From: Brimstone on 18 Jun 2008 14:46
> Brimstone wrote:
>> Eeyore wrote:
>>> Brimstone wrote:
>>>> Hiram wrote:
>>>>> "Brimstone" wrote:
>>>>>>> The point I'm trying to make is - flying an aircraft is harder
>>>>>>> than driving a truck. Much harder.
>>>>>> How so, are there idiots in small runabouts, traffic lights,
>>>>>> roundabouts and pedestrians with a death wish at 10,000 ft as
>>>>> OK, let me specify something here.
>>>>> Flying an aircraft is 'intellectually' harder than driving a
>>>>> Happy now?
>>> How so ?
>> If flying was more intellectualy challenging than driving a road
>> vehicle then we wouldn't have computers controlling aircraft.
> The tortured logic behind that concept has left me baffled.
Glad to know that my efforts weren't wasted. :-)
> Are you saying for example that truck drivers would be better drivers
> if they had no cruise control ?
Cruise control doesn't steer the vehicle. Auto-pilot does.
> Do you not also realise that a heck of a lot of that cockpit
> automation was put there to get rid of the flight engineer in one
> respect and to reduce pilot workload with routine 'stuff' so as they
> could concentrate better on flying the plane ?
AIUI autopilot was devided so that the pilot/s don't have to make minor
adjustments throughout the flight to keep the a/c on track and at the
> Oh, and to keep fuel
> costs down.
That's a more recent added bounis I would suggest.
> All so you can fly to wherever for �25.
Err, no. Autopolit has been around a lot longer than that, although I accept
has been refined and added to over the years.
From: Eeyore on 18 Jun 2008 15:02
> If flying was more intellectualy challenging than driving a road vehicle
> then we wouldn't have computers controlling aircraft.
No, that makes no sense at all.
Let me remove the negatives and superfluity. You effectively said
" If flying wasn't more challenging than driving a road vehicle
then we would have computers controlling aircraft. "
And we DO have computers controlling major aspects of aircraft operations.
Right down to the automatic fuel control to maintain engine speed / EPD via
FADEC. So my point is made.
The pilots are there to 'tell' the computers what to do (i.e to actually fly
the aircraft using the control interface like the control wheel / sidestick,
throttles etc and lets the computers do the basic 'housekeeping' like
ensuring all the temps and pressures are correct and keeping a specific
course if so demanded) and take over if they break.
A FADEC is a system consisting of a digital computer, called an Electronic
Engine Control (EEC) or Electronic Control Unit (ECU), and its related
accessories that control all aspects of aircraft engine performance. The
term FADEC is an acronym for either Full Authority Digital Engine Control or
Full Authority Digital Electronics Control. FADECs have been produced for
both piston engines and jet engines, their primary difference due to the
different ways of controlling the engines.
The goal of any engine control system is to allow the engine to perform at
maximum efficiency for a given condition. The complexity of this task is
proportional to the complexity of the engine. Originally, engine control
systems comprised simple mechanical linkages controlled by the pilot. By
moving throttle levers directly connected to the engine, the pilot could
control fuel flow, power output, and many other engine parameters.
Following mechanical means of engine control came the introduction of analog
electronic engine control. Analog electronic control varies an electrical
signal to communicate the desired engine settings. The system was an evident
improvement over mechanical control but had its drawbacks including common
electronic noise interference. This system was pioneered in the 1960s and
first introduced as a component of the Rolls Royce Olympus 593 engine. The
593 was the engine of the supersonic transport aircraft Concorde.
Following analog electronic control, the clear path was digital electronic
control. Later in the 1970s NASA and Pratt and Whitney experimented with the
first experimental FADEC, first flown on an F-111 fitted with a highly
modified Pratt & Whitney TF30 left engine. The experiments led to Pratt &
Whitney F100 and Pratt & Whitney PW2000 being the first military and civil
engines respectively fitted with FADEC and later the Pratt & Whitney PW4000
as the first commercial "dual FADEC" engine.
