We often get customers complaining about a misplaced sticker on a livery, a missing exit door in a particular variant of a the 737-900... That type of stuff is easily verifiable. But for things like the airplane not behaving in a way they expect in certain conditions, or perhaps a wrong approach speed or angle, discussions usually start with:
"We tuned the airplane based on information available to us at the time we built the airplane. We are happy to make any changes based on an actual report from one or more pilots flying on this airplane, or better yet, the aircraft manual if you can get your hands on one."
The discussion usually ends there :)
One we get often is about why it's possible to do a barrel roll in a jet liner in Infinite Flight. We simply point them to the video of that test pilot who did one in a 707 ;-)
The reason most aircraft are incapable of flying upside down isn't usually due to stresses on the airframe, it's because the fueling system relies on some form of force pushing the fuel through the bottom of the aircraft. A 1-G barrel roll does exactly that.
There's some interesting trickery done with carbureted aerobatic aircraft to let them fly upside down for an extended period of time, including special valves which shut off fuel flow to the bowls when gravity isn't in the direction they expect it to be, so the aircraft won't lose that fuel back into the fueling system (or out the top of the engine) and can run for a bit on that fuel in the carburetor bowls until the plane is righted.
Although it's a low positive G maneuver it's not 1G, only straight and level flight is 1G, everything else requires a deviation from that to change direction. Wikipedia says it will vary between 0.5 to 3G throughout the maneuver which should be possible in almost all aircraft as it keeps fuel flowing and isn't a major stress on the airframe. It's probably even possible to do it at no more than 1.5G if you do it large enough so that it's even comfortable and not particularly noticeable for the passengers that don't look out the window.
I'm a private pilot who has done aerobatics, exactly 1G doesn't work - and it's completely unnecessary (though you can stay pretty close to it, so that someone with their eyes closed would not know they were rolled).
But just about the video as "proof of 1G":
As long as you stay positive you are fine, even psychologically with passengers not used to it. The real turning point, in real effects as well as psychologically, is when you approach 0G, the feeling only starts at less than 0.5G when you begin to feel more and more weightless.
When you go even slightly negative it becomes a completely different matter, both in terms of real effects (fuel, oil, lose stuff flying around the cabin) as well as psychologically: Even though you made the harness extra tight with as much force as you could muster in preparation for an aerobatic flight with negative G forces, when you get here it feels as if you hang upside down in the harness and the seat is miles away from you, as if you dropped a few centimeters and now literally just hang in the airplane.
I (in my small and somewhat underpowered aircraft) go below 1G when I get close to the top, because if I tried to maintain 1G the nose of the airplane would have to drop (towards the earth in that position), and I want to keep that at a minimum, so that I don't end the roll with the nose in too much of a nose-down attitude from which I will have to pull out.
Here is an image from my flying some years ago, in a Grob 115C Acro (rented from Attitude Aviation, Livermore, CA, ca. 2002): http://i.imgur.com/Rd5VW3R.jpg (the inside of this airplane: http://i.imgur.com/4bwJn13.jpg)
EDIT: (after reading some comments) To me a roll is over when the airplane is back to straight and level, after 360 degrees. So my statements are for that interpretation of the word "roll". And my frame of reference for g-forces are the people on board the aircraft.
But as the video demonstrates quite well, the first phase of a barrel roll requires pitching up into a gentle climb. This is physically impossible without exceeding 1g at any point.
You can stay arbitrarily close to 1 gee, given unlimited time and altitude, but you can't stay exactly at one gee throughout a barrel roll.
Here's the difference, once the plane's wings are level with the horizon, the roll is considered to have been completed. The rest (regaining a stable pitch) is recovery.
Yes, you are correct that the aircraft's velocity is not maintainable after the maneuver has been completed, and must incur positive G forces to regain level flight, but it's not technically part of the barrel roll.
EDIT: As I noted in another response (in which I go into a lot more detail), the pilot probably doesn't even have to take any action to negate the downward velocity component; the change in the angle of attack (the angle at which the wing intersects with the airflow) would naturally increase the amount of lift being generated by the wing, at the cost of more drag.
I suppose it's high-school-physics possible to fly a 1 gee helical path (the "barrel roll") centered around an orbital zero-gee trajectory...
Imagine for a moment a zero gee orbital trajectory at a low enough altitude that you can still generate aerodynamic lift from the atmosphere. (Here we handwave away all the pesky frictional heating, because we're deep in the thought experiment world of perfectly spherical cows of uniform density.) Now imagine a helical "coil spring" shaped path with that orbital trajectory running through the center. "All" you need to do is get the diameter and spacing of those helical coils right so your acceleration around the coils needs to be 1G, while your averaged out path coincides with the orbital zero gee trajectory.
(An aircraft with sufficient speed, fuel capacity, heat shielding, and whatever else I've glossed over - is left as an exercise for the reader...)
Imagine a fighter jet flying circles around an airliner as it follows it along - with the fighter pilot flying at just the right radius and speed that it's accelerating at 1 gee for the turn (so they'd be "feeling" 2 gee as they pass under the airliner, and zero gee as they loop over the top of the airliner) using a helical "barrel roll" path - and at the same time "keeping up" with the airliner along it's path, so if you were sitting in the airliner looking out it'd look like the fighter was flying circles around the long axis of the fuselage.
Now imagine the fighter pilot does the same trick following the vomit comet - as it flies its parabolic arcs which gives it's occupants 20-30 secs or so of "zero gee".
You're neglecting two potential sources of upward acceleration. One, the turn itself, or in other words air resistance: if you stop turning when you're pointed straight up, clearly you're going to go up, not down (at least to start with), which means the turn accelerated you upward. And two, any forward acceleration provided by the engine while "forward" isn't horizontal.
(I don't know enough about aerodynamics to actually determine how a barrel roll actually works, though, only enough to contradict your post :)
This is quite easy to do when you realize that the plane can (and will) lose altitude and transfer ground-relative horizontal momentum for the vertical.
I mean downwards towards the floor of the plane of course, not the center of the earth. mikeash has already explained much better than I could why you can't keep 1G from the point of view of the passenger and do a normal barrel roll from/to level flight. It seems easy to have a path that does it if you allow it to finish in descending flight.
Yes, but you're not going to like the outcome.
Trying to come up with a better explanation for the first.
EDIT: Try this on for size:
Given - the force imparted by the wings is 1G (enough to cancel the force of gravity), and will always be pointed straight through the roof of the aircraft. The pilot takes no action to increase the amount of lift. The G's are measured from the frame of reference of the passengers in respect to the aircraft. Rotational forces are not considered - most people are unable to kinesthetically perceive any rotation which occurs at less than 5 degrees per second, and don't realize that they could be upside down and still feeling like they're right side up. It's why instrument training involves so much instruction and reminders to trust the instruments, not your body.
The maneuver is initiated by rolling the plane (clockwise, with respect to the pilot) with the ailerons. Since no effort is made to change the amount of force being generated by the wings, the downward component of that thrust (as measured from an external reference point) will lessen, allowing the aircraft to start accelerating downwards while also accelerating to the right. The force felt by the passengers is still exactly 1G - the force created by the wings, and it is still pointed vertically through the plane. Since the downward component affects the passengers and plane equally, there is no measurable effect on the G forces with respect to the passenger's frame of reference.
The aircraft reaches 90 degrees, and is accelerating to the right at 1G, and downwards at 1G. The downward force is not felt by the passengers, again because their entire frame of reference is accelerating at the same speed, only the force pushing them into their seats.
The aircraft reaches 180 degrees, and is now accelerating at 2Gs downwards. Passengers are still feeling only 1G of pressure from the seat.
270 degrees - the acceleration to the left cancels out the previous acceleration to the right, passengers are still being just pushed into their seats.
360 degrees - the maneuver is complete. The plane is significantly lower and some distance to the "right" of its original position. Their velocity now includes a significant downwards component.
Now here's where things perhaps become a matter of semantics - pilots would consider the barrel roll to be completed at this point, and they simply need to recover from their new orientation. Of course, this will probably require little to no input from the pilot, it will simply happen naturally due to the changed angle of attack induced by the downward motion increasing the lift generated by the wing.
An aircraft which is freefalling will be experiencing 0G's in that downward direction, but if the aircraft's wings are creating 1G of force perpendicular to the force of gravity, the only forces experienced within the frame of reference of the aircraft is that 1G sideways.
He said he is experienced enough to maintain 1.0 to 1.5G throughout the manoeuvre, and the most of the time, the weapons guys in the back of the plane who are usually 'heads down' and don't have big windows to look out of, don't even realise they were inverted for 10 to 15 seconds.
He said he has a standing wager with them when they land, and if the back seaters can accurately tell him how many ridgelines they crested inverted correctly, he buys them a beer. He told me he hardly ever has to buy.
Try standing on one leg. Then close your eyes. Or try walking in a very dark but not completely black room. And then close your eyes. Your balance sense might tell you very strange things and if you haven't trained for this, you might fall.
Oh, it can also tell you you're tumbling wildly when you are actually going completely straight. Really disorienting.
Well, kinda. The trick is that you have 1G downwards constantly, which can be reduced by initiating a descent at the same time you introduce other directional changes. Rotation (the major component of a barrel roll) does not impart G forces, as recognized by the term.
I'm sure few to zero pilots who can keep it at 1G exactly throughout the maneuver, but it is at least theoretically possible (so long as you don't mind losing altitude via the maneuver).
This isn't possible. In straight and level flight you are experiencing 1G acceleration. To be able to change the plane's orientation in any way you need to impart some acceleration to it and thus deviate from the 1G. For example initiating a descent requires an acceleration downwards which will be felt by the passengers as less than 1G. If you finesse it enough and do it big and wide enough you can probably maintain it within a tolerance for what we consider to be 1G but it's not possible to stay at 1G exactly.
But it would be cool to see if there's a theoretical path that we can recognize as a barrel roll than keeps exactly 1G of acceleration in any direction needed.
You can experience 1G while banked 90 degrees by pulling up slightly. However, the plane will be losing altitude as the wings are not generating lift.
Of course, it would point in a different direction, but the magnitude would be 1G.
Hell, i think you could easily develop an intuition for it.
Electrical planes have a weight issue with the need for batteries (or humongous wings covered with solar panels). Petroleum products, for better or worse, still have a huge advantage in the energy/weight department.
There are ways to ensure fuel delivery, but the problem certainly isn't unique to carbureted engines, only the particular issue of managing the fuel in the carburetor bowl.
Note: this is a couple or more decades old knowledge... Modern electric powered rc planes and builders don't have this problem to deal with.
As a side note, at 30 degrees AoA the aircraft will not be able to continue flying anyway, the wings will have stalled well before that, and the pilot would be made painfully aware of this fact through stick shakers, aural warnings, and very rough tail buffet.
I'm a flight test engineer, so this stuff is what I get to do for work! :)
(Unintentionally reduced spoilers due to having forgotten many details of the film.)
Look again at the actors. Smiley never stops studying the others' face, while the other looks scared, nervous, shifty, and guilty the entire time. Even without context you should be able to pick up that Smiley is cool as ice, and that the other man has something to hide.
The PLI is capped at 30 degrees pitch, but that does not mean that the plane would stall at 30 degrees. You could climb much steeper than that if you had enough speed:
> However, the PLI also is limited to 30 deg of pitch attitude, regardless of AOA. If AOA or AOA margin to stick shaker were to be used as the first and primary focus of the flight crew during windshear escape or terrain avoidance procedures, extremely high pitch attitudes could be reached before stall warning if the maneuver is entered with sufficient speed. Therefore, the PLI shows the lesser of either margin to stick shaker, or 30 deg of pitch. (http://www.boeing.com/commercial/aeromagazine/aero_12/attack...)
