 What are the three reasons, you just tell one reason, that is never a reason, if there is a leak then nothing will stay, the fuel also will go, the fuel will not remain, the fuel if there is a leak, so you never fly if there is a leak. So either you have to keep flying at a particular height which is called as a hold because the runway is not free for some time or you may have to divert to an airport nearby because the runway is not accessible, so reserve fuel, one of the reasons for reserve fuel is diversion and holding, so in the next lecture on takeoff and landing we will cover this in slightly more detail, that is one reason, any other reason, yes, so therefore, so you have a very low view about aircraft maintenance engineers and pilots, somebody thinks that the fuel can leak, somebody can think that the instruments are not working, if this is the case the aircraft will not be clear to operate and reserve fuel will not help because then you do not know how much fuel you have, so I am sorry to say that your opinion about us is very bad, we are not so, in fact, we are far more systematic than this, yes any other reason? There will be, there will drastically change and we need the drag wind increase, how does drag increase because of weather, does the drag increase, okay, fine, so if the wind increases now we will see today that if you have tail wind actually it is beneficial, it is only if there is a head wind that the range will be less, so I understand what you can say is that on route weather conditions may become bad, so you may have to divert, okay, I was travelling once from Calcutta to Mumbai and the pilot said that we are diverting because there is heavy weather over Ranchi, so they took a circuitous path not the path which is normally taken, so that added 15-20 minutes to the flight, so we need fuel for that, so that is right, one reason is that you need fuel for weather diversions, you need fuel for at the end of the journey you may have to hold or divert any other reason, there is one more reason, other than this, there could be navigation errors, that means you think you are going on that route which the ATC has given you but actually when you come to know you are slightly off so you come back, this is a part of, so end route weather and navigation and holding and diversion, any other reason, there is one more reason, so those of you who have a vehicle with you, are you able to use the entire fuel in the fuel tank or there is some fuel that is not available, so there is some fuel always trapped in the pipelines, you will be surprised to know that this fuel can be almost half percent of the fuels of life, so the power plant is mounted on the wings and the fuel tanks are also in the wings, there is a piping, in some cases the fuel tank is in the wing but the power plants are on the back, there is a pipeline which carries the fuel and we do not keep flying or we do not plan to fly till the pipeline fuel also is consumed, because we want to maintain a continuous supply of fuel in the engines, so there is some amount of fuel which is kept, so it is unavailable fuel, it is there but not useful to you for your consumption because it is blocked in the pipelines, so these are the three main reasons due to which we do not fly like this up to empty, so total distance on a given tank of fuel is defined as range, so let us look at the range of some typical aircraft which we are familiar and this particular series of pictures tell you the range of some standard aircraft from Mumbai, so if you travel on Airbus A318 you can cover literally up to Libya and Chad on this side and you can meet Kim Jong-il if you are interested, you can go up to Korea, okay, so this is Airbus 318, 319 goes slightly further but less number of passengers, so it can cover but you cannot go to Norway, 320 is less than 321 because they are designed for a different market, I will show you the range and capacity very soon, this is 321, you can see it starts touching Australia now and this is Airbus A380, this information was given by the Airbus people when they came and gave a talk, so I have borrowed the slide from them, so you can see that almost every part of Africa, Europe, Asia, Australia, New Zealand, all that is covered including North America, what is not covered is Chile, Paraguay in South Africa that is out of the range and also Mexico, so these yes, any other, yeah so basically what it means is that the area on the right of this line and the left of this line is not covered, so Sao Paulo is covered, Rio is covered because that comes in Brazil which comes somewhere here, okay, so it is not that they have designed it like this, it is just that this aircraft with 555 passengers can travel around 15,100 kilometers nonstop, so do you think it is a very big range, 15,100 kilometers nonstop, do you think it is a big range, now let me show you some numbers for really big ranges, so since I spent a year in Singapore, there I collected some data regarding Boeing 777 from Singapore where it goes, so you can see that Boeing 777-200 from Singapore can cover 9700 kilometers, okay, then we have 300 which can cover 11,400, then we have 200 extended range or ER that is 14320 and then we have 777-300 ER which is 300 extended range that is 147, of course you cannot carry the same number of passengers in all these routes, there is a diagram called as a payload range diagram which tells you the tradeoff and then you have 777-200 long range more than extended range which can cover 17,600 kilometers but even this is not the longest, okay, now for every aircraft in the Airbus table there is normally a competition in the Boeing's table, so they always fight neck to neck and they say if you want this why not take this, if you have that why not take this, so they keep on making such charts, this chart is made by Air France where they try to compare Airbus with Boeing, okay, so once the PPT is uploaded you can see this at leisure and get an idea about this, okay, let us look at the world's longest nonstop flight, this was done by Singapore Airlines as you can see the date is mentioned there the first landing of this aircraft at Newark Airport in New York EWR, it was in June 2004 and you can see that the aircraft is being welcomed by water cannon from both sides, this is a typical thing they do in aviation whenever there is any new activity a new aircraft comes they have this system of welcoming the aircraft by on both sides they fire a water cannon, okay, so this is 16,600 kilometers more than 18.5 hours nonstop and look at the phenomenal amount of fuel consumed per flight so it was launched with great fanfare by Singapore Airlines in 2004 at that time it was the world's longest flight not no longer there are longer flights than this but it held the record for good amount of years approximately 9 years in 2013 this flight was and the aircraft that they use is Airbus A34500 which is also considered to be one of the world's longest aircraft but they discontinued so do you have any idea why they discontinued this flight no idea can you guess if an airline launches with a lot of fanfare a flight which is a world record they would like to keep it isn't it because that gives them some distinction yeah so you can guess what is the reason yeah that is the reason but there is a slight slight twist to that so when they launched this flight they were flying with 181 passengers but then they realized that this is a very exclusive thing so they made it all business class okay and about 101 or 102 seats it was successful for a long time but then it became difficult to sustain to get 100 business class passengers for a flight of this distance they had to do a lot of expenditure in maintaining that finally they said give up we cannot do it but interestingly before that also the record was by another Singapore Airlines aircraft that was from Singapore to Los Angeles and that was 14 and a half odd kilometers around 16 hours but the world record for the longest flight non-stop is held by Air India okay and that is Delhi San Francisco flight which took place in 2016 now if you notice there are dates mentioned there and if you also notice on 13th October last year 2016 they flew a polar route that means they flew over the poles which normally we do not fly you can notice that the distance is only 13959 as compared to 15142 also notice that the time taken is more for the polar route 16 hours and 44 minutes as compared to the 14 hour 30 minutes for the Pacific route so the flight went around the world literally it went from Delhi to San Francisco and then back from San Francisco to Delhi so now the distance on the earth is the same or is it not the same why does it take more time more distance to go this way than that way and why does it take more time on a small on a shorter route okay so look at the numbers this is the aircraft Boeing 777 200ER which was used okay so flying westward you get what is called as a headwind that means the wind coming from the front is that desirable no it is not desirable for range it gives you better relative velocity but it gives you poor ground speed so theoretically speaking if the air speed is equal to the headwind the ground speed is zero the aircraft is stationary in there so whenever you look at some aircraft flying and if you are fly traveling on a car at a particular angle it seems stationary isn't sometimes sometimes you feel it is just right there and you keep on traveling on the route and you think it is not good or you or you see traveling very slowly okay so that is the thing so ground speed basically so when you fly eastward then you encounter the jet streams behind you so they are literally pushing you and pushing you not at a slow speed pushing you at 138 kilometers per hour that is the speed at which the air in atmosphere travels in the jet streams and this is what Google loom does they want to take their balloons in jet stream and then free of course they are traveling from distance and then they come down they are riding the wind literally so similarly the aircraft is riding the wind and you can see the ground speed is 930 kilometers per hour that is why there is a two hour reduction in flight time if you fly eastwards so that is the difference and this two hours eastward results in 13 tons saving in the fuel so you can make out how much is the benefit of traveling time is saved for the passengers so you take off at 4 a.m. and land at 6 30 a.m. on the same day because 12 hours is the time difference it is like a Delhi Mumbai Delhi flight typically you take off at 4 a.m. and land at 6 30 a.m. on the same day and this record is also going to be broken soon now I do not have any confirmation but there was a proposal that Singapore airlines again that roped airline they want to now fly 90 hours nonstop from Singapore to New York but as per the available information this flight has not yet taken place so I do not know so it is up to you now to confirm this so this is a Moodle question people are very silent on Moodle nobody is taking part of mood except for giving their comments on the examination type after the last date is over people are now very quiet on Moodle okay so please use the Moodle page tell me if there is a record broken