a "lockup" condition, which resulted in the fuel valve inadvertently being shut off and the subsequent total loss of engine power, and a lack of a flight instructor in the Ground Control Station.

"This investigation has raised questions about the different standards for manned and unmanned aircraft ......

alph2z>> Cool, the same lever controls fuel valve and camera iris, depending on console status.

Imagine doing an engine out fuel emergency on an airliner, and while playing with the fuel valve lever you realise that it's actually controlling the camera's iris (until the proper console is selected). This adds another significance to the age-old fuel valve problems that have occurred since the beginning of aviation.

I can see the NTSB looking at a recorded video of an airliner incident (or the passengers' outside view on their monitors) and seeing that the exposure on the video continually shifts from over- to under-exposed -- over and over......

.....two nearly identical pilot payload operator (PPO) consoles, PPO-1 and PPO-2. Normally, a certified pilot controls the UA from PPO-1, and the camera payload operator (typically a U.S. Border Patrol agent) controls the camera, which is mounted on the UA, from PPO-2. Although the aircraft control levers (flaps, condition lever, throttle, and speed lever) on PPO-1 and PPO-2 appear identical, they may have different functions depending on which console controls the UA.


When PPO-1 controls the UA, movement (of) the condition lever to the forward position opens the fuel valve to the engine; movement to the middle position closes the fuel valve to the engine, which shuts down the engine; and movement to the aft position causes the propeller to feather. When the UA is controlled by PPO-1, the condition lever at the PPO-2 console controls the camera's iris setting. Moving the lever forward increases the iris opening, moving the lever to the middle position locks the camera's iris setting, and moving the lever aft decreases the opening. Typically, the lever is set in the middle position......


Although the aircraft control levers (flaps, condition lever, throttle, and speed lever) on PPO-1 and PPO-2 appear identical, they may have different functions depending on which console controls the UA.


http://www.ntsb.gov/ntsb/brief2.asp?ev_id=20060509X00531&ntsbno=CHI06MA121&akey=1
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[Airbubba]

Looks like the consoles were designed without much thought about human factors. In the "locally" piloted aircraft, if it looks like a flap lever it had better be a flap lever or the feds will never buy it.

Several large cargo operators have been quietly exploring the possibilty of remotely piloted ships and planes for years now. Remember when all the ALPA contracts had sunset provisions for the flight engineer? Maybe something similar can be worked out for the pilots in the years to come. :)

[barit1]

UA Control System

The accident UA was operated by means of C-band (signal communications), which provided for LOS control. The UA descended below LOS after the engine stopped producing power.

A secondary means of control was provided through the Iridium satellite communication system. However, in the Iridium control mode, there is limited ability to control the UA; under Iridium control, the only way to control the UA is by using autopilot hold modes. All hold modes (altitude, airspeed, and heading) must be active for the Iridium satellite to control of the UA. The hold modes were on before the lost link. If both the Iridium and LOS uplinks are active, the LOS link has priority, and the Iridium data is ignored. However, when the fuel was cut off to the engine and the UA began shedding electrical equipment to conserve battery power, the Iridium system was one of the items that was shed. The UA is also equipped with an auto-ignition system, but this system will not work unless the Iridium system is operable.

This reads like a comedy of errors in the design cycle of the Predator. The FMECA (Failure Modes, Effects, & Criticality Analysis) has more holes in it than Swiss cheese.

[ATC Watcher]

This would be a good comedy script indeed if the UAV did not cost tens of millions USD and will not eventually fall in a populated area or hit another aircraft in the descent .
However, when the fuel was cut off to the engine and the UA began shedding electrical equipment to conserve battery power, the Iridium system was one of the items that was shed.

If it switched off the satellite link, I wonder if the UAV transponder is one of the items that will be "shed" as well , same with the Tcas-like unit they are supposed to carry.

[rodthesod]

Ah, so maybe someone pressed the wrong button on 9/11 and launched a cruise missile at the pentagon instead of launching fighters to intercept hijacked airliners.

Stupid I know, but a lot more plausible than most of the 'official' versions of what happened.

:E

[barit1]

Sorry - but I don't see this as pilot error at all. For a system as sophisticated and (ostensibly) mature as Predator to have such a human factors issue points the arrow of probable cause back to the designers.

No certificated manned aircraft would have such an ambiguous control system. There are good reasons cockpits of manned aircraft are standardized, and an unmanned aircraft with a 66' wing is no less a hazard to other aircraft (or to persons on the ground) than a manned one the same size.

And so yes, the pilot was in error, but he had a LOT of help. :ugh: