bush_cheney2004 Posted January 5, 2015 Report Share Posted January 5, 2015 Cockpit flight control priorities are...aviate, navigate, then communicate. Quote Link to comment Share on other sites More sharing options...
Derek 2.0 Posted January 5, 2015 Report Share Posted January 5, 2015 Why no mayday call? Amybe the pilots knew they screwed up and tried to save face? ....or maybe they lost electrical power. Quote Link to comment Share on other sites More sharing options...
GostHacked Posted January 6, 2015 Report Share Posted January 6, 2015 If you remember the emergency landing on the Hudson-river a few years back that was considered as master-class piloting and that happened in a broad daylight on a placid river. Imagine trying the same in darkness on a stormy sea. In my days of trying to get my pilot's license, even a good cross wind on a flat surface in broad daylight can be challenging. Quote Link to comment Share on other sites More sharing options...
GostHacked Posted January 6, 2015 Report Share Posted January 6, 2015 (edited) ....or maybe they lost electrical power. This is why commercial aircraft have something called an Auxiliary Power Unit. It seems that early reports are saying that the pilots had requested to increase altitude. Possibly to avoid bad weather. Not sure who they would have talked to in order to make the request and if so, who would have denied the request? http://www.reuters.com/article/2014/12/30/us-indonesia-airplane-investigation-excl-idUSKBN0K812320141230 Among the early lines of inquiry is whether the crew could have asked to ascend, or climbed on their own initiative in case of emergency, at an earlier stage, and what role storms in the area might have played. "We know that the weather was very bad in this area, there was a storm," said the official, who declined to be named as he was not authorized to speak to the press. "Why did he (the pilot) request to climb at that stage? Should he have climbed earlier? Other aircraft were flying at a higher altitude in that area. How did the two pilots react to the weather? We are asking those questions." Edited January 6, 2015 by GostHacked Quote Link to comment Share on other sites More sharing options...
Derek 2.0 Posted January 6, 2015 Report Share Posted January 6, 2015 This is why commercial aircraft have something called an Auxiliary Power Unit. Yes, I know.......and more importantly, and likely with this case, a RAT. Clearly though, if all aircraft primary and emergency systems worked, all the time, their would never be crashes (absent 100% pilot error) Quote Link to comment Share on other sites More sharing options...
Wilber Posted January 7, 2015 Report Share Posted January 7, 2015 APU: Normally used for air conditioning and electrical power on the ground, not normally used in flight unless it is to provide backup power in event of an engine or generator failure. If both engines and generators were operating, the APU would not be started until after a failure occurred. A serviceable APU is not required unless for extended over water flights, which this was not. RAT: Usually provides electrical power for one pilots flight instruments and other basic electrical needs. Other pilots instruments will be powered by aircraft battery. in this case, it is likely that only one radio would be powered. Maybe they did try to make a distress call but could have done so on a dead radio due to the stress and high work load they would have been under. Who knows. STALL. There are several types of stalls with jet aircraft. An engine stall is a disruption of airflow through the engines compressor section. It can be quite dramatic with banging noises and flames from the turbine and fan exhausts. Sometimes the engine will recover on its own and others it can be shut down and restarted. It can also result in engine damage that results in failure. When speaking of "stalls" in turbine engines, they are not the same as engine failures. When it comes to aerodynamic stalls, a low speed stall is when the aircraft is not flying fast enough for its wing to generate enough lift to support its weight. You can GOOGLE high speed stall and coffin corner yourself because it would take too long to explain and others can do it better anyway. Until the DFDR and CVR are found and analyzed, everything is speculation. Quote Link to comment Share on other sites More sharing options...
Derek 2.0 Posted January 7, 2015 Report Share Posted January 7, 2015 RAT: Usually provides electrical power for one pilots flight instruments and other basic electrical needs. Other pilots instruments will be powered by aircraft battery. in this case, it is likely that only one radio would be powered. Maybe they did try to make a distress call but could have done so on a dead radio due to the stress and high work load they would have been under. Who knows. I would assume by providing electrical power to pumps/actuators for the aircraft's hydraulics? Also, with regards to the RAT, on civilian airliners, is it possible and/or standard to generate enough electrical power with a "feathered" turbine in an emergency? I know it was possible for older military aircraft like the Galaxy and Starlifters, but no longer sufficient with more modern fly-by-wire types like a Globemaster III with larger hotel loads. Until the DFDR and CVR are found and analyzed, everything is speculation. I agree 100%. Quote Link to comment Share on other sites More sharing options...