find out and tell me if really there is any other flight which is more than this distance and more than this time okay so this is the range payload diagram which actually tells you how far an aircraft can travel with a given amount of payload the payload of an aircraft consists of passengers their baggage and cargo okay so this diagram has got a very interesting feature there is one line which is line A to B on the top you can see there is a line this A to B this line is called as the maximum payload line this line represents the distance that you can travel with maximum amount of payload with different amount of fuel so if you do not carry any fuel you have only reserve fuel and zero mission fuel then you are at point number A that means the aircraft is fully loaded there is no more capacity of carrying payload remember one thing the payload of the aircraft can be limited by either weight or by volume or by both because payload is kept in a particular area the payload carrying bay and that area has got a structural limitation if you load that area more than a particular mass it can lead to structural damage or the volume available in that payload carrying bay it could be filled up before reaching the maximum weight limit so either it is volume limited or it is payload limited so if you are carrying lead you will probably hit the weight limitation first if you are carrying cotton you will hit the volume limitation first whatever be the case there is a maximum payload you can carry in kilograms or in the weight units so any point from A to B corresponds to one particular flight in which the aircraft is filled with maximum payload and then you keep adding then you add some fuel the mission fuel and on that fuel you travel some distance now you cannot go beyond point B with full payload because at point B you have now hit the maximum takeoff weight capacity limit at point number B two things are happening the payload is maximum and the total weight is also maximum takeoff weight okay so do you think the fuel tank is full at point number B you have reached the limit of maximum takeoff weight and you have reached the limit of maximum payload carrying capacity so at point number B what is the fuel weight is it equal to the maximum fuel weight possible no that is not the case you have space in the fuel tank but you cannot carry fuel the reason is you have hit the maximum takeoff weight limit if you put more fuel then the load on the landing gear will exceed the load for which it is designed for safe operation so not permitted but let us say you want to travel further so the tradeoff is remove some payload and add that much fuel to hit the max takeoff weight limit so along line B and there should be another point here called C this point here this point could be called as point number C up to point number C from B you travel now understand one thing you are not this is not a graph that shows how you are traveling it just shows you the operational point so any flight is only a point in this diagram so there could be an operating regime in which so when you when you go from B to C so what is constant for all operating point between B to C just like for all operating point between A to B the only thing what is common between A to B the payload is maximum okay from point B to C the takeoff weight is equal to max takeoff weight so at point number B you have both the things its intersection at point number B you have payload maximum and takeoff weight maximum so that point is a very important point from the airline point of view what is the farthest we can go without compromising on payload so the range below B is called as a harmonic range harmonic range is a real measure of two aircraft if they have to compete from the capacity and payload range and payload point of view you should compare the harmonic range how much can you travel with full payload how much can you travel so if he can travel more better aircraft from the airline point of view but airlines do not travel only on one route the same aircraft is used from Mumbai to Pune and Mumbai to Delhi okay so therefore it may be required that you go beyond the maximum possible go beyond point number B so the only option for that is to trade between fuel and payload so you take out some payload add fuel till you hit maximum takeoff weight that will be from point number B to point number C okay now at this point you hit one more limit now your fuel tank is full so at this point which I will mark as C when I load this presentation the fuel tank is full so now you cannot put more fuel and obviously to travel this distance you cannot carry maximum payload you can see the payload is lower the payload value is somewhere here so from point B to point C we have the max takeoff line at point C we hit the maximum fuel limit now I want to still travel further now what is the option remove some payload but why will it travel more because the gross weight is now lower so it will consume less fuel per nautical mile hence its range will be better okay but this particular line normally it is not so prominent in many cases it is a straight line in many cases it is just a small inclination it comes somewhere here but from the point of view of description we can say there is a line so what is common along that line what is common along that line fuel tank is full so these three lines are called the limiting lines this is the max payload line this is the max takeoff weight line this is the max fuel line and the intersection points are max takeoff and max payload max takeoff and max fuel yes so in the maximum payload line from A to B is it