Thanks for the video but my approach was abit diffrent. It doesnt matter how many passenger that travels, every runway has its capacity. If we assume that average take off time once the plane is on the take off runway is 3 minutes (permit from ATC, execute takeoff checklist and so on) this would mean that a runway kan manage around 20 take off/hour. this means in 24 hours total take offs would be 480 flights/terminal. Assuming that it operates on 24 hour basis. Multiple that by the approximate amount of terminal lets say 5 terminals, total flight would be around 2400flights/day plus minus 10-20% depending on how busy they are. This is actually a reasonable nr considering Arlanda in stockholm has capacity of around 1800flights a day. This is just an assumption based on minimal knowledge of delhi airport. I just refered to other airport such as schipol etc. If you have knowledge regarding delhi airport beforehand then this would make it lot more easier. You find what nr make sense and what dont. Another approach is by looking at how many gates they have. Assume that all 5 terminals averaging around 40gates. Try to find out the gate capacity. Lets assume that on average plane switches every 2/hours. This means that on 24 hours basis a gate can manage up to 12 planes. Now multiply amount of plane x gates x terminals. So 12 x 40 x 5= 2400flights a day Again plus minus10-20%
Nice approach and a very clear cut explanation. But just one thing I would like to mention, Delhi airport (IGI) has 3 terminals. 2 domestic terminals + 1 International terminal So the final answer according to me can be = 360+360 that is 720
I think we should also take into account the time taken by flights that would land and in that time the flights can't fly out for any particular runway
I took different timings - Busy, medium busy, Not so busy... Busy - 5flights/hr Medium - 4 flights/hr Low - 2f/hr After considering different timings my ans is - 80 flights/day Total ans after 2 take off runways - 160 Is it right?
@@goddessvibes08 Interviewer checks the approch. He/She really dosen't care about the answer. Though if you get close to the answer that means your assumption are right on point
Lets say , My way is to calculate top 4 metropolitan states of India from Delhi : Mumbai , Kolkata , Gujrat , and Bangalore , Assuming that the flights to these states depart in every hour from Delhi airport we get to number 24×4 flights = 96 flights , since there are 29 -4 states left =25 states these 25 states we assume (1/3) Flights come in frequency of 1 in three hours or so because it doesn't get filled very easily , then 24/3 almost ~ 8 or say 9 flights ,. Considering the weather is not bad and flights are not cancelled we get 96 + 8*25 = 296 domestic flights at this point I would ask the interviewer if to continue the same for Internationals flights .. i would pick top 12 world location on the baisis of my whim ( in my mind Its a movie dialogue from 11 muluko ki police hume dhundh rhi h) So those 11 countries i would try with same hour logic but since its international flights time delay is there and many ambiguity so every 3 hours per an international flight , That reaches us to 8 flights for one country , so for 11 countries = 88 flights in one day for 1 metro politian city , For 4 metro politian cities. 4*88 = 352 . For convenience let's say ~100 flights ( which is including non popular (countries) ) My final answer would be 352 + 296 = 648 flights Domestic + international flights ! On a typical Day in Delhi
The operation of runways depend on the winds direction and some other factors.. As we have taken the bottle neck to be no. of runways in operation.. considering a factor for usability of particular runway might get a better solution.
Ok, I though a bit differently. I divided the number of flights into domestic and international. For the domestic, I again divided it into metro cities and non metro cities. I considered 7 metro cities, Mumbai,Bangalore,Chennai,Kolkata,Ahmedabad and Pune. I assumed that one flight is there every hour. Hence for metro cities, number of flights = 24*7=168. I assumed 25 non metro cities and the frequency of flight as 1 flight per 3 hours. Hence total=25*8=200. Assuming 10 percent of these are break flights, meaning they will go via a metro city, total = 180 flights. Hence, total domestic flights = 380. I have no idea for number of international flights, so I assumed 50% of the total domestic flights from delhi will be equal to international. Therefore, total=0.5*380=190. This includes both direct flights from Delhi to a country as well as the flights which may have a hault at delhi and will go to a different country post hault. Hence total=570 flights. Now , since this method considered a vague assumption on the international departures,a SANITY CHECK can be done to check whether the final answer is possible or not. For that we can use the method of the video which counts the maximum flight that can take off from delhi in a day. If the numbers are at a little margin, then the assumptions are correct.
I think his approach is a little cumbersome. I have an alternate approach. Instead of looking at runways, why don't we look at the number of terminals. So, here's a simple formula: Z(No. of flights taking off from Delhi in a day) = X(# of Terminals) x Y(Frequency of usage: assuming it takes about 3 hours for a flight to arrive, dock, ready up & take off & an 18 hour operating window: the frequency will be about 6. Let's round of to 5). so, my answer is Z = 50 x 5 = 250.
