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How high do you fly?

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How high do you fly?

Old 25th Feb 2016, 04:23
  #81 (permalink)  
 
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I took a mate in the sim who with the benefit of 500 hours constantly told me how easy my job is. He came very unstuck at FL410 M.86 just doing straight and level. A turn had me in hysterical laughter. He was very surprised at a demo of the difference between high speed stall and mach buffet, and how close they can be and how alike they feel.

But a Vulcan at m.84 and FL410, that earns large respect!


SND
As I'm a mere PPL holder and this is the private flying forum I feel free to ask such a basic question!

Could you elaborate on that a little bit? I assume the tricky part you're referring to is juggling banking and holding attitude?
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Old 25th Feb 2016, 18:57
  #82 (permalink)  
 
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"Could you elaborate on that a little bit? I assume the tricky part you're referring to is juggling banking and holding attitude?"

Especially with a super critical wing. Aerodynamically you're not in a good place, but the engines and fuel flows love it. The aircraft becomes extremely twitchy. A high speed stall may not be far way if you mis-handle the pitch attitude. As BEagle pointed out earlier the sums actually leave you with quite a small gap between cruise mach no. and the stall. Have the thing at the max weight for the altitude and the margin is at its' thinnest. There was in an incident report some years ago about a Challenger 605 crew who climbed too early on a transatlantic flight and nearly lost the aircraft because they were overweight for the flight level they wanted.

Because auto-pilots are digital they are far better at controlling the aircraft at altitude than pilots. It is really interesting to watch a crew descend from FL420 to land without use of the automatics. The handling pilot will be mentally calculating at a hell of a rate while concentrating on flying as smoothly as possible, the monitoring pilot will be doing everything else, including the same mental calculations which the crew share between themselves, and doing everything else is quite a lot.

As an exercise it is one that makes for a sweaty shirt, there was a Greek airliner that decompressed a few years ago, a steward on a portable oxygen bottle got into the cockpit and took one of the seats (both pilots were unconscious) the steward held a ppl, if he had yelled for help on the radio the outcome may have been different, it is believed he disconnected the auto-pilot and lost control of the aircraft; The expectation of how a swept wing jet will fly compared to the reality catches people out. Down low, in the circuit they are great, you need to concentrate on inertia and the outside picture. At altitude they are utterly different, challenging and require different handling, and after nearly thirty years I'm still learning.

SND
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Old 25th Feb 2016, 22:51
  #83 (permalink)  
 
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Could you elaborate on that a little bit? I assume the tricky part you're referring to is juggling banking and holding attitude?
When I was in the mob I knew a 'high level' Canberra pilot. He said the problem was not getting up there but getting down. Mmo and stall were very close.
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Old 25th Feb 2016, 23:45
  #84 (permalink)  
 
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Originally Posted by Sir Niall Dementia View Post
As an exercise it is one that makes for a sweaty shirt, there was a Greek airliner that decompressed a few years ago, a steward on a portable oxygen bottle got into the cockpit and took one of the seats (both pilots were unconscious) the steward held a ppl, if he had yelled for help on the radio the outcome may have been different, it is believed he disconnected the auto-pilot and lost control of the aircraft;
If you are talking about Helios (which I believe you are as I'm not aware of any other remotely similar occurrences) the cabin crew member was actually a CPL holder.
I believe he was former Greek special forces, which was how he had managed to endure the hypoxia much better than others, once pax oxygen ran out he went on to the O2 cylinders.

From what I remember the aircraft went out of control due to flameout of one engine as a result of fuel exhaustion, not because AP was disconnected. He was unable to recover (due to the handling characteristics at altitude, exacerbated by thrust asymmetry and lack of B737 knowledge), but the second engine flamed out due to fuel exhaustion before the aircraft eventually crashed.
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Old 26th Feb 2016, 06:58
  #85 (permalink)  
 
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Especially with a super critical wing. Aerodynamically you're not in a good place, but the engines and fuel flows love it. The aircraft becomes extremely twitchy. A high speed stall may not be far way if you mis-handle the pitch attitude. As BEagle pointed out earlier the sums actually leave you with quite a small gap between cruise mach no. and the stall. Have the thing at the max weight for the altitude and the margin is at its' thinnest. There was in an incident report some years ago about a Challenger 605 crew who climbed too early on a transatlantic flight and nearly lost the aircraft because they were overweight for the flight level they wanted.

Because auto-pilots are digital they are far better at controlling the aircraft at altitude than pilots. It is really interesting to watch a crew descend from FL420 to land without use of the automatics. The handling pilot will be mentally calculating at a hell of a rate while concentrating on flying as smoothly as possible, the monitoring pilot will be doing everything else, including the same mental calculations which the crew share between themselves, and doing everything else is quite a lot.

