Comments by "Mikko Rantalainen" (@MikkoRantalainen) on "Mentour Now!" channel.

  1.  @alanevery215  Successful as in meeting minimum bar required to build Boeing airplanes.
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  2. 11:40 As a software developer, I would be really unhappy to find out that a piece of untested software went into production. Especially in something as important as aviation. If you don't have QA people to verify the software, you simply do not upgrade the systems on the fly! If you plan upgrading the software during the weekends, you must have QA people working during the weekeds, too. Also, a well running software teams should be running automated regression tests. That is, for every bugfix you ever implement, you write an automated test that verifies that the fix still works and there's no regression on that part. This is because many software bugs are result of developer misunderstanding the system and once a single misunderstanding has happened in some part of the system, the changes are pretty high that some another developer will have similar misunderstanding in the future.
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  3. Seems legit!
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  4. So, basically any silicon or TPU case which covers all the edges of the phone should be equally good for this use case? If you don't mind the usability issues, something like Otterbox where the protective edge comes off the screen quite a lot would guard the glass pretty well. Of course, that also makes all the touch gestures starting or ending at the edge of the screen next to impossible to execute.
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  5. With the incidents happening frequently, it seems that the passing minimum bar for both pilots and ATC should be increased, especially for radio communications. And the method of having two planes share the same runway (one landing and one about to take off) should be stopped.
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  6.  @johnburns4017  USA won the marketing race to space because we still haven't beaten "the first human on a natural planet or satellite" achievement. Next step on that ladder is "First human on Mars" and we are still pretty far from that. And for general public the marketing race is the only thing that matters even if geeks could consider other factors, too.
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  7. Boeing couldn't add extra information for pilots about MCAS or make it redundant because either of those actions would have meant it couldn't have had the same type certificate as non-MAX 737. And as this was already promised by the marketing department, they choose to take the risks. I see this as yet another example how you shouldn't give marketing department any ability to override engineering. Unless we see a change in this part of the Boeing culture, there's no way for Boeing to build reliable aircraft in long term.
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  8. Great analysis as usual! As a side-note, you should ask your video editor to deinterlace any interlaced source videos before mixing them into the final product. The Rolls-Royce clips in this video have combing artefacts because of missing deinterlacing.
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  9. I appears that he was daredevil to the bone and planning that far ahead doesn't compute for people of his kind.
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  10. And if it hits some kind of bush instead of landing directly on grass, there's no need for a case at all.
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  11. And definitely not let the aviation companies to decide if the existing type certification for the older model is usable for next model. This far MAX has had at least features such as MCAS and cockpit door opening by itself on depressurisation that haven't been disclosed to pilots on "no need to know" basis – I would assume to make FAA accept that no additional training is required.
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  12.  @razvanlex  When you meet somebody with a cracked screen, do you think they have been living within bushes and soft grass. Or in concrete jungle?
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  13.  @tradingmedic  They were doing this stunt in public airspace. It's no different from asking a permission to record a car crash in your local city for a movie, not getting the permission and doing the crash anyway. If you cannot get permission for the location you want, modify the experiment or switch location. Or do it on private property (in the US, I guess that would be some military reserved airspace restricted from public).
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  14.  @Maker_Mikey  I agree. The trick that Boeing did with MCAS was that they declared it is not a critical system so it didn't matter if it had failure rate above 10e-9. In practice, it was a critical system demonstrated by two big crashes.
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  15.  @norlockv  If I've understood correctly MCAS couldn't use redundant sensors because FAA rules define that any system with redundant parts shall be considered critical and must be included in pilot training. As Boeing marketing department had already decided that MAX shall not have any additional training requirements, Boeing had to become creative. The solution they selected was to not have redundant sensors and therefore the system wasn't critical and therefore pilots didn't need to be told about it! I have trouble understanding how any system that can affect flight surfaces can be considered non-critical, no matter how it's implemented?
