How much of the range of an airplane is used for a flight?
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How much of the range of an airplane is used for a flight?
Hi, I am an aviation enthusiast. I am very curious about this.
So the 777-200 has a listed range of 9,700 km (See Wiki for 777 pls)
Suppose air distance between city A and city B is 9510 km. Would airlines fly this distance?
I.e. My question is, what is the maximum percentage of a range of an aircraft used by a flight?
So, for example if the air distance from city C to city D is 9690 km will it be allowed to fly from C to D
with only 10 km left of the full range??
How are these things decided??
So the 777-200 has a listed range of 9,700 km (See Wiki for 777 pls)
Suppose air distance between city A and city B is 9510 km. Would airlines fly this distance?
I.e. My question is, what is the maximum percentage of a range of an aircraft used by a flight?
So, for example if the air distance from city C to city D is 9690 km will it be allowed to fly from C to D
with only 10 km left of the full range??
How are these things decided??
No simple answer and I'm not a pilot, but here goes:.
You must have sufficient fuel including reserves (contingency, holding, alternate, enough for a go around etc). these have been discussed elsewhere. You can sometimes push this a bit by en route reclearance - if you are flying from Hong Kong to London you might initially clear to Copenhagen and if you have not used your contingency fuel (typically 3% but that's an oversimplification) to reclear to London.
Ultimately the limit will be the capacity of the fuel tanks. However, that might not leave much payload (possibly only 30,000 in or 135 pax for the 747SP.
Its even more complicated as an aