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Old 10-19-2017, 08:45 PM
dstarfire dstarfire is offline
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Piloting airliner before flight computers and autopilots

I've been watching a bunch of videos about airliner curiosities, terminology, practices, and such lately. The number of issues* and factors** pilots have to consider is mind-boggling. For example, weight (both overall and, possibly, it's distribution throughout the frame) changes as you burn through fuel; the effect of engine thrust varies with altitude and temperature; lift varies with altitude, temperature, and flight angle; landing and takeoff distances vary based on a ton of factors; you get the idea.

So, how did pilots manage before flight computers and autopilots? Did they just fly with much wider margins?


* i.e. tasks to perform/contingincies to plan for
** i.e. stuff to think about when considering the aforementioned issues
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  #2  
Old 10-19-2017, 09:31 PM
DSYoungEsq DSYoungEsq is offline
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Calling LSLGuy!
  #3  
Old 10-19-2017, 11:03 PM
Derleth Derleth is offline
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Well, there used to be more people up there.

The flight engineer and the navigator were, at one time, special roles in commercial flights, taking care of complex mechanical systems and navigation, respectively, before computers took over those jobs.

Flight engineer
Quote:
Starting in the 1980s, the development of powerful and small integrated circuits and other advances in computers and digital technology eliminated the need for flight engineers on airliners and many modern military aircraft. Some of the last aircraft built with FE stations were early-production Boeing 767s, Tupolev Tu-154s, and military variants of the Boeing 707, such as the E-3 Sentry and E-6 Mercury.

On two-pilot flight deck airplanes, sensors and computers monitor and adjust systems automatically.[3] There is no onboard technical expert and third pair of eyes. If a malfunction, abnormality or emergency occurs, it is displayed on an electronic display panel and the computer automatically initiates corrective action to rectify the abnormal condition. One pilot does the flying and the other pilot resolves the issue. Modern technological advancements in today's aircraft have reduced the dependence upon human control over systems.[3]
Air navigation:
Quote:
Civilian flight navigators (a mostly redundant aircrew position, also called 'air navigator' or 'flight navigator'), were employed on older aircraft, typically between the late-1910s and the 1970s. The crew member, occasionally two navigation crew members for some flights, was responsible for the trip navigation, including its dead reckoning and celestial navigation. This was especially essential when trips were flown over oceans or other large bodies of water, where radio navigation aids were not originally available. (GPS coverage is now provided worldwide). As sophisticated electronic and space-based GPS systems came online, the navigator's position was discontinued and its function was assumed by dual-licensed pilot-navigators, and still later by the flight's primary pilots (Captain and First Officer), resulting in a downsizing in the number of aircrew positions for commercial flights. As the installation of electronic navigation systems into the Captain's and FO's instrument panels was relatively straight forward, the navigator's position in commercial aviation (but not necessarily military aviation) became redundant. (Some countries task their air forces to fly without navigation aids during wartime, thus still requiring a navigator's position). Most civilian air navigators were retired or made redundant by the early 1980s.[2]
I'm reminded of an old joke: One day, the entire aircrew is going to be reduced to a pilot and a dog; the pilot will fly the plane, and the dog will bite the pilot if he so much as thinks of actually touching any of the controls.
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Old 10-19-2017, 11:10 PM
PastTense PastTense is offline
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Autopilots are actually a fairly old technology:
Quote:
In the early days of aviation, aircraft required the continuous attention of a pilot in order to fly safely. As aircraft range increased allowing flights of many hours, the constant attention led to serious fatigue. An autopilot is designed to perform some of the tasks of the pilot.
The first aircraft autopilot was developed by Sperry Corporation in 1912. The autopilot connected a gyroscopic heading indicator and attitude indicator to hydraulically operated elevators and rudder. (Ailerons were not connected as wing dihedral was counted upon to produce the necessary roll stability.) It permitted the aircraft to fly straight and level on a compass course without a pilot's attention, greatly reducing the pilot's workload.
Lawrence Sperry (the son of famous inventor Elmer Sperry) demonstrated it in 1914 at an aviation safety contest held in Paris. At the contest, Sperry demonstrated the credibility of the invention by flying the aircraft with his hands away from the controls and visible to onlookers of the contest. Elmer Sperry Jr., the son of Lawrence Sperry, and Capt Shiras continued work after the war on the same autopilot, and in 1930 they tested a more compact and reliable autopilot which kept a US Army Air Corps aircraft on a true heading and altitude for three hours.
In 1930, the Royal Aircraft Establishment in the United Kingdom developed an autopilot called a pilots' assister that used a pneumatically-spun gyroscope to move the flight controls.
Further development of the autopilot was performed, such as improved control algorithms and hydraulic servomechanisms. Also, inclusion of additional instrumentation such as the radio-navigation aids made it possible to fly during night and in bad weather. In 1947 a US Air Force C-54 made a transatlantic flight, including takeoff and landing, completely under the control of an autopilot. Bill Lear developed his F-5 automatic pilot and automatic approach control system, and was awarded the Collier Trophy for 1949.
In the early 1920s, the Standard Oil tanker J.A. Moffet became the first ship to use an autopilot.
https://en.wikipedia.org/wiki/Autopilot

Last edited by PastTense; 10-19-2017 at 11:11 PM.
  #5  
Old 10-20-2017, 12:09 AM
Broomstick Broomstick is offline
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Originally Posted by dstarfire View Post
So, how did pilots manage before flight computers and autopilots?
Behold he E6B flight computer, a.k.a. "whiz wheel", a circular slide rule used by pilots from the 1940's onward for flight calculations both during pre-flight planning and, when needed, while enroute.
  #6  
Old 10-20-2017, 12:20 AM
Richard Pearse Richard Pearse is online now
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Originally Posted by dstarfire View Post
I've been watching a bunch of videos about airliner curiosities, terminology, practices, and such lately. The number of issues* and factors** pilots have to consider is mind-boggling. For example, weight (both overall and, possibly, it's distribution throughout the frame) changes as you burn through fuel; the effect of engine thrust varies with altitude and temperature; lift varies with altitude, temperature, and flight angle; landing and takeoff distances vary based on a ton of factors; you get the idea.

So, how did pilots manage before flight computers and autopilots? Did they just fly with much wider margins?


* i.e. tasks to perform/contingincies to plan for
** i.e. stuff to think about when considering the aforementioned issues
I feel like I should be a good person to answer this stuff because the fleet I fly ranges from aircraft with autopilots that basically don't work (BAe146), to aircraft with quite modern autopilots and systems (Avro RJ). We also use a range of old fashioned support systems on the ground and some more modern computer assisted systems. I'm not sure where to start though so I'll tackle the examples in your post and see where it leads.

The specific issues you've listed aren't as big a deal as you might think and the use of autopilot and flight management computers* don't make a huge difference. A lot of data that is used by flight management computers was just presented as tables in books in the olden days (and still is for pilots like me who fly old tech). The autopilot is just another pilot really. It's there to reduce your workload but it's not doing anything that the meat pilots couldn't easily be doing.

1. Weight pt 1. Pre-flight, this is taken care of by load controllers and flight planning people. Load control tells flight planing what the expected payload is, flight planing plans the flight and tells load control what the fuel uplift and burn will be, and load control add the fuel figures to their data and produce a load and trim sheet that has passengers and cargo correctly positioned so that no weight limits are exceeded for the flight. Load control and flight planning may be using computers or paper or a combination.

The load/trim sheet can be automated to some extent or may be manual. I work for a contract company and on some contracts the pilots are still doing manual trim sheets, it takes a few minutes.

A manual load / trim sheet has a graph depicting the aircraft centre of gravity limits and you manually plot the position of the CofG for various stages of the flight and make sure the plot is inside the box.

2. Weight pt 2. With the aircraft correctly loaded on the ground there is not much for the pilot to do in flight other than fly. Large aircraft with complicated fuel systems may need to have fuel moved around to keep weight within limits, but this is generally taken care of with simple one-size-fits-all procedures such as burning fuel from tanks in a particular order. LSLGuy can provide more detail on this as my 100 seat RJ is very simple and we don't have to think about weight distribution in flight at all.

As far as handling goes, it's a bit like driving your car with different loads and different amounts of fuel. The handling will be different with four adults and full fuel compared to just a driver and a nearly empty tank, but you don't really concern yourself too much with it. You unconsciously adjust your driving to account for it. Flying is the same. The handling will change throughout the flight but you just do what you need to do to get the result you want.

3. Changing engine and aerodynamic performance. A bit like changes in handling, you don't really think about it, you just do what you need to do to get the desired result. At high altitude you need close to max thrust to maintain cruise speed, at low altitude you need far less. You don't need to give it whole lot of thought though, you just set whatever thrust you need to get the speed you want while taking care not to put any engine indications out of limits. When you drive your car uphill you know that you will need more power to maintain speed but you don't analyse it too much you simply adjust the accelerator pedal to get the speed you want. If your foot touches the floor then you change down a gear while being careful not to put the engine rpm into the red arc.

There are certain limits on flight and the flight management computer (FMC) and other modern systems can be helpful in displaying what those limits are but there are other methods to achieve the same thing. While an FMC can tell you if an altitude is achievable, a simple tabulated chart of weight vs temperature can do the same for a non FMC aircraft. A modern speed tape will have dynamic low speed and high speed limits shown while in an older aircraft you may just need to know not to fly slower than a certain indicated speed while above a certain height.

When flying the BAe146, which doesn't have much in the way of technology, we have a card in the flight deck displaying our current weight to the nearest 1000 kg. On the card are a list of important speeds such as take off and approach speeds for various flap settings. One of those speeds is "Ver", the minimum clean speed (i.e., flaps up). When we are above 27,000' we just need to know not to fly slower than Ver plus 20 knots.

4. Landing and take-off data. Landing data is simple enough and is presented as tables in a book or the electronic equivalent. Take-off data is more involved. For a long time this has been taken care of by performance specialists. You are right that it is complicated and pilots are not generally trained to be able to do it. This is not a case of technology vs no technology, it's more that it is a very involved process that must be carried out for every runway that you could possibly be operating from and must account for every likely combination of weight, temperature, wind, and atmospheric pressure. It's not something you can just do in a few minutes the way a load and trim sheet is. From a pilot's perspective you are either presented with tables in a book or an electronic version of the same thing. The result is the same for us, find the ambient conditions and look them up in the relevant table or enter them into the EFB. From there you'll be given a max take-off weight or you may wish to work out a minimum thrust setting to use, they are both closely related.

The presence of technology in the cockpit doesn't make a big difference with take-off data. An EFB setup can streamline the process and reduce errors though it does have its own disadvantages.

So, to sum up, flight management computers and autopilots are useful bits of kit but they are not game changes for the specific problems you mention. On the other hand, FMCs and the way they work as a navigation computer have made a huge difference to navigation. Without good nav systems and associated flight management computers, the pilot's job would be much more involved (except it wouldn't, because that work would be done by the navigator or flight engineer).


* I assume you mean flight management computers and not fly-by-wire which is far from universal.

Quote:
Originally Posted by Broomstick
Behold he E6B flight computer, a.k.a. "whiz wheel", a circular slide rule used by pilots from the 1940's onward for flight calculations both during pre-flight planning and, when needed, while enroute.
I still carry one actually. A more compact version produced by Jeppesen. Never used it in anger but something makes me very reluctant to remove it from the bag.
  #7  
Old 10-20-2017, 10:23 AM
JHBoom JHBoom is offline
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Before autopilot systems were widely installed, pilots "hand flew" the airplane through all phases of flight. Ernest K. Gann's Fate Is The Hunter does an excellent job (IMO) of illustrating what commercial & airline piloting was like in the early days, and has a passage that speaks specifically about hand-flying an aircraft (DC-3, IIRC) to exacting altitude & airspeed standards in spite of distraction, both natural and manmade.