I agree with you, my approach was kinda of the same. It doesnt matter how many passenger that travels, every runway has its capacity. If we assume that it takes around 3 minute for a plane to take of(permit from ATC, execute takeoff checklist and so on) this would mean that a runway kan manage around 20 take off/hour. this means in 24 hours total take offs would be 480 flights. Multiple that by the approximate amount of terminal lets say 5 terminals, total flight would be around 2400flights/day plus minus 100 to 200 depending on how busy they are. This is actually a reasonable nr considering Arlanda in stockholm has capacity of around 1800flights a day. Another approach is by looking at how many gates they have. Assume that all 5 terminals averaging around 40gates. Try to find out the gate capacity. Lets assume that on average plane switches every 2/hours. This means that on 24 hours basis a gate can manage up to 12 planes. Now multiply amount of plane x gates x terminals. So 12 x 40 x 5= 2400flights a day Again plus minus 100-200.
Vehicles ,cars Traffic peak hours on roads due to office timings is understandable but how to justify peak hours of operation for an airport? What could be driving factor for airport peak hours? Like eg. For road traffic it's office timings
What if I am not aware of all the type of airports Delhi has? Do I just proceed considering just the passenger flights or ask the interviewer about the types of flights he is expecting to be taken under consideration?
Hello Sir. Seen your guess estimate video. Can you please guide me for a guess estimate activity for total number of professional cricket players in India.
how do u assume that in the peak frequency , a landing/takeoff happens every 2 minutes? assume the airport is Ranchi or Jaipur. The peak hour would still be same, but we cannot assume the landing/takeoff to happen every 2 minutes
that is the meaning of an assumption it is an assumption I think he repeated this twice in the video, you don't need to make accurate assumptions. The assumptions are relevant to show that you have thought about these factors.
See taking it the peak time you take 180 flights leaving that means around 30 flights /hour that means 2minutes for each flight. Do you really think the loading and unloading procedure will take just 2 minutes time?
Hi Aditya, Good content!! Please could you explain why did you multiply 360 by 1.5 to take flights from other runway in to account? Factor 1.5 didn't make sense to me.
I feel like there should be a runaway for each direction in Delhi, so multilplied factor should be 6. Only then will the answer reach the closest guess to real numbers in Delhi, which is 900-1000
Assuming it's a winter holiday, Delhi's population to 20 million, out of which 1 million fly in year, but it is holiday and dividing days with passengers, supposedly there are 60 days of holiday (including sundays and Saturdays) 60000 fly in holidays, 1000 fly this day, other 200 that day.. total of 1200 fly this day Assuming every plane has 40 seats, we can say that total of 30 planes are required for that day assuming all planes have same seats and same seats economies. There are 2 airports in delhi, we can multiply this by 2 and get answer 60 flights that day
Hey check the video around 6 min 30 sec mark- I mention that there are a total of 1.5 runways involved. So my calculation for one runway is multiplied by addition 0.5, i.e. multiplied by a total factor of 1.5. I hope this clarifies it :)
![[19/30] Guesstimate: Estimate the number of users of Rajiv Chowk metro station in a day](/img/n.gif)
Thanks for the video but my approach was abit diffrent. It doesnt matter how many passenger that travels, every runway has its capacity. If we assume that average take off time once the plane is on the take off runway is 3 minutes (permit from ATC, execute takeoff checklist and so on) this would mean that a runway kan manage around 20 take off/hour. this means in 24 hours total take offs would be 480 flights/terminal. Assuming that it operates on 24 hour basis.
Multiple that by the approximate amount of terminal lets say 5 terminals, total flight would be around 2400flights/day plus minus 10-20% depending on how busy they are. This is actually a reasonable nr considering Arlanda in stockholm has capacity of around 1800flights a day.
This is just an assumption based on minimal knowledge of delhi airport. I just refered to other airport such as schipol etc. If you have knowledge regarding delhi airport beforehand then this would make it lot more easier. You find what nr make sense and what dont.
Another approach is by looking at how many gates they have.
Assume that all 5 terminals averaging around 40gates. Try to find out the gate capacity. Lets assume that on average plane switches every 2/hours. This means that on 24 hours basis a gate can manage up to 12 planes.
Now multiply amount of plane x gates x terminals.
So 12 x 40 x 5= 2400flights a day
Again plus minus10-20%
I thought the same , but you have to divide by 2 because you didn't count arrivals .
@@dedman8884 question says 'out of delhi'
Your method is actually far better and easier and gives a much closer answer.
IGI is infact in Delhi actually, not gurgaon. Nice approach though, thanks for the video!