True full authority digital engine controls have no form of manual override
available, placing full authority over the operating parameters of the
engine in the hands of the computer. If a total FADEC failure occurs, the
engine fails. If the engine is controlled digitally and electronically but
allows for manual override, it is considered solely an Electronic Engine
Control or Electronic Control Unit. An EEC, though a component of a FADEC,
is not by itself FADEC. When standing alone, the EEC makes all of the
decisions until the pilot wishes to intervene.
FADEC works by receiving multiple input variables of the current flight
condition including air density, throttle lever position, engine
temperatures, engine pressures, and many others. The inputs are received by
the EEC and analyzed up to 70 times per second. Engine operating parameters
such as fuel flow, stator vane position, bleed valve position, and others
are computed from this data and applied as appropriate. FADEC also controls
engine starting and restarting. The FADEC's basic purpose is to provide
optimum engine efficiency for a given flight condition.
FADEC not only provides for efficient engine operation, it also allows the
manufacturer to program engine limitations and receive engine health and
maintenance reports. For example, to avoid exceeding a certain engine
temperature, the FADEC can be programmed to automatically take the necessary
measures without pilot intervention.
With the operation of the engines so heavily relying on automation, safety
is a great concern. Redundancy is provided in the form of two or more,
separate identical digital channels. Each channel may provide all engine
functions without restriction. FADEC also monitors a variety of analog,
digital and discrete data coming from the engine subsystems and related
aircraft systems, providing for fault tolerant engine control.
To perhaps more clearly illustrate the function of a FADEC, explore a
typical civilian transport aircraft flight. The flight crew first enters the
data appropriate to the day�s flight in the flight management system or FMS.
The FMS takes environmental data such as temperature, wind, runway length,
runway condition, cruise altitude etc. and calculates power settings for
different phases of flight. For takeoff, the flight crew advances the
throttle (which contains no mechanical linkage to the engine) to a takeoff
detent or opts for an auto-throttle takeoff if available. The FADECs know
the calculated takeoff thrust setting and apply it. The flight crew notes
that they have merely sent an electronic signal to the engines, no direct
linkage has been moved to open fuel flow. This procedure is the same for
climb, cruise, and all phases of flight. The FADECs compute the appropriate
thrust settings and apply them. During flight, small changes in operation
are constantly being made to maintain efficiency. Maximum thrust is
available for emergency situations if the throttle is advanced to full, but
remember, limitations can�t be exceeded. The flight crew has no means of
manually overriding the FADECs, so if they make a decision the crew doesn�t
like, it will have to be accepted.
FADECs today are employed by almost all current generation jet engines and
increasingly in newer piston engines, on fixed-wing aircraft and
In piston-engine powered aircraft, the system replaces both magnetos, making
obsolete repetitive and costly magneto maintenance, and eliminates
carburetor heat, mixture controls and engine priming. By controlling each
cylinder of the engine independently for optimum fuel injection and spark
timing, the need for the pilot to monitor and control mixture is eliminated.
Because imprecise mixture operation can affect engine life, the FADEC has
the potential to reduce operating costs and increase engine life for the
average General Aviation pilot. Tests have also shown significant fuel
savings potential. FADEC paid for itself in reduced operating costs.
Better fuel efficiency
Automatic engine protection against out-of-tolerance operations
Safer as the multiple channel FADEC computer provides redundancy in case of
Care-free engine handling, with guaranteed thrust settings
Ability to use single engine type for wide thrust requirements by just
reprogramming the FADECs
Provides semi-automatic engine starting
Better systems integration with engine and aircraft systems
Can provide engine long-term health monitoring and diagnostics
Number of external and internal parameters used in the control processes
increases by one order of magnitude
Reduces the number of parameters to be monitored by flight crews
Due to the high number of parameters monitored, the FADEC makes possible
"Fault Tolerant Systems" (where a system can operate within required
reliability and safety limitation with certain fault configurations)
Can support automatic aircraft and engine emergency responses (e.g. in case
of aircraft stall, engines increase thrust automatically).
Engineering processes must be used to design, manufacture, install and
maintain the sensors which measure and report flight and engine parameters
to the control system itself.
Software engineering processes must be used in the design, implementation
and testing of the software used in these safety-critical control systems.