because of the volume concerns that we cannot know it could be volume it could be weight whatever be the case I cannot carry more than so many kilograms of payload so you stuff the aircraft with payload till you hit either the maximum weight carrying capacity of the payload bay payload bay or the maximum volume carrying capacity of the payload bay more than that I cannot carry so I cannot stuff payload in the passenger cabin I cannot say each passenger will carry one more suitcase because we have to carry more payload so take some letters some courier letters please on your lap you keep a bag with some letters for courier there you cannot do that unsafe okay so this is a very important program diagram which is used by all airlines in planning so you can see now if you want to check so these are graphs for Boeing 777 under various conditions so you can see that the same aircraft 777 300 ER 777 200 ER 777 200 LR all of them they have different maximum payloads and hence they are different ranges now in this if I superimpose the aircraft of the Airbus company then you can make out which aircraft is fighting with which aircraft in the market roughly all right so let us look at world records in aircraft range we will see this very soon the world record is held by Steve Fawcett on a global flyer 41,004 around kilometers non-stop non-stop and before that many years ago Bevert Rutan designed an aircraft we will see a video of that hopefully in 1986 which traveled almost 40,000 so both of them went around the globe the first one was the voyager and the last one recently was the global flyer so but these are not passenger aircraft these are aircraft designed for these special missions so let us look at global flyer yeah Sir do we include gliders also in the range gliders can be included but see gliders are not typically for gliders you cannot classify as range this one is aircraft which has got a power plant so global flyer does it mean that at 41,000 the fuel was zero not zero they had reserve fuel remaining yeah yeah so we can fly if the fuel is also zero it can turn off and it can yeah but that is not considered see glider is not considered to be a candidate for aircraft world record so yeah technically speaking yes once the fuel runs out you can keep gliding if you are lucky you can get seven more hours eight more hours no this one is on a fuel but there is a difference so let me see let me show you the clip if the clip works so you can see the global air consists of basically three fuselages there are many aircraft that have got three engines and one fuselage this is a unique one which has three fuselages and one engine a single engine mounted on the middle here on the top the global flyer was designed and built with just one mission in mind to fly around the world without stopping and without refuelling richard branson's airline virgin was a major sponsor for the project and the plane's full name was the virgin atlantic global flyer the company had invested more than a million pounds in the record attempt at takeoff 83 percent of the plane's weight would be fuel the plane's owner and its pilot for the attempt was adventurer steve fosif he'd already been around the world in a yacht and a hot air balloon made from epoxy reinforced with carbon fiber the plane has 13 fuel tanks feeding a single jet engine to save energy the plane was not equipped with fuel heaters instead it would burn a special aviation fuel with a lower freezing temperature to further minimize fuel usage the plane would fly in an easterly direction to take advantage of the earth's prevailing winds and it would only embark after the ground team could be certain that the global flyer would have tailwinds for most of its flight to have the record recognized the plane's flight path had to be no less than the earth's circumference at the tropic which is a distance of 36,787.559 kilometers early in 2005 the global flyer completed its trans-global flight in slightly more than 67 hours the following year steve fosif set another record in his plane flying the longest ever non-stop flight of more than 41,000 kilometers the global so can you tell me why is it not going on a straight path why is it going this way then down then up then down yes what do you think so maybe two circumvent areas of bad weather and also restrictions in the airspace over something that is one that is one constriction restriction of airspace for example libya did not permit them to fly but the main reason is not only airspace the main reason is as they mentioned the route was planned to ensure that the circumference of the earth is covered at the tropics because you could cheat by going around the earth at the northern latitudes or southern latitude so they said for the world record you should cover more than the earth circumference at the tropical and secondly they always wanted to have heavy tailwind behind them so the success of global flyer is a success of weather prediction technology in equal measure so there was a ground based weather station which was predicting the wind so they were changing altitude changing direction in real time ensuring that they get the maximum support from atmosphere by a tailwind that is why they had to go for such a circuitous path so this was in 2005 and 6 okay so you can see now so there are some ultra long aircraft so there is this Boeing 7778X which has now been made into Boeing 7779 you can see the range is 17250 so many aircraft are available who can fly but the payload is the lowest it's just 350 passengers and Airbus A380 is here it can travel around 15500 and more but it can carry 555 passengers