As an exercise it is one that makes for a sweaty shirt, there was a Greek airliner that decompressed a few years ago, a steward on a portable oxygen bottle got into the cockpit and took one of the seats (both pilots were unconscious) the steward held a ppl, if he had yelled for help on the radio the outcome may have been different, it is believed he disconnected the auto-pilot and lost control of the aircraft; The expectation of how a swept wing jet will fly compared to the reality catches people out. Down low, in the circuit they are great, you need to concentrate on inertia and the outside picture. At altitude they are utterly different, challenging and require different handling, and after nearly thirty years I'm still learning.

SND
Well, you've just killed every single 'mental reenactment' of me saving the day on a commercial airliner. I watched an air crash investigation episode vis-a-via the greek hypoxia tragedy. I've always wondered whether I (a humble PPL holder) could, with the help of ATC, manage to bring the thing down safely. I guess you've answered that, ha!

Not as simple as pulling the power, keeping the nose down, ensuring you stay in a speed range and adjusting your descent profile with gentle power changes? That's all my PPL has given me!
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Old 26th Feb 2016, 09:21
  #86 (permalink)  
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I've always wondered whether I (a humble PPL holder) could, with the help of ATC, manage to bring the thing down safely. I guess you've answered that, ha!
There is no way you would be asked by ATC to disconnect the autopilot and hand fly
The chances of both pilots becoming incapacitated and the autopilot also failing at the same time must be almost zero

Pace
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Old 26th Feb 2016, 09:53
  #87 (permalink)  
 
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Lllama Farmer;

I bow to that; while I was typing I was trying to find the report, but couldn't. Found it now, it makes chilling reading.

Turbopropulsion;

Your PPL has given you a skill set designed to fit the type of aircraft you fly. Move onto other classes and your skill set is expanded for those areas. I did my PPL on a Tiger Moth at the end of the 1970's, getting out of a Tiger into a Commanche required a different approach to flying to achieve much the same aim. I find my current GA fixed wing flying helpful with my helicopter work (and vice versa) due to the routes and areas flown. The jet is totally different in terms of the flying, the approach to the flying is actually much the same.

SND
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Old 26th Feb 2016, 18:42
  #88 (permalink)  
 
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Well, you've just killed every single 'mental reenactment' of me saving the day on a commercial airliner. I watched an air crash investigation episode vis-a-via the greek hypoxia tragedy. I've always wondered whether I (a humble PPL holder) could, with the help of ATC, manage to bring the thing down safely. I guess you've answered that, ha!
If you left the autopilot in you would probably be fine being talked to an autoland. You would at least have the advantage of being able to understand what they were talking about when they refer to speed/altitude/heading/flaps and numerous other items a non pilot would have no idea about.
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Old 26th Feb 2016, 19:03
  #89 (permalink)  
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Foxmoth

Unless he was flying one Citation 550 I flew when auto failure was very likely I am sure the autopilot was playing mental games with me and would decide to fail at the most awkward times,

It would go crazy and whether it decided to capture an altitude was hit and miss.

The times you were ready for it the Auto called George would do a perfect capture.

The time you were busy else where it was determined to stick you in it.

George had a nasty trick up his sleeve. He would make a perfect altitude capture and level off and then with a grin on his face wait for you to relax and do something else then he would start creeping up tiny bit by tiny bit so you wouldn't notice.

Try to pass George over to the FO side and the crazy thing went haywire.

Took it to maintenance and rigged up on the ground George behaved perfectly.
So much so I was sure they thought I was exaggerating and it was only when I stuck the engineer in the aircraft on a test flight that George displayed his true colours.

Funnily they never really fixed George after repeated visits to the doctor and you had to live with his funny ways and not trust him one bit There was suspicion that at some time the wiring had been fiddled with in the depths of the old Citation.

But all good for the soul

Pace

Last edited by Pace; 26th Feb 2016 at 20:16.
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Old 26th Feb 2016, 22:58
  #90 (permalink)  
 
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He did say "commercial airliner", not sure how many Citations are used for that! Apart from a few third world countries most modern airliners have pretty good autopilots!
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Old 27th Feb 2016, 06:52
  #91 (permalink)  
 
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Quote:
Well, you've just killed every single 'mental reenactment' of me saving the day on a commercial airliner. I watched an air crash investigation episode vis-a-via the greek hypoxia tragedy. I've always wondered whether I (a humble PPL holder) could, with the help of ATC, manage to bring the thing down safely. I guess you've answered that, ha!
If you left the autopilot in you would probably be fine being talked to an autoland. You would at least have the advantage of being able to understand what they were talking about when they refer to speed/altitude/heading/flaps and numerous other items a non pilot would have no idea about.
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I am Maverick once again then!

There is no way you would be asked by ATC to disconnect the autopilot and hand fly
Ok, I hadn't even thought of this. What if, for whatever reason, it wasn't working? Would I not have even the remotest of chance with just a PPL?
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Old 27th Feb 2016, 10:08
  #92 (permalink)  
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If you were unlucky enough to have a failed autopilot I think its very unlikely there would be a successful outcome with a basic PPL of hand flying a commercial airline from say FL380 to a successful landing.

it Is not just about the skills required which are very different to flying a single engine piston but also about not becoming overloaded and loosing control from the situation itself and complexity and differences in the aircraft.