Very helpful, one of the simplest approaches I have seen.
dude, atleast make some flowchat to show this.
Very well explained but the only issue is the sound is too low.
Nice approach and a very clear cut explanation.
But just one thing I would like to mention, Delhi airport (IGI) has 3 terminals.
2 domestic terminals + 1 International terminal
So the final answer according to me can be = 360+360 that is 720
I think we should also take into account the time taken by flights that would land and in that time the flights can't fly out for any particular runway
We have considered different runways for dept and arrival
You could've included the number of terminals as well.
I took different timings - Busy, medium busy, Not so busy...
Busy - 5flights/hr
Medium - 4 flights/hr
Low - 2f/hr
After considering different timings my ans is - 80 flights/day
Total ans after 2 take off runways - 160
Is it right?
It's impossible to fly 30 flights in 1 hour . Because it takes at least 10 minutes to prepare itself to fly.
When so many assumptions are allowed in Guesstimate, why not just assume the asnwer and let ie be like all the numbers being assumed in the solution
Exactly
@@goddessvibes08 Interviewer checks the approch. He/She really dosen't care about the answer. Though if you get close to the answer that means your assumption are right on point
Approach matters way more than answer.
Lets say , My way is to calculate top 4 metropolitan states of India from Delhi : Mumbai , Kolkata , Gujrat , and Bangalore , Assuming that the flights to these states depart in every hour from Delhi airport we get to number 24×4 flights = 96 flights , since there are 29 -4 states left =25 states these 25 states we assume (1/3) Flights come in frequency of 1 in three hours or so because it doesn't get filled very easily , then 24/3 almost ~ 8 or say 9 flights ,. Considering the weather is not bad and flights are not cancelled we get 96 + 8*25 = 296 domestic flights at this point
I would ask the interviewer if to continue the same for Internationals flights ..
i would pick top 12 world location on the baisis of my whim ( in my mind Its a movie dialogue from 11 muluko ki police hume dhundh rhi h) So those 11 countries i would try with same hour logic but since its international flights time delay is there and many ambiguity so every 3 hours per an international flight , That reaches us to 8 flights for one country , so for 11 countries
= 88 flights in one day for 1 metro politian city , For 4 metro politian cities. 4*88 = 352 .
For convenience let's say
~100 flights ( which is including non popular (countries) )
My final answer would be
352 + 296 = 648 flights
Domestic + international flights !
On a typical Day in Delhi
A suggestion: Clarification: Should we count flights that fly twice from the same airport ?
It would not make any diffrence as the runway capacity would not change.
It will be counted as two flights
The operation of runways depend on the winds direction and some other factors.. As we have taken the bottle neck to be no. of runways in operation.. considering a factor for usability of particular runway might get a better solution.
Wow! This cleared the f*ing concept so easily!! Thaaaaaaaaaaaanks Aaditya
i came here after shweta arora recommended your channel
Ok, I though a bit differently.
I divided the number of flights into domestic and international.
For the domestic, I again divided it into metro cities and non metro cities.
I considered 7 metro cities, Mumbai,Bangalore,Chennai,Kolkata,Ahmedabad and Pune. I assumed that one flight is there every hour.
Hence for metro cities, number of flights = 24*7=168.
I assumed 25 non metro cities and the frequency of flight as 1 flight per 3 hours. Hence total=25*8=200. Assuming 10 percent of these are break flights, meaning they will go via a metro city, total = 180 flights.
Hence, total domestic flights = 380.
I have no idea for number of international flights, so I assumed 50% of the total domestic flights from delhi will be equal to international.
Therefore, total=0.5*380=190. This includes both direct flights from Delhi to a country as well as the flights which may have a hault at delhi and will go to a different country post hault.
Hence total=570 flights.
Now , since this method considered a vague assumption on the international departures,a SANITY CHECK can be done to check whether the final answer is possible or not. For that we can use the method of the video which counts the maximum flight that can take off from delhi in a day. If the numbers are at a little margin, then the assumptions are correct.
I don't think a single flight takes 2 minutes to clear the runway, approx time should be 15 minutes ...
Correct me if i am wrong
Why don't just go by Supply side, as we can see Demand Side Approach needs alot estimation ...??
I think his approach is a little cumbersome. I have an alternate approach. Instead of looking at runways, why don't we look at the number of terminals. So, here's a simple formula: Z(No. of flights taking off from Delhi in a day) = X(# of Terminals) x Y(Frequency of usage: assuming it takes about 3 hours for a flight to arrive, dock, ready up & take off & an 18 hour operating window: the frequency will be about 6. Let's round of to 5). so, my answer is Z = 50 x 5 = 250.
how do u say the capacity of terminals are the same ?