Nevertheless, at least according to some Wired article, one of these steep takeoffs was done at a little under 30 degrees. (https://www.wired.com/2014/07/watch-test-pilots-push-the-new...) I guess the pilots use the PLI to judge their pitch attitude.
Boeing also released a video of the pilots rehearsing the routine. There's an overhead view of the takeoff - that's a lot steeper than 30 degrees, unless it's a perspective trick.
EDIT: 50-55 degrees seems to the actual pitch angle.
As long are you have enough thrust, airspeed and no system preventing you to go above a certain pitch or AOA, then the plane should fly just fine...
or a C-130 taking off and landing on an aircraft carrier:
isn't modern flight awesome?
That said, standing on a vinyl tiled deck in the peak angle point of one is a trip!
I wonder what systems do you really simulate.
The loss of altitude the moment the wings are vertical is crazy.
Personally don't think this should be a point of pride.
They usually don't find it because it is based on "shower curtain" type of sources. ("my brother told me", or "this other sim behaves this way")
" Hit severe turbulance over seattle on route to alaska. Didnt have seatbelt sign on. One dead, several injured. Am playing in-flight movie but passengers still angry. Should i serve meal early or wait until closer to destination?"
"I wonder how realistic the operations of the virtual airlines are. In the game, do you get to have local police come on your plane and beat up your passengers and drag them off before you take off on your flight route?"
And, while I am German, I have not seen Ryanair Checkin Simulator 2000. I'll have to check the section behind the curtain, though. May have been x-rated for excessive violence and unsatisfactory kink.
Of course, it's easy to create it yourself in Simulator Simulator 2017 if you have the "Extreme Queuing (Britain)" expansion pack.
The executive summary of the incident seems to be that there just weren't any adults in the room. One can easily picture gate agents, flight attendants, and the aviation department staff involved basically feeling that they must follow instructions, being worried about breaking policies, being written up, whatever.
You'd hope that if the whole thing were put in front of a pilot, they'd perhaps take a more wholistic, pragmatic, problem-solving view, and try a few other options first. Seems like almost anything would have been better - talking to the passengers, getting everybody to leave the plane and reboard / sort it out in the terminal, cancelling the flight, getting a bigger plane, putting the airline staff on a different airline, anything. If a pilot couldn't come up with a better solution to something like this, I'd worry how they'd fare in the air with a mechanical emergency.
I'm still kind of skeptical that the pilots could be completely oblivious about it though. You'd think that if something is serious enough for a flight attendant or gate agent to call law enforcement, and get them onto the plane, then they'd tell the pilot about it too, if only as a courtesy or practical measure so they're not surprised about the noise or banging on the door. Also, at some point the pilots are going to have manifests of passengers vs crew, and that would change, so you'd think they'd see that happening, since the plane was fully boarded it seems possible they'd have had the first manifest, and wonder about / be annoyed about late changes. Or, maybe they'd simply see the law enforcement folks get on, or hear the call on the intercom / radio, etc.
I'm more inclined to think that the situation was misrepresented to them ("we have an unruly passenger, but we're taking care of it"), and they took it at face value without asking any questions. Will be interesting to see what comes out.
 [Video] http://www.msn.com/en-us/tv/video/united-pilots-issue-statem...
Used to have a different game back in the day, Hard Truck iirc, which was a lot more game-y - areas you couldn't reach with the one truck, offroad sections, truck racing, etc. Very satisfying at the time.
I also appreciated that I could walk away at any point and pick it up later. I didn't feel "trapped" having to finish a mission like too many AAA games. Well worth the ten bucks in my opinion.