----------------------

Fun aviation trivia:
Lawrence Sperry, the aforementioned inventor of the autopilot, is also generally acknowledged as the founding member of the "Mile High Club". Makes you wonder which one ol' Larry thought of first - the autopilot, or the in-flight nookie......
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Old 10-20-2017, 10:25 AM
running coach running coach is online now
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Quote:
Originally Posted by JHBoom View Post
Before autopilot systems were widely installed, pilots "hand flew" the airplane through all phases of flight. Ernest K. Gann's Fate Is The Hunter does an excellent job (IMO) of illustrating what commercial & airline piloting was like in the early days, and has a passage that speaks specifically about hand-flying an aircraft (DC-3, IIRC) to exacting altitude & airspeed standards in spite of distraction, both natural and manmade.

----------------------

Fun aviation trivia:
Lawrence Sperry, the aforementioned inventor of the autopilot, is also generally acknowledged as the founding member of the "Mile High Club". Makes you wonder which one ol' Larry thought of first - the autopilot, or the in-flight nookie......
Obviously the autopilot. You want something to keep it up when you're getting it up.
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Old 10-20-2017, 11:09 AM
kunilou kunilou is offline
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As early as 1924 markers were set out to guide air mail pilots. They included beacons for nighttime and giant arrows on the ground for daytime.
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Old 10-20-2017, 11:48 AM
LSLGuy LSLGuy is offline
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Quote:
Originally Posted by dstarfire View Post
I've been watching a bunch of videos about airliner curiosities, terminology, practices, and such lately. The number of issues* and factors** pilots have to consider is mind-boggling. For example, weight (both overall and, possibly, it's distribution throughout the frame) changes as you burn through fuel; the effect of engine thrust varies with altitude and temperature; lift varies with altitude, temperature, and flight angle; landing and takeoff distances vary based on a ton of factors; you get the idea.

So, how did pilots manage before flight computers and autopilots? Did they just fly with much wider margins?...
As Richard said so well ...

The administrivia gets detailed. But all that is done while the airplane is parked. In the Olden Dayes somebody sat down with what looked like a tax form and a pencil and totted everything up then looked up some limits in a big book of tables to derive the answers. Nowadays there's a computer program at HQ that does all the totaling and table looking up. Which we get as a printout, or in the latest iteration, a download to our iPad or datalinked directly into the airplane. We still have the forms and procedures to do the whole shebang manually if there's a big computer outage.

The tolerances haven't changed a bit. Just how much human sweat goes into adding and subtracting.


As to flying, it's (unsurprisingly) as Richard said. You do whatever it takes to make the jet go where you want it to. And we still use a combo of new and old methods when it comes to verifying navigational or limitational stuff.

E.g. about half-way up every one of our climbs after takeoff, we check the computer to ensure it thinks we are light enough to climb to the planned cruising altitude. As a separate matter we consult our ground paperwork to determine our zero fuel weight, add the weight of fuel shown at the moment, and consult a sheet of cardstock stored in the cockpit which lists the maximum allowable weight for various combinations of altitude, speed, and degree of turbulence. Both should agree that we're capable of making the planned cruise altitude by X margin of weight. Knowing X's value is actually the most useful outcome: that "slack weight" is a real good proxy for how much excess performance will be available and how quickly, or not, any encounter with turbulence or mountain wave would become critical.

Both the computer and the people recheck this stuff periodically as the fuel weight burns off. It's frequently advantageous to climb as the flight wears on. But you want to retain a reasonable X margin.

etc., for another 20 factors. The computer continuously figures out lots of nice-to-know info. But very little of that is trully need to know all the time. We can estimate or compute the need to know stuff real quickly.

There may come a time when pilots have lost how to do this themselves and if HAL doesn't know then nobody will know. IMO that won't be progress.
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Old 10-20-2017, 12:18 PM
GreenWyvern GreenWyvern is offline
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Originally Posted by dstarfire View Post
So, how did pilots manage before flight computers and autopilots? Did they just fly with much wider margins?
The seat of their pants was as wide as necessary.
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Old 10-20-2017, 01:35 PM
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Originally Posted by running coach View Post
Obviously the autopilot. You want something to keep it up when you're getting it up.
And you've wasted your time if you drift below a mile high, you'd have to do it all over again.


* * * *
There's the story I read when China was first modernizing and thinking of replacing their Russian airliners with some Boeing back in the 80's. The engineers from Boeing were trying to understand how the airline currently calculated takeoff capability at, for example, Lhasa where the airport is about 11,000 ft high. After some back-and-forth they finally realized what the airline pilots were saying was: "we start the runway roll, and if we pass that marker there and are still not airborne, we jam on the brakes and go back and unload some passengers and luggage and try again."
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Old 10-20-2017, 02:30 PM
Senegoid Senegoid is offline
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As far as handling goes, it's a bit like driving your car with different loads and different amounts of fuel. The handling will be different with four adults and full fuel compared to just a driver and a nearly empty tank, but you don't really concern yourself too much with it. You unconsciously adjust your driving to account for it. Flying is the same. The handling will change throughout the flight but you just do what you need to do to get the result you want.
In other words, "Just fly the plane!"

Works for me, sort of, and hopefully will work a lot better as I get better at it. Whenever I ask my instructors for more details instruction on various techniques (like, how to steer down a runway in a crosswind), one of my instructors typically says "Just fly the plane!"