This requirement led to the development and use of specialized software such
From: Eeyore on 18 Jun 2008 15:13
> > Exactly so, but both a/c rely on the same basic priciples to operate. The
> > 747 merely has more switches and button etc to operate and thus more to go
> > wrong.
> And the extra buttons is why it is harder to operate.
> Thats my point, a 747 is hard to operate.
> How long does it take to do PPL?
Is it still 40 hrs min ? I'd heard somewhere you could do it in less now. 35 ?
FAA maybe or JAA.
> How long does it take to be instrument rated multi engine?
Well, you have to get some hours behind you first IIRC. Same for CPL etc.
From: Eeyore on 18 Jun 2008 15:48
> Eeyore wrote:
> > Brimstone wrote:
> >> Eeyore wrote:
> >>> Brimstone wrote:
> >>>> Hiram wrote:
> >>>>> "Brimstone" wrote:
> >>>>>>> The point I'm trying to make is - flying an aircraft is harder
> >>>>>>> than driving a truck. Much harder.
> >>>>>> How so, are there idiots in small runabouts, traffic lights,
> >>>>>> roundabouts and pedestrians with a death wish at 10,000 ft as
> >>>>>> well?-
> >>>>> OK, let me specify something here.
> >>>>> Flying an aircraft is 'intellectually' harder than driving a
> >>>>> truck.
> >>>>> Happy now?
> >>>> No.
> >>> How so ?
> >> If flying was more intellectualy challenging than driving a road
> >> vehicle then we wouldn't have computers controlling aircraft.
> > The tortured logic behind that concept has left me baffled.
> Glad to know that my efforts weren't wasted. :-)
> > Are you saying for example that truck drivers would be better drivers
> > if they had no cruise control ?
> Cruise control doesn't steer the vehicle. Auto-pilot does.
I'd say that was a fairly academic distinction. Both affect the vehicle's x,y
> > Do you not also realise that a heck of a lot of that cockpit
> > automation was put there to get rid of the flight engineer in one
> > respect and to reduce pilot workload with routine 'stuff' so as they
> > could concentrate better on flying the plane ?
> AIUI autopilot was devided so that the pilot/s don't have to make minor
> adjustments throughout the flight to keep the a/c on track and at the
> correct height.
That's the original and 'classic' meaning of the term. That is still what it
does although as part of a more integrated system it may now be simply called
A/F (autoflight) - and additionally ensuring constant (or demanded) speed is
done by the A/T (auto throttle) but moving the power levers manually will
over-ride it, as does moving the 'stick' to the A/F (within limits but let's not
get too complicated). And there's the F/D (flight director) too. That's the bit
that controls the track / course of the aircraft when so demanded e.g. by the
These are merely 'slaves' to the FMS though. Like the FADEC that controls the
engines (or is that a slave of the A/T ?). Sometimes the edges get blurred.
And then of course there's NAV (navigational) inputs to the FMS from the
Inertial Reference System and more lately GPS.
EFIS and EICAS provide an 'interface' to the pilots, supplying the 'glass
cockpit' data for example and warning messages.
TCAS provides an independent anti-collision aid.
GPWS or EGPWS provides warning of danger of potential ground collision.
> > Oh, and to keep fuel costs down.
> That's a more recent added bounis I would suggest.
Part of FMS (which is if you like the master automation that talks to and
controls and monitors all the other automation sub-systems), but it itself
controlled by the pilots' inputs.
> > All so you can fly to wherever for �25.
> Err, no. Autopolit has been around a lot longer than that, although I accept
> has been refined and added to over the years.
It's the full FMS that has made 2 cockpit crew working possible (and fuel
economy) with the attendant cost savings.
Oh and stunning flight safety.
From: Raymond Keattch on 18 Jun 2008 17:51
On 18/06/2008 20:02:32, Eeyore wrote:
> The pilots are there to 'tell' the computers what to do (i.e to actually
> fly the aircraft using the control interface like the control wheel /
> sidestick, throttles etc and lets the computers do the basic
> 'housekeeping' like ensuring all the temps and pressures are correct and
> keeping a specific course if so demanded) and take over if they break.
I watched this video, and came to the conclusion that Conor must be on
Rover 75 CDTi