They should not have treated him in that way, they should not have been violent, but so long as the pilot wanted him off he was obligated.
So no, I won't "take it from a lawyer".
A lot of those rules kick in only after the door is closed, or when the aircraft pulls back from the gate.
About halfway through the flight, the gamer remarks that the pilot is wrong, and not taking the best route for the flight. The flight sim path and real plane are going in slightly different directions. They try to tell a flight attendant who assures them know "the pilot knows what they're doing." The remaining half of the flight they complained to either the author or other attendants, acting like they knew more than the staff.
They never got to finish their flight-sim though, because the real plane landed 20 minutes ahead of schedule. I guess the pilot did take a different path after all!
My favorite is when a customer was raising hell because London International Airport (YXU) wasn't appearing under the city listing for London, UK and demanding it be added immediately. I had to tell them you don't fly there... it's located in Canada.
We also have airports with "CZ" (eg. CZBB).
I am not sure what the difference (if any) between CZ vs. CY codes is. Probably just sticking with convention (begin with Y or Z because everyone else does).
But Y is heavily Canadian. We should all just start our own airport. Sounds like a good way to learn about naming. I imagine we will want an airport code staring with YC, so it'll have to be in Canada :P
The worst part is that after you land at YXU you're in London, Ontario.
(I lived near YXU for three years).
My neighbor at the time was a commercial pilot, and I asked him about the difference. He says that anything else that the airline or anybody else tells you ahead of time is only tentative. The final call on the route is made by the pilot on departure. He's considering things like wind speed and direction along the way, weather along the route, and weather at potential intermediate airports should an emergency arise.
Bonus fact. He told me that he dislikes flying the newer Boeings because of the location of the cupholder. On other planes it's closer to the plane's major axis, but these planes put them farther away. This has the effect of magnifying the plane's motion, and leads to coffee spills.
Regardless of the circumstance, my apologies & condolences to the friends & family of the crew and any passengers. From your short description, this seems like an easily avoided accident and I hope actions are being taken to prevent a recurrence.
Probably the most shocking part is that there was a lighthouse on this island, which was operational at the time. This is shocking both because it should have been blindingly obvious to the pilot and crew that they were flying toward a lighthouse, and also that an island significant enough to have a lighthouse on it would not be on a digital mapping system. It's on Google maps - https://goo.gl/maps/Xdt7rzUErX42, even has photos and information. This is not some insignificant rock
How an aircraft mapping system can have such a huge omission is just mind-blowing
Something that is geographically notable but quite small, vertical and isolated (like Rockall) may very well also be omitted from that version of the EGPWS database.
NB Blackrock is a designated navigational waypoint on the standard charts etc. which is why they were flying straight toward it on autopilot.
Why are "small" and "isolated" good criteria for omitting something from a database of elevation geometry? It's evidently big enough to crash into and cause loss of life.
If the source is some kind of DEM (digital elevation model) data, it will be a raster of elevation values at some limited resolution, so necessarily just samples of elevation. With a relatively small island/rock, the full height could be missed, and possibly then even further reduced by filtering (i.e. smoothing of DEM values, either in the process of measurement or some kind of processing). That likelihood is hinted at by this quote from the manufacturer:
"Honeywell’s terrain data is sourced from our supplier [named supplier]. It is a digitized topographic map derived data set. It does not include Black Rock. We have looked at alternate sources, including SRTM and ASTER. While Black Rock is present in these alternate data sets, the actual altitude of Black Rock is considerably higher than what is indicated in these alternate data sets."
The data sources they refer to:
Again, not coming to any conclusions from this.
Preliminary accident report is at .
What was the the MKI?
Nah, I am going to go with Optically tested and Corrected vision. A uniquely human trait.
> In relation to Black Rock and its Lighthouse the EGPWS manufacturer informed the Investigation that “The lighthouse obstacle is not in the obstacle database and the terrain of the island is not in our terrain database.”