I've got a pilot friend that I go flying with now and then (in small GA airplanes or gliders). We recently talked about the prospect of having self-flying airplanes, in the same sense as the current notions of a self-driving car. There was just recently something in the news about Microsoft working on such a thing. (ETA: Added linky.)

One of the points was, that some people fly little GA planes because, y'know, it's fun to do (the proverbial "$100 hamburger" being just a pretext to go flying). What will it be like when there's a whole generation of "pilots" who only know how to push the "Start" button but have never flown stick and rudder? Where's the fun in that?
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Old 10-20-2017, 02:48 PM
Senegoid Senegoid is offline
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All those millions of things the pilot has to be thinking about:

One instructor told me this little story once: (And note, this is just about flying a little GA plane, let alone an airliner):

One of his students made a list of everything a pilot needs to be thinking about while landing an airplane. (And note, this is just about flying a little GA plane at a GA airport, let alone an airliner.) He came up with a list of something like 130-some things the pilot has to keep in mind.

There's an apparently well-known phenomenon among student pilots and their instructors: Vastly many beginning student pilots are phobic about learning to use the radio. It seems that there's so much for the newbie pilot to think about, it fully occupies all their mental bandwidth, and talking on the radio (with its somewhat contrived and scripted artificial language) alone takes up a shitload of mental bandwidth (for a newbie). Taken all together, it's just too much mental overload for a beginning pilot to fly the plane during the pattern and landing, and talk on the radio at the same time.
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Old 10-20-2017, 03:20 PM
dstarfire dstarfire is offline
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Thank you all for the information. It sounds like flying is/was a lot less precise without flight computers. I was thinking each control has to be set to a specific value based on conditions. But y'all are saying you calculate an estimated value then adjust it as needed to get the result you want. Also, a lot of the stuff is just efficiency-maximizing gravy.

BY "control" I'm referring to: throttle, offsets for the manual controls (so a neutral flight yoke position = level), weight adjustment unit*, and the like (I'm wanting to think some of the wing surfaces like flaps and slats are used beyond takeoff and landing but I know that's not true). One example (I just thought of), how do you handle the situation on a dual engine plane if one engine is performing slightly better or worse? Do you manually adjust individual engine throttle (I'd think that would get tricky when you go to adjust overall throttle)?



*I made that one up.
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Old 10-20-2017, 06:03 PM
LSLGuy LSLGuy is offline
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I was hoping you'd come back to explain what you meant. Now we can give you something closer to what you meant.

In your car when you drive do you hold the wheel exactly straight? Or do you gently zig and zag slightly turning the steering wheel as necessary to keep the car in the lane? How do you maintain speed? By selecting a foot position or by looking at the speedo and gently adjusting foot position to hold, say, 60mph regardless of changing wind or slope or surface?

We do exactly the same thing. There's a few things that are carefully pre-calculated and pre-set. But after that everything is adjusted as needed to maintain the target. Whether that target is a speed, an altitude, a course, or a point of impact with a runway.


Your example of two slightly different engines is well-chosen. That happens every day. Have you ever driven a car that pulls to the left or right? Pain in the ass, but you cope. You hold in a little left steering to keep your car going straight despite the car's desire to turn right. You're stuck; there's nothing you can adjust while driving to correct that pulling tendency; you just need to fight it until you can get it fixed at the shop.

In airplanes there are 4 axes of control: roll (bank left/right), pitch (nose up/down), and yaw (swivel left/right). Plus total engine output power.

In small airplanes there is an adjustment, called "trim", to fine tune control in the pitch axis so the airplane nose will neither move up nor down at the current combination of power, weight, speed, and altitude. Works good. For the other two axes, any imbalance in the airplane and the forces acting on it is just there. The airplane wants to pull left or right and your job is to sit there and hold the controls a little opposite as needed to keep everything going where you want.

In bigger airplanes there is "trim" on all three directional axes. And we're continually tweaking one or another so the thing flies true. You start out by pushing the two throttles forward together. When you get close to the correct power setting (think like RPM in your car) you diddle each throttle individually until they both/all read the correct number. Then away you go. Almost inevitably one will still be putting out more power than the other. So you offset that with a smidgen of rudder input while things are dynamic and once you've settled down to a more steady state, adjust out the asymmetry with some combo of moving the throttles differentially, and adjusting the various trims.

And yes, everything you adjust affects everything else. A tweak of power triggers a need for rudder & pitch trim, and maybe even roll trim. Over time as the machinery gets cold at altitude and weight burns off it all needs adjusting again. And again. And again.

Each and every airplane is slightly out of perfect adjustment of all the moving parts. They're even slightly bent here and there. Just like all cars' wheels are slightly misaligned. The older they get, the crookeder they fly. So we tweak the adjustments to fly as straight as possible and write up maintenance discrepanacies if one is excessively crooked.

Last edited by LSLGuy; 10-20-2017 at 06:06 PM.
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Old 10-20-2017, 06:10 PM
Xema Xema is offline
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Originally Posted by Senegoid View Post
In other words, "Just fly the plane!"
Aka: "Stick and rudder as necessary"
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Old 10-20-2017, 06:32 PM
Richard Pearse Richard Pearse is online now
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Originally Posted by dstarfire View Post
Thank you all for the information. It sounds like flying is/was a lot less precise without flight computers. I was thinking each control has to be set to a specific value based on conditions. But y'all are saying you calculate an estimated value then adjust it as needed to get the result you want. Also, a lot of the stuff is just efficiency-maximizing gravy.
Still not sure what you mean by "flight computers". Airliners have a flight management computer which is basically a navigator. It has the flight route loaded into it and using a number of different navigation sensors (radio beacons, GPS, IRS etc) it calculates where the aircraft is and sends inputs to the autopilot to tell the autopilot how to steer to keep on the nominated track. It also has performance data and fuel inputs that allow it to calculate things such as how much fuel you'll have at the destination, and how high / fast you should fly to balance fuel savings against staying on schedule.