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  16. If there's an active noise cancellation system, a broken microphone of such system combined with the noice cancellation system might be a possible solution. If this re-occurs often enough, creating a multi-microphone recording of the cabin would allow pinpointing the source of the audio. I'd expect it to be the PA system, but in case this is some kind of prank, it could be some kind of portable speaker somewhere in the cabin, too.
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  17.  @sarthakmohanty997  I wouldn't be surprised if it turned out that Boeing management has similar problems as NASA did with the shuttle. If I remember correctly, NASA had a problem that engineering thought that there's about 1 in 100 change for life loss for any given shuttle mission (that is, the shuttle is 99% safe) and the management thought that there's about 1 in 1000000 change for life loss for any given shuttle mission (that is, the shuttle is 99,9999% safe). If you assume that the risk is 1 in million, you may get less strict about the details such as outdoor temperature and humidity during the launch or QA verification steps needed for the door plug.
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  18.  @ironcito1101  3 mm thick case might be enough even with somewhat slow terminal velocity if crash direction is perfect. That is, no bending forces from the hit, glass never touching anything hard. I wouldn't be surprised if the phone can take at least 100g without breaking . If we assume that the terminal velocity of a smartphone is around 50 m/s and the 3 mm bumber being flattened therefore takes about 0.00006 seconds, the resulting g-force for the stop is about 85g. If the hit is corner first, the g-force may bend the phone which will obviously crack the glass parts.
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  19. Yet another MAX "pilot's don't need to be told about this change" feature, right? I get upset when I don't have a truthful changelog for the software I use, I would expect pilots to be asking for even more!
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  20.  @johngunderson5463  MCAS was pretended to be an aid with an off switch, not a critical system, so it couldn't cause catastrophic outcome in theory. And you cannot have no single failure if you consider failures such as tail snapping off the plane. You have to draw a line to some probability, always.
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  21. The total amount of fuel saved with engine brake (for 100% ICE truck) is maybe one litre of fuel per hour if executed perfectly. However, if you try to drive using only engine braking, you'll be planning your approach to intersections and traffic lights a lot more and if that planning avoids even one full stop, the amount of fuel you save is quite a bit. That is, if you mentally limit your typical braking power to engine braking only, it will affect your driving style which will affect the fuel usage a lot. If you want to save a lot more fuel, drop your long haul speed from 80 km/h to 70 km/h. However, most drivers are not willing to take the extra hit in delivery time even if that would save maybe 20% fuel.
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  22. ​ @theephemeralglade1935  Yes, the original F-16 stick was intented to be like part of the aircraft where the whole aircraft magically turned with your hand forces alone. However, that turned to be somewhat incompatible with human psychology. I'd guess this is because you move along the aircraft.
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  23.  @BillyBoze  You have to remember that they wanted to do this stunt in public airspace. That's when you absolutely need permission from FAA.
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  24.  @miscbits6399  The space shuttle project was indeed pretty silly from the start. Raising any mass to the orbit is hideously expensive so having a reusable space shuttle with dry weight of 78000 kg was always going to be pretty bad plan. Assuming a low average $1000/kg for the fuel costs alone to get something to the orbit, the 78000 kg dry weight for the shuttle put minimum extra cost to $78 million per launch for the empty shuttle alone. Any real cargo would be on top of that. As a comparision, total cost for a single SpaceX Falcon 9 mission is 50–67 million USD.
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  25. Great points about how a flying wing design could work with the existing infrastructure. Airports, maintenance facilities and manufacturing technologies have been optimized for existing designs and flying wing design would need to be obviously superior to offset all the changes needed to support infrastructure. Otherwise, the changes needed to switch to flying wing couldn't be re-payed in any reasonable timeframe. That would make total cost of ownership of the flying wing less economical in long run. I'd expect the overall tubular design to stay in production but the blending near the are where the wings are connected to fuselage will be probably streamlined a bit.