If you had the autopilot and someone was guiding you through what buttons to push then the PPL would give you a basic understanding which a non Pilot would not have.

thats my opinion but would be interested in what the heavy iron pilots here think

Even with my bottom of the pile business jet i do not think there would be a successful outcome to a landing from FL380 hand flown by a basic PPL and that is even presuming the weather condition were good

The biggest problems would be speed control, altitude control and profile control which would lead to overload and loss of control and we haven't even got to landing

Pace

Last edited by Pace; 27th Feb 2016 at 10:54.
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Old 27th Feb 2016, 11:41
  #93 (permalink)  
 
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I think that the viability of one of us PPLs "saving the day" has been done to death over the years. The most memorable factors for me have been:

A serious Flight Simmer probably has more chance of getting it down than a PPL, and,

There is no way you would be asked by ATC to disconnect the autopilot and hand fly
How does a bog standard PPL tell the difference between a PTT switch and the A/P disconnect button on the yoke?
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Old 27th Feb 2016, 11:52
  #94 (permalink)  
 
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Pace said-

With an auto failure at FL 380 it wasn't that hard hand flying a PA28
Please tell me that you descended out of RVSM if you were there?

we had 45 degree wing drops and asked for an immediate climb to over FL300 as the PA28 was almost uncontrollable
I don't want you to think that I'm picking on you but are we not meant to increase the buffet margin rather than decrease it in such situations?
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Old 27th Feb 2016, 13:05
  #95 (permalink)  
 
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Originally Posted by Pace View Post
If you were unlucky enough to have a failed autopilot I think its very unlikely there would be a successful outcome with a basic PPL of hand flying a commercial airline from say FL380 to a successful landing.
Hardly heavy iron, but it's been done in a B200, fortunately with a successful outcome.

Many of you will be familiar with the story, but I've included a link to the ATC comms for those who haven't heard it yet.
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Old 27th Feb 2016, 13:12
  #96 (permalink)  
 
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How does a bog standard PPL tell the difference between a PTT switch and the A/P disconnect button on the yoke?
Ask the cabin crew! Certainly in our company they are encouraged to come into the flight deck and learn where the PTT is (there is one on the pedestal as well, using that there is no chance of inadvertant autopilot disconnect!), normally we also show them how to set 7000 on the transponder.

In a modern airliner the route will be in the computer right up to joining the ILS so mainly a case of reseting the altitude and speed then engaging approach mode, you could be unlucky and not have the arrival programmed in but I would say you could be talked through that easily enough!
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Old 27th Feb 2016, 17:28
  #97 (permalink)  
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Hardly heavy iron, but it's been done in a B200, fortunately with a successful outcome.
Silert

As far as I know all these can a passenger land a Heavy jet experiments if the crew become incapacitated have all revolved around simulator experiments and the autopilot
I would be very interested to see how a basic PPL or passenger got on if the simulator was set up with a failed autopilot at FL380 on a dark night above cloud and the PPL/passenger was told to get on with it from working out how to communicate with ATC to landing the jet at destination.

I don't know the real not media situation with the B200 but know that such a claim was made with a supposed Grandmother flying a twin when her husband died at the controls. It described her as a non pilot but reality is she had flown extensively with her husband right seat for decades and had on numerous occasions acted as an FO to him. She still did an amazing job with the shock of loosing her husband but maybe not quite as the media portrayed it.

With my experience with even CPL /IR who have no jet or heavy turbine time control would have been lost without further training. That doesn't mean I am right and it can't be done just I would be very surprised

Pace
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Old 27th Feb 2016, 17:54
  #98 (permalink)  
 
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Originally Posted by Pace View Post
I would be very interested to see how a basic PPL or passenger got on ... ... with a failed autopilot at FL380 on a dark night above cloud and the PPL/passenger was told to get on with it from working out how to communicate with ATC to landing the jet at destination.
I'd be interested to see how a newly hired P2F copilot got on with this scenario.
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Old 27th Feb 2016, 18:11
  #99 (permalink)  
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One of the biggest problems is brain overload where the person literally freezes at the controls! The more experienced the less likely that is to happen
That can happen with any pilot where the loading becomes too extreme and the mind and actions go blank
Someone with no or little flight experience is starting from a very low level and overloading is very likely very quickly

Pace
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Old 27th Feb 2016, 19:13
  #100 (permalink)  
 
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back when I first got my PPL, my friends got me a red letter day flight sim experience. There I went full of cockiness and bravado saying that I could fly anything now with my PPl behind me, within 5 mins that all changed when I flew the 737 into the ground 4 miles short of final with all systems working, what got me was not the speed control but the being overloaded with systems, which took my concentration away from keeping the aircraft on the glideslope, after that and a good kick up the bum by myself I sheep went back in and took myself back to the mental state that I used when I was under instruction and landed the aircraft perfectly with and without the autopilot, but god did I sweat during that. The experience shook me to my very core and made me realise that I was not a perfect pilot but it has made me a better pilot since.

Fats
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