There are a raft of other small computers on board that look after various things such as thrust settings and pressurisation.

Some airliners have a fly by wire system that consists of a computer between the pilot's flight controls and the control surfaces. It gives the illusion that the pilot is directly flying the aircraft but if the pilot tried to bank or pitch too much the FBW wouldn't allow it. This is still relatively rare on Boeings, I think the B777 and B787 have it, but earlier types don't. Airbus from the A320 onwards have FBW. Is this what you mean by flight computers?

Quote:
BY "control" I'm referring to: throttle, offsets for the manual controls (so a neutral flight yoke position = level), weight adjustment unit*, and the like (I'm wanting to think some of the wing surfaces like flaps and slats are used beyond takeoff and landing but I know that's not true). One example (I just thought of), how do you handle the situation on a dual engine plane if one engine is performing slightly better or worse? Do you manually adjust individual engine throttle (I'd think that would get tricky when you go to adjust overall throttle)?
A small amount of imbalance between engines doesn't do much other than create an annoying dissonance in the combined engine sound. You get a "beat" similar to playing two slightly out of tune guitar strings.

That said, normally a thrust computer of some sort sits between the throttles and the engines and can smooth out variations in engine performance so that with thrust levers lined up, the engine thrust is the same on each engine. If this is turned off and the engines are mismatched you may get some thrust lever stagger if you manually match the engines.

While cruising you don't normally have much reason to adjust the thrust so if you do have thrust computers off or not fitted, you may adjust the thrust levers with some stagger to try match the engines. Once you are flying the approach though, it is easiest to just move them together--the affect on handling is not noticeable.
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Old 10-20-2017, 06:42 PM
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Originally Posted by kunilou View Post
As early as 1924 markers were set out to guide air mail pilots. They included beacons for nighttime and giant arrows on the ground for daytime.
That is so cool.
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Old 10-20-2017, 06:45 PM
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It seems to me from the above, that the biggest problem for early aviators was navigation; especially in the dark. With no satellites flying a compass bearing was pretty inaccurate. If there was a navigator (as in military planes) then they could use the stars to navigate by. I watched a film about an air strike during WW2 where the bombers flew from Australia to Japan and back; much of the 15-hour flight in darkness and bad weather. Record-breaking in its day.

I have also read about the brave people, many female, who ferried plane of all types of planes from Spitfires to Lancaster bombers from the factories to the bases where they were to be used. They flew alone, with no weapons to defend themselves and they were flying at night over a blacked out country.
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Old 10-20-2017, 09:14 PM
dstarfire dstarfire is offline
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Yes, trim is the thing I was thinking was on the wings (I learned about from one flight lesson in a little Cessna many years ago).

"Flight computer" provides information (some from sensors, some calculated based on sensor or entered information) but doesn't control the aircraft (at best, it can provides suggestions to the pilot). On the airbus A320 (in Captain Joe videos) I'm thinking it's a panel on the center console, near the pilots knee. It has a numeric keypad, the letters A-F, some other keys, and a small display with some hotkeys around the edge.

I said "flight computers and autopilots" because I'd assumed flight computers were in use or available before electronic autopilots. ... I am aware there was a gyroscope-based autopilot that was invented just a few years after the Wright brothers' flight.
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  #22  
Old 10-20-2017, 09:48 PM
LSLGuy LSLGuy is offline
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The thing you're calling a "flight computer" is properly a "flight management system" = FMS.

It's mostly a navigator. It has a database of the locations of all the relevant nav points and when coupled to a source for aircraft position and speed can figure out which way to go to get someplace and how long it'll take to get there.

Its other major function is performance computations. It knows about weight limits, fuel consumption depending on altitude and other variables, etc. So if it knows how much fuel you start with, it can compute how much you'll end with according to the current plan. If you change the plan it'll promptly recalculate the expectations all the way to landing.

It's a big labor saver when significant changes are needed enroute. But for the typical case of HQ creating a plan for us to get from ABC to DEF that is then flown pretty much as planned, there's very little info coming from the FMS that we don't already have on our old-fashioned paperwork.

It does provide labor saving in that we can keystroke in the route before we leave the gate. Then HAL (as we often call it) will guide the plane from nav fix to nav fix without us having to fiddle with radio beacons and such. In essence it becomes the "master brain" doing the strategic control while leaving the detailed "pull back to go up" flying to the autopilot and its muscles. Then our job becomes watching the watcher, changing the plan as necessary, and intervening when HAL starts doing something stupid.

For the cruise portion of the flight, HAL reduces error. For the more dynamic departure and especially arrival environment, there comes a point where it's usually better to simply cut HAL off and operate without his "help". Keeping him synced up with a rapidly evolving tactical plan negotiated between us and ATC all the while we're closing rapidly towards the ground eventually becomes more trouble and distraction that it's worth.

Knowing when and how to switch between fully automated versus fully manual control and the several intermediate mixed levels is an evolving science and art. People have died by driving the computer when they should have been driving the jet. And vice versa.

Last edited by LSLGuy; 10-20-2017 at 09:49 PM.
  #23  
Old 10-20-2017, 09:57 PM
zombywoof zombywoof is offline
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Originally Posted by Senegoid View Post
talking on the radio (with its somewhat contrived and scripted artificial language) alone takes up a shitload of mental bandwidth
IANAP, but had a coworker who used to like to tell stories about his days as a pilot in the US Marines - I remember him saying they were taught that when in trouble, their priorities in descending order of importance were "1. Aviate, 2. Navigate, 3. Communicate."
  #24  
Old 10-20-2017, 10:07 PM
Richard Pearse Richard Pearse is online now
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Ah yeah, so that's a flight management computer, also known as a flight management system. At its heart it is a navigation computer. Life without it would mean only flying airways that are served by radio beacons and having to tune frequencies and dial up courses by hand. There would be some periods in flight where you'd be out of range of the radio beacons and would have to use dead reckoning (set heading based on estimated winds) until you came within range of the next beacon. It's not rocket science but is not nearly as accurate as FMC computed position based on all available sensors. The lack of the FMC would also mean more manual calculation of things such as fuel remaining, current weight, landing weight, etc. Most pilots still calculate these things manually, or at least estimate them, as a cross check of what the FMC is saying anyway.