The cause was a blind over-reliance on a single chart which did not show any navigation hazards in the area. Other charts available to the crew had indications of the presence of a seamount.
> The preliminary report by AAIU investigators found that the helicopter had hit the island, which was not registered in the craft's mapping system and was only identified by a crew member only 13 seconds before impact.
He used MS Flight Simulator to train to get his license back after several years of having let it lapse and to train for his IFR certification. To this day, other than watching him play Pac Man at K-Mart in the 80s, I had not before, nor since, seen him play any video game on his home PC.
 Most small plane pilots have basic licenses - VFR - or Visual Flight Rules. IFR is for pilots who have instrument ratings. It's not all-together rare, but not necessarily common and is usually reserved for pilots who fly in a more professional capacity, as my father did. He was certified to fly a single engine aircraft (he flew a Cherokee -- 6?) and had more hours on him some years than some commercial pilots.
Now THAT is a domain I haven't seen in a long, long time.
X-Plane 11 looks absolutely fantastic, thankfully. Might be about time to pay FSX a final salute, and nice to support X-Plane as a reward for standing up to patent trolls.
That's kind of a weird stipulation: fun is prohibited.
Development stopped with the dissolution of ACES, the Flight Simulator team, but Lockheed acquired rights to continue to develop MS ESP, which eventually became Lockheed's Prepare3d .
It's older than any of the Office components, too.
The reason why Ctrl-F means forward and not search in Outlook is bug report from Gates.
complaining about wasted productivity, while commenting on HN
That it turned out to be a nonsense issue is immaterial to that judgement.
This kind of story makes it worthwhile, though. At the end of the day, you go home laughing instead of crying.
During WW2, British, and later, American forces set up base in Iceland. On some of the maps they had created, items of note had been added with symbols. This included lighthouses and there were little lighthouse symbols littered around the coast. However for some reason there also was a lighthouse symbol in the middle of the Icelandic highlands, far from any seashore.
The explanation was that this supposed lighthouse was by the volcano Askja, who's largest crater is called "Víti" (Hell), while the Icelandic word for lighthouse is "viti". Since English doesn't have the accented letter "í", they would have been spelled the same in English.
I could have sworn this was a true story up until now when I tried to find sources for it, but came up empty. In any case it makes for a good story.
I really liked that product, and it has the legacy of being one of Microsoft's oldest product lines.
There's also a very vibrant community about adding mods and additions onto Flight Simulator, I'm really curious as to why it was killed off. Was the the Flight Sim team really that big of a drain on Microsoft's balance sheet?
Just really sad about spending hours on a product dying off... :(
From an external perspective, it seems most likely due to IEB's leadership at the time wanting to focus all their resources behind the upcoming Xbox One, in hopes they could replicate the success of the Xbox 360, and the misguided belief that PC gaming was dying out.
Neither of those bets worked out particularly well for them.
> Was the the Flight Sim team really that big of a drain on Microsoft's balance sheet?
Rumor has it that it consistently turned a small but not insignificant profit.
Apparently it's budget cut, which is weird since we know MS are always swimming in cash...
Great nugget to pull out if you have a manager with a penchant for stating the obvious!
 - https://blogs.msdn.microsoft.com/oldnewthing/20100705-00/?p=...
Or, as I learned over time, trying to save a drowning person without the help of a flotation device just might pull you down into the abyss as well, good intentions not withstanding.
The why the customer believes it to be a bug can be more important than the bug's description.
Hey, we've got company: in the MS blog's comments, there's a fellow who archly informs the peasants that "I usually archive & star (bookmark) articles that have an amazingly interesting or peculiar technical aspects. With this one, I’ll gladly make an exception."
Dammit, Raymond Chen is out of pocket for a refund on that guy's subscription.
?!? That sounded like a positive review from somebody who liked the article. He says it's neither amazingly interesting nor technical, but still good enough to bookmark.
Bonus points that it was written by Raymond Chen, I am a longtime fan of his writing.