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  26.  @MarkRose1337  Quick search suggests that you get 0.003 mSv/h of extra radiation at 30000 ft and yearly limit for nuclear workers is 20 mSv. Getting over the nuclear worker safety limit would require more than about 6000 hours per year above 30000 ft assuming normal background conditions on ground. I'd assume most airline workers do less hours per year. To put these numbers into perspective, yearly natural background radiation here in Finland is about 3.2 mSv per year. In the end, no amount of radiation is truly safe but the nuclear worker limit of 20 mSv is considered safe in practice.
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  27. TL;DR: It's not known if the airplane manufacturers have too poor selectivity for their radio altimeters. There's 250 MHz buffer between 5G and airplane radio altimeter frequencies but the assumption is that the airplane manufacturers used such a poor implementation that such margin may not be enough. (I would guess there was no other reason but cost saving to not have more accurate radio receiver in the airplane.)
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  28. 4:29 I think the reason to create synthetic fuel instead of using pure hydrogen in planes is to avoid building those big and heavy hydrogen tanks. I haven't seen any calculations but I wouldn't be surprised if hauling heavy hydrogen tanks in planes would be less effective than using somewhat less effective manufacturing process to create fully sustainable synthetic jet fuel on ground and using engines designed for jet fuel.
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  29.  @DuRoehre90210  I would guess Y2K happened so long ago that junior developers have born only later. If they are not interested in ancient history as a hobby, Y2K doesn't ring a bell for them.
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  30. 8:47 This video clip really demonstrates how huge the jet engines are nowadays!
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  31.  @kell7195  I hate the fact the bean counters are making the decisions, too, but never underestimate the inertia of the society at large. Many people are more conservative than they think and any kind of change (good or bad) is hard to accomplish fast.
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  32. 12:50 81000 lithium batteries is a huge pile. It's about equivalent to all the batteries for ten new Tesla Model S passanger cars. Having so much batteries in the cargo without required paperwork seems pretty insane!
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  33. Wow! Yet another example of MAX "pilots will not need any additional training" decision that was made by the marketing and management without discussing about the reality with the engineering. I would be very careful with any "pilots will not need any additional training" style marketing speech from any manufacturer in case of changes to the aircraft design.
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  34. I'd be pretty sure that the insurance company will not be contacted for this stunt. Those planes were considered consumables for this stunt.
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  35.  @marceloluizfigueira7208  The point of force feedback should be to help with edge cases when pilots make mistakes. For example, if you mostly have very weak feedback but the feedback is 10x when dual input is detected, you would need zero additional clues about dual input situations. If neither pilot never made any errors, you would never feel the dual input feedback mode in real world. Pilots are human, too, and no matter how qualified they are, they will be making mistakes. Safe operating procedures and redundancy are used to make flying still safe even when a pilot makes a random error. Unqualified pilots would make unlimited amount of errors and there's no way to create a safe system with such an assumption. I'm software developer and I truly believe in old joke: "Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning."
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  36.  @marceloluizfigueira7208  I totally agree that things should be like you described. However, in reality we have cases like Air France Flight 447 where supposedly trained pilots causes perfectly flyable aircract into the sea and caused 228 fatalities. Either the acceptance criteria for all commercial pilots must be raised much higher or we need to keep adding fixes to deal with bad decisions. I don't really think pilots are idiots but they will find new ways to make mistakes. The system should be designed to allow at least the known issues to be handled better than those are currently handled.
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  37. 17:33 "sealed bearing was incorrectly assembled ... unsealed side more suspectible to moisture" Am I the only one reading this as "bearing was actually installed backwards"? Where's the QA process that's designed to catch exactly this kind of problems? Surely there must be a process where every step is verified by at least one another human being or the aircraft parts wouldn't be that expensive?
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  38. Pretty much anything is possible but in case of commercial airlines, it must make sense moneywise. Turning an old 747 from 4 to 2 engines would definitely require new type certification and as a result, lots of extra expenses on training in addition to all the design costs and implementation costs. It's simply too expensive and the already old 747 doesn't have long enough remaining lifespan to pay the bill the long run.
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  39. If 747 is The Queen of the skies, does that make A380 the King of the skies? A bit overweight but strong.