I have flown some BAe146s that had a GPS nav unit but it wasn't really a flight management computer and it couldn't be coupled to the autopilot, meaning the pilot had to operate the autopilot in heading mode, manually adjusting heading to stay on the track calculated by the GPS.

On preview I see I've been Ninja'd!

Quote:
Originally Posted by zombywoof
"1. Aviate, 2. Navigate, 3. Communicate."
Yes, a very good set of basic priorities.
  #25  
Old 10-21-2017, 01:44 AM
md2000 md2000 is online now
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With the small airplanes, and so I imagine with the really big ones - much of the grunt work is done on the ground. They have a pretty good idea of the distribution of and weight of passengers and luggage, fuel etc. that's not something you wok on after the doors are closed before takeoff. Similarly, you have a pretty good idea of the path, winds aloft strength and angles, and so roughly what headings you have to fly. These adjust as necessary. You have to try really hard or be pretty negligent to overload or load out of CG a large airliner. They are designed and procedures are set to not do so. Also, while flying you use feedback from the route to update the flight plan (which on a large airliner, included a navigator). So indicated air speed plus distance covered between points told you wind speed. This allowed you to calculate how fuel was doing, but airlines by law have to have a pretty good reserve, and you keep an eye on fuel levels, so you'll know well before it's too late 9we hope) if fuel is a problem. Another part of the predetermined plan is where to divert at any point if there's an emergency.

So the only thing to do is fly, and worry about flight plan once airborne. Air traffic control will get you most of the way to flying altitude (and today, most of the trip). As others mention, just run the controls to match the flight plan - this airspeed, this heading,this altitude - until we reach this waypoint; etc. And as also mentioned, flying, like driving while staying between the dotted lines, was mostly a matter of paying attention to the instruments and/or looking out the window and adjusting accordingly. IIRC there was a trim and some small aircraft (am I remembering this right?) had a similar rudder tab adjustment. Set those properly and you could take your hands off for several minutes and the aircraft would maintain direction and altitude. I recall some instructors using only the trim wheel to maintain altitude... if we appear to be descending slightly, adjust us up a little more...

Last edited by md2000; 10-21-2017 at 01:45 AM.
  #26  
Old 10-21-2017, 03:37 AM
Senegoid Senegoid is offline
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Originally Posted by zombywoof View Post
. . . priorities in descending order of importance were "1. Aviate, 2. Navigate, 3. Communicate."
Yes, I guess that's an entrenched standard aviation wisdom. In my little glider club, the instructors are always beating that us into our heads too.

If you get the plane trimmed right, it can pretty much fly itself. I've posted a video of me flying a glider in quite a few threads by now where there was some relevant point to be made ... (here it is yet again) Early in the flight, the pilot in the back seat (heard but not seen in this video) remarks, twice, that the glider can fly itself better than the pilot can. He demonstrates that the glider will fly itself in "Look, Ma, no hands" mode. Shortly afterward he has me try it, during a fairly steeply banked turn. By pulling the trim back, the nose of the glider stays up, and it also remains in a stable steep turn, hands off!
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Old 10-21-2017, 03:45 AM
Robot Arm Robot Arm is offline
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And as also mentioned, flying, like driving while staying between the dotted lines, was mostly a matter of paying attention to the instruments and/or looking out the window and adjusting accordingly. IIRC there was a trim and some small aircraft (am I remembering this right?) had a similar rudder tab adjustment. Set those properly and you could take your hands off for several minutes and the aircraft would maintain direction and altitude. I recall some instructors using only the trim wheel to maintain altitude... if we appear to be descending slightly, adjust us up a little more...
I was flying with my dad once in a Cessna and he showed me something really interesting. We had the plane trimmed and balanced, were flying straight and level, 80mph, hands and feet off the controls. He told me to push the throttle forward a bit. I did. The plane did not speed up, it started climbing. I pulled the throttle out and we leveled off. Pulled it out some more and we started descending; all hands-off and 80mph. I don't know if it's true in all planes and all conditions, but there's a way of thinking that says that the yoke (or stick) and elevator trim control the plane's speed, and the engine controls make it climb or dive.

Interesting that there's another BAe 146 pilot here. My dad had some time in those (or it may have been the Avro RJ by then).
  #28  
Old 10-21-2017, 04:11 AM
thirdname thirdname is offline
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With the small airplanes, and so I imagine with the really big ones - much of the grunt work is done on the ground.
Yes, here's a video where a pilot shows a large folder of information he receives before a flight. It has things like takeoff speeds, the planned route with altitudes and airspeeds, what airports to divert to in an emergency, weather info, and more.

Cockpit Chronicles: Paper makes a plane fly
  #29  
Old 10-21-2017, 06:19 AM
Richard Pearse Richard Pearse is online now
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Originally Posted by thirdname View Post
Yes, here's a video where a pilot shows a large folder of information he receives before a flight. It has things like takeoff speeds, the planned route with altitudes and airspeeds, what airports to divert to in an emergency, weather info, and more.

Cockpit Chronicles: Paper makes a plane fly
Interesting.

Flying short haul for a small company that doesn't have a flight planning department, we have access to the same information but we print it ourselves and tend to filter it prior to printing. We will look at the weather maps and if there's nothing interesting we just won't print it. Our flight plan, fuel plan, flight log and anything else to do with navigating is on two, sometimes three, pieces of paper.