I agree with you, my approach was kinda of the same. It doesnt matter how many passenger that travels, every runway has its capacity. If we assume that it takes around 3 minute for a plane to take of(permit from ATC, execute takeoff checklist and so on) this would mean that a runway kan manage around 20 take off/hour. this means in 24 hours total take offs would be 480 flights.
Multiple that by the approximate amount of terminal lets say 5 terminals, total flight would be around 2400flights/day plus minus 100 to 200 depending on how busy they are. This is actually a reasonable nr considering Arlanda in stockholm has capacity of around 1800flights a day.
Another approach is by looking at how many gates they have.
Assume that all 5 terminals averaging around 40gates. Try to find out the gate capacity. Lets assume that on average plane switches every 2/hours. This means that on 24 hours basis a gate can manage up to 12 planes.
Now multiply amount of plane x gates x terminals.
So 12 x 40 x 5= 2400flights a day
Again plus minus 100-200.
Thank You so much Aaditya
What if we didn't know the no of runways in Delhi airport?
you make assumptions. they just want to know if you can think of these kinds of factors.
Vehicles ,cars Traffic peak hours on roads due to office timings is understandable but how to justify peak hours of operation for an airport? What could be driving factor for airport peak hours? Like eg. For road traffic it's office timings
What if I am not aware of all the type of airports Delhi has? Do I just proceed considering just the passenger flights or ask the interviewer about the types of flights he is expecting to be taken under consideration?
Can you pls do a case on estimating the fleet size of Air India.
Is that means the same 540 flights will land also
That means we have total of around 1100 flights land and takeoffs from IGI airport??
can you give access to the private videos on this channel
Hello Sir. Seen your guess estimate video. Can you please guide me for a guess estimate activity for total number of professional cricket players in India.
how do u assume that in the peak frequency , a landing/takeoff happens every 2 minutes? assume the airport is Ranchi or Jaipur. The peak hour would still be same, but we cannot assume the landing/takeoff to happen every 2 minutes
that is the meaning of an assumption
it is an assumption
I think he repeated this twice in the video, you don't need to make accurate assumptions. The assumptions are relevant to show that you have thought about these factors.
Can anyone help me to estimate the total number of professional cricketers in India using Demand side or supply side approach. Please
See taking it the peak time you take 180 flights leaving that means around 30 flights /hour that means 2minutes for each flight. Do you really think the loading and unloading procedure will take just 2 minutes time?
Loading and unloading does not take place on the runway. He is considering the time taken to finally takeoff after being on the runway.
wdf is IGI? why using jargons
good but it will be more helpful if you explain this on paper
Hey, thanks for that advice. Have made the newer set of videos (uploaded some and others upcoming) on paper/ppt.
Exactly
Why multiply by 1.5 ? You should have multiplied by 3
Show us the calculation paper also.. and please use some better mic
Hi Aditya,
Good content!!
Please could you explain why did you multiply 360 by 1.5 to take flights from other runway in to account? Factor 1.5 didn't make sense to me.
Hey,
That is because there are 3 runways in Delhi. He explained this in the beginning.
I feel like there should be a runaway for each direction in Delhi, so multilplied factor should be 6. Only then will the answer reach the closest guess to real numbers in Delhi, which is 900-1000
Assuming it's a winter holiday, Delhi's population to 20 million, out of which 1 million fly in year, but it is holiday and dividing days with passengers, supposedly there are 60 days of holiday (including sundays and Saturdays) 60000 fly in holidays, 1000 fly this day, other 200 that day.. total of 1200 fly this day
Assuming every plane has 40 seats, we can say that total of 30 planes are required for that day assuming all planes have same seats and same seats economies. There are 2 airports in delhi, we can multiply this by 2 and get answer 60 flights that day
I live in delhi and igi airport is not in Gurgaon its in palam new Delhi it touches gurgaon border
does it really matter here?
SOUND
Good stuff! Thanks a lot
Shouldnt bottle neck be cost and not runway?
If we would have taken demand side in consideration, since here supply side we are taking runway is the best possible answer
@@shilpisinha921 but thats ill-logical at best.
why are runways bottleneck? In 10 years, if population becomes 10 times, why cant we build 10 more runways?
You are the best
I thought exactly the same before listening to the solution
Why 1.5 multiplied?
See the video from 6:30 mark u will get it
at th-cam.com/video/ILUWBewGes0/w-d-xo.htmlm28s you said 1.5 why? shouldn't it be half (i.e.0.5).
Hey check the video around 6 min 30 sec mark- I mention that there are a total of 1.5 runways involved. So my calculation for one runway is multiplied by addition 0.5, i.e. multiplied by a total factor of 1.5.
I hope this clarifies it :)
Thanks!!!!
Plz get a mic
why multiply by 1,5?