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  40.  @secondskins-nl  I'm pretty sure a smartphone terminal velocity should be at least the same level as a human (~40 m/s). My point was that even if we assume 50 m/s velocity and 3 mm stopping distance, it's still "only" 85 g. That would kill a human but a smartphone should be able to take that much acceleration if the force is applied evenly to the whole body of the smartphone instead of only one corner.
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  41.  @MarkRose1337  Thanks for the reference. I quickly went through the paper and even though I might usually consider studies based on self-reported surveys not that trustworthy, this had big enough sample size that it probably doesn't cause problems. It seems that there definitely is higher amount of cancer for the airline crew. However, I'm not sure if that's correlation or causality. According to the Table 1, the 95% CI range goes from below 1 to above zero SPR (multiplier for the probablity of getting cancer) for nearly all findings. Biggest exceptions are skin-related issues and breast cancer. The breast cancer is indeed an interesting finding! It looks like the breast cancer is 1.5x more probable for airplane crew. But I disagree about skin-related issues. Cosmic background radition (which is the only cause for the increased radiation in airplanes) doesn't stop at skin like alpha or beta radiation so it should cause any type of cancer with similar probability. I think it's much more plausible explanation that working within airline allows accessing locations with lots of sunshine (and UV radiation) much more often than general population. As a result, majority of the skin-related issues are probably caused by UV exposure instead. To the credit of the authors, they did mention some of the above limitations in the paper.
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  42. Why didn't P&W simply manufacture ~300 new engines and swap engines instead of grounding the full plane? They could rent the replacement engine to the owner of the plane to allow the plane to make money while its own engines were under maintenance. If a single engine requires 250–300 days to fix, about 300 new engines should be enough to fill the whole pipeline for engine maintenance queue.
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  43.  @alexlowe2054  I understand that increasing the minimum bar cannot fix things if you're willing to let things slip. If minimum bar is raised and if qualified staff cannot be found, the airport must be closed. Nowadays you let the minimum requirements slip because you're "forced" to do that. If the legislation in the US cannot prevent overworking or sleep deprevation, that legislation must be fixed, too. Here in Finland, some professionals are arguing that the legislation is too strict and they feel that they could do longer workdays but the legislation doesn't allow that. I guess the optimal regulation would be somewhere in between but at least the regulation here results in safety.
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  44.  @mangos2888  The question is who is going to monitor and enforce the ICAO communication and phraseology rules?
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  45. "Group of Brits misbehaved on holiday, news at eleven." Even though I think the joke was very poorly planned, the bigger problem is the security theater that was kicked into action as a result. If the bombs were truly the final objective, terrorists would just start blowing bombs in the waiting line to the security checks.
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  46.  @johannesgutsmiedl366  If electronics for the force feedback motors are implemented in totally separate circuit, it would be trivial to disconnect the force feedback system in case of problems and turning the sidestricks to passive controllers used in Airbus today. And if they can implement direct drive motors for the feedback system, it will be able to transmit higher quality details to the pilots than any mechanical linkage or hydraulic system could ever deliver.
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  47. There were lots of audio/video sync problems in this interview. I hope you improve your production workflow to avoid losing sync during the editing. Other than that, great video as usual!
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  48.  @johnnunn8688  I considered this being about speculation of "I wonder how low drag would be if we would have good enough materials to avoid any braces".
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  49. Great video as usual! I fullly agree that when official declaration is "both pilots were suitably licensed and qualified to undertake the flight" it's a blatant lie to call FO as trainee or unlicensed as portrayed in the press. Sadly, the situation is not going to get any better in future because majority of the people accept clickbaits. We would need more people stopping to use any given news site when the headlines repeatedly do not match the content or news sites are going to continue this forever to increase clicks. I'd hope I'm wrong here.
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  50. 14:20 Were the pilots ever told about the Ms vs Miss issue and system incorrectly computing females as children as a result? I would assume no, because otherwise the pilots would have probably guessed that there were not suddenly much more children in the cabin than expected.
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