Other stuff they had as part of their package, such as the take-off data for the airport, we just have in a book that stays in the aeroplane. It's not specific to a flight but covers the likely range of scenarios that we would encounter through the year.

Navigation charts are our own personal items with most of us using an iPad app rather than paper.
  #30  
Old 10-21-2017, 06:30 AM
Richard Pearse Richard Pearse is online now
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Originally Posted by Robot Arm View Post
I was flying with my dad once in a Cessna and he showed me something really interesting. We had the plane trimmed and balanced, were flying straight and level, 80mph, hands and feet off the controls. He told me to push the throttle forward a bit. I did. The plane did not speed up, it started climbing. I pulled the throttle out and we leveled off. Pulled it out some more and we started descending; all hands-off and 80mph. I don't know if it's true in all planes and all conditions, but there's a way of thinking that says that the yoke (or stick) and elevator trim control the plane's speed, and the engine controls make it climb or dive.
Yes you basically trim for a speed. If you add power you go faster which creates more lift over the wings and you climb, if you reduce power the opposite happens. One way of descending using the autopilot is to set a lower altitude in the altitude window then select "level change". The auto throttle retards the thrust levers towards idle and the autopilot attempts to maintain the selected speed in the only way it can, by pitching down. This is not quite the same as what was demonstrated to you, but very similar.

Quote:
Interesting that there's another BAe 146 pilot here. My dad had some time in those (or it may have been the Avro RJ by then).
Do you know if he liked it? I've been flying it for the last 6 years and I don't know if I like it or not. A bit of a love / hate relationship.
  #31  
Old 10-21-2017, 10:27 AM
md2000 md2000 is online now
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Yes, here's a video where a pilot shows a large folder of information he receives before a flight. It has things like takeoff speeds, the planned route with altitudes and airspeeds, what airports to divert to in an emergency, weather info, and more.

Cockpit Chronicles: Paper makes a plane fly
Takeoff speed... A pilot generally won't be allowed to fly the aircraft by the owners - unless it's his own - without some proficiency practicing with it - or nowadays, for big aircraft, a simulator. Thus you should know the rotation speed (lift nose) take off and climb speeds, approach speed for landing with various flaps, etc. Just before you do it is not the best time to be looking it up these details. Of course with commercial pilots flying big jets (or back in the day, props) they would likely be only flying one or two types of aircraft, so they would have been very familiar with key numbers, as well as the controls.

But not necessarily. The only large airplane crash I saw was about 1970 in Toronto (and from miles away, you could see it halfway across the city). I read an analysis of the crash a few years ago. Apparently with a DC8 there were different flap lever configurations, and in this case a copilot familiar with the wrong setup deployed the air brakes (?) 50 feet up. The plane bounced, dropped an engine, and flew off to attempt a go-around. You could see a big ball of flame going across the horizon until it finally crashed. All because two versions of the aircraft had different configurations of a key lever.
  #32  
Old 10-21-2017, 11:05 AM
LSLGuy LSLGuy is offline
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Originally Posted by thirdname View Post
Yes, here's a video where a pilot shows a large folder of information he receives before a flight. It has things like takeoff speeds, the planned route with altitudes and airspeeds, what airports to divert to in an emergency, weather info, and more.

Cockpit Chronicles: Paper makes a plane fly
Our standard joke has always been "We can't leave until the paperwork weighs more than the airplane." The other version, since it's printed as a long strip on old-style fanfold paper with the pinfeed holes along the side, is "We can't leave until the paperwork is longer than the airplane."

The fixed-size content ends up being about 8 printed pages. Then comes the variable content which depends on how long the route is and how convoluted the weather, plus whether the airports at either end are big complicated places or small Podunk fields. A quick hop between two small airports is worth probably 4 extra pages. A 12-hour jaunt between two major city airports is more like 30 extra pages.

We're in the midst of switching all this to iPad downloads of the same text content in lieu of physical paper. Plus a new and vast pile of weather info downloaded in graphical form. So we're carrying less paper, but actually have more total preflight info to supposedly review in excruciating detail and be fully cognizant of.

We're also moving into having WiFi in the cockpit so we can even update all this mound of info in near real time as needed. Which is not really useful for a short hop but can be invaluable when you're arriving some place 12 hours after your paperwork was printed and in the meantime the weather has not been behaving as predicted.
  #33  
Old 10-21-2017, 12:05 PM
Robot Arm Robot Arm is offline
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Do you know if he liked it? I've been flying it for the last 6 years and I don't know if I like it or not. A bit of a love / hate relationship.
You know, I never thought to ask him that specifically. Part of his job was to pick up new RJs at the factory in England, do an acceptance flight on behalf of the airline, take part in a conference call to transfer ownership, and ferry them to the U.S. They probably still had that new plane smell.
  #34  
Old 10-21-2017, 12:33 PM
Daylate Daylate is offline
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It's interesting that Charles Lindbergh made a solo flight from New York to Paris in 1927 without ANY of that stuff. Couldn't even look forward without using a small periscope.
  #35  
Old 10-21-2017, 02:03 PM
Sam Stone Sam Stone is online now
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Before GPS, we had other navigational aids such as LORAN, ADF, and VOR beacons. Then there is good old pilotage, which is using a combination of dead deckoning and landmark/terrain spotting.

I used to participate in an annual air rally which was a precision flight planning/dead reckoning navigation contest. It was common for pilots to fly the three-legged route a couple of hundred miles long and land at the destination within a minute or two of the flight plan, using no aids other than their MKI eyeballs and a winds aloft report. And if you didn’t have the winds aloft or they were inaccurate, you could calculate that in flight and adjust your flight plan accordingly using a circular slide rule (the E6B flight computer or ‘whiz wheel’).