Wilber Posted January 7, 2015 Report Share Posted January 7, 2015 I would assume by providing electrical power to pumps/actuators for the aircraft's hydraulics? Also, with regards to the RAT, on civilian airliners, is it possible and/or standard to generate enough electrical power with a "feathered" turbine in an emergency? I know it was possible for older military aircraft like the Galaxy and Starlifters, but no longer sufficient with more modern fly-by-wire types like a Globemaster III with larger hotel loads. RAT's functions vary with aircraft. Some are just hydraulic and some are combinations of hydraulic and electric. Some four engine aircraft like the 747 don't have them at all. An engine driven hydraulic pump on a large windmilling turbofan will provide quite a bit of hydraulic power at normal flying speeds. The DC-10 used an ADG or air driven generator. It has a constant speed prop which allows the generator to produce 400 HZ, 110V power down to speeds of under 100 its. It can be selected to power either an electric hydraulic pump to provide basic flight controls or the first officers flight instruments. I'm not very familiar with the A320 RAT or feathering systems for turboprops. Quote Link to comment Share on other sites More sharing options...
On Guard for Thee Posted January 7, 2015 Report Share Posted January 7, 2015 I'll speculate if there was enough ice ingested to shut down the turbines then the wings etc. were loaded. Apparently there was a xponder at the last showing them at 36k and something like 105 hts. That sounds like a freezing pitot tube while possibly trying to outclimb the storm, although I can't understand why they would try and did they know how to calculate the heighth of a storm with the wx radar? Quote Link to comment Share on other sites More sharing options...
Derek 2.0 Posted January 7, 2015 Report Share Posted January 7, 2015 (edited) RAT's functions vary with aircraft. Some are just hydraulic and some are combinations of hydraulic and electric. Some four engine aircraft like the 747 don't have them at all. An engine driven hydraulic pump on a large windmilling turbofan will provide quite a bit of hydraulic power at normal flying speeds. I would assume with the 747, based on its similar vintage as a C-5, and the size of it engines, windmilling an engine would generate enough electrical power to sustain the hydraulics......... Ironically enough, a week before the Air Asia crash, in a conversation with a First Air 737 pilot on fixed wing versus rotary in-flight emergency procedures in the Arctic, I learned that the flight controls in a 737 can be operated without hydraulic pressure, with basic cabin electrical requirements being provided by batteries.......I would assume this not to be so with newer Airbus designs...... Edited January 7, 2015 by Derek 2.0 Quote Link to comment Share on other sites More sharing options...
Wilber Posted January 7, 2015 Report Share Posted January 7, 2015 I would assume with the 747, based on its similar vintage as a C-5, and the size of it engines, windmilling an engine would generate enough electrical power to sustain the hydraulics......... Ironically enough, a week before the Air Asia crash, in a conversation with a First Air 737 pilot on fixed wing versus rotary in-flight emergency procedures in the Arctic, I learned that the flight controls in a 737 can be operated without hydraulic pressure, with basic cabin electrical requirements being provided by batteries.......I would assume this not to be so with newer Airbus designs...... The main hydraulic pumps on all these aircraft are engine driven, not electric. Electric pumps are mainly used for ground operations so hydraulic systems can be pressurized without running an engine and as limited backups in flight. Older generation aircraft B707/727/737 do have manual reversion because they don't have the same hydraulic redundancy as new ones. The 707 used boost tabs for ailerons and elevators, only the rudder was hydraulic. These aircraft use electric backups for flaps and stabilizer trim. Flying a 737 without hydraulics is like steering your car when the power assist fails, maybe worse. Hard work but it can be done. Newer aircraft are all hydraulic, using at least three systems with at least two supplying each primary flight control, arranged so there will be some serviceable control surfaces in each axis if any two systems fail. Quote Link to comment Share on other sites More sharing options...
Derek 2.0 Posted January 7, 2015 Report Share Posted January 7, 2015 The main hydraulic pumps on all these aircraft are engine driven, not electric. Electric pumps are mainly used for ground operations so hydraulic systems can be pressurized without running an engine and as limited backups in flight. So in the event of multiple engine failures, could said hydraulic pumps also be air driven from the windmilling turbines? Quote Link to comment Share on other sites More sharing options...
Wilber Posted January 8, 2015 Report Share Posted January 8, 2015 So in the event of multiple engine failures, could said hydraulic pumps also be air driven from the windmilling turbines? They are unless the engine has seized. The hydraulic pumps, high pressure fuel pumps and generators are all driven by the engines accessory gearbox which is mechanically driven by the engines high pressure compressor section. If for some reason an engine is shut down or flames out in flight, it is not normally necessary to use the engines starter to get it going again. All that is needed is enough airspeed to reach a high pressure compressor rpm that will allow a restart to be initiated. For an aircraft at cruise altitude, a successful restart is highly likely if the engines are undamaged. All these aircraft have procedures for a loss of all engines and they are periodically practiced in simulators. Quote Link to comment Share on other sites More sharing options...
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