Last edited by Sam Stone; 10-21-2017 at 02:05 PM.
  #36  
Old 10-21-2017, 04:13 PM
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Some great information, all. I wasn't aware the weather reports and predictions for aviation were accurate enough you could trust one set of data for more than a few hours. Or are variations that important? Does it matter if your headwind (or crosswind) is 20 knots rather than the 10 you expected?

Also, how accurate is the saying "If you can see it with your eyes, you're probably too close" ('it' referring to another aircraft)? I assume it's mostly for the big airliners.
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  #37  
Old 10-21-2017, 05:09 PM
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.But y'all are saying you calculate an estimated value then adjust it as needed to get the result you want. Also, a lot of the stuff is just efficiency-maximizing gravy.
.

I think that it's clear that up through WWII, if you didn't get the result you wanted after estimation, you just died.
  #38  
Old 10-21-2017, 05:26 PM
LSLGuy LSLGuy is offline
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Enroute crosswinds are essentially immaterial. Except when unusually large changes over a short distance are associated with turbulence. An unexpected headwind increase of 10 knots would put you 10 miles behind the plan at the end of an hour of cruise. 10 miles represents less than 90 seconds' flying. Even over a 12 hour flight it's only going to add up to about 18 minutes. We have more slack than that in our planning. So a 10 knot error in headwind expectations is also negligible. 20 or 30 knots off forecast starts to matter. But is exceedingly rare these days.

Where unexpected winds matter is in arrival. A common scenario is something like the wind blowing from the east until a front is expected to pass and thereafter the wind will be from the west. At the time of frontal passage there may be strong gusts and there may be a 10 minute pause in operations while they switch which direction the airport is operating. If you were expecting to arrive before or after and instead the front arrives just when you do, you'll maybe get wrapped up in the delay. In the US at least, many fronts also come with thunderstorms which can stop an airport for an hour. Overall the weather folks are real good at predicting what will happen where. The when is often the weakest part of their predictions.

There are also a few airports where winds strongly affect throughput or whether the long or short runway is available. Or whether the wind-compatible runway is equipped for crap weather landings or not.

Naturally when operating into unsettled conditions, or into airports that are especially weather sensitive, everyone involved at HQ and in the cockpit are paying extra attention.

Another issue more common in fall or winter is temperature. If the temp drops enough in humid conditions fog will form or rain may turn to wet gloppy snow. Any time the temp forecast shows conditions should be just on the warm side of fog or freezing that's a wakeup call.


As to seeing other airplanes we do it all the time. In cruise they go by big enough to know what kind and read the logos. What they don't do (or at least really, really shouldn't do ) is go by close at the same altitude. On arrival and departure at a hub it's very common to see a handful or airborne jets at a time, and be navigating yourself to follow or avoid one or another.

Naturally, how far away a big jet can be seen depends on the clouds. In hazy or cloudy conditions jets can go by 1000 feet above or below with zero lateral offset and never be seen. All we see is the dot on our traffic scope getting closer to our dot at 1000mph until they cross through each other. OTOH, on a very clear day where jets are dragging contrails we may see each other 100 miles out; a full 6 minutes before we pass.

Last edited by LSLGuy; 10-21-2017 at 05:30 PM.
  #39  
Old 10-21-2017, 05:30 PM
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[snip]

There's an apparently well-known phenomenon among student pilots and their instructors: Vastly many beginning student pilots are phobic about learning to use the radio. It seems that there's so much for the newbie pilot to think about, it fully occupies all their mental bandwidth, and talking on the radio (with its somewhat contrived and scripted artificial language) alone takes up a shitload of mental bandwidth (for a newbie). Taken all together, it's just too much mental overload for a beginning pilot to fly the plane during the pattern and landing, and talk on the radio at the same time.
I was on a small two-engine prop plane in Venezuela once, returning from a trip to Angel Falls. I want to say it was a Dornier because they're sort of funny-looking and it stuck in my head. I was in the aisle seat in the front row and the cockpit door was open. It was clear that one pilot was a vet and was explaining things to the other--I don't speak enough Spanish to have followed exactly, but the older guy would point to an instrument and say something, the younger guy would clearly be asking a question; there was occasional reference to a printed manual.

Then we begin to descend. At this point the pilot unplugs his radio transceiver, which is on his side of the plane, and hands it to the junior guy. The senior guy is looking at something and doesn't see what I see: Instead of plugging in the transceiver on his side, the trainee just sets it down next to him, then takes the stick. I'm thinking, that can't be right. But what am I gonna do, interrupt two pilots to ask questions in a language I can't really speak, about flying a plane, which I don't know how to do?

The trainee is now flying with occasional comment from the senior. But I can see out the front window, and it looks to me like our descent is really steep. The radio starts spitting out questions or advice from the ground. When the younger guy doesn't respond, the older says something angry to the younger guy, like "why don't you answer?," in response to which he holds up the disconnected transceiver and shrugs. The older guy, instead of doing something, starts berating the younger guy. Meanwhile it looks to me like we're pointed straight at the ground. I don't remember being afraid, but I thought we were going to crash for sure.

Finally the older guy grabs the stick himself, pulls us up sharp, three hard bounces and we're on the ground safely.

Last edited by TSBG; 10-21-2017 at 05:31 PM.
  #40  
Old 10-21-2017, 07:12 PM
Richard Pearse Richard Pearse is online now
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Some great information, all. I wasn't aware the weather reports and predictions for aviation were accurate enough you could trust one set of data for more than a few hours. Or are variations that important? Does it matter if your headwind (or crosswind) is 20 knots rather than the 10 you expected?
As LSLGuy says, 10 knots is nothing. The only time I get concerned by the en route wind is when there is a very strong cross wind. A small change in wind direction can cause a large change in the head / tail component. If you're tracking north with a 120 knot crosswind from the west, a 15 change in either direction can see a 60 knot change in head / tail component. If the plan was based on 30 knots tailwind but you actually get 30 knots of headwind then you may need to think about fuel a bit more seriously than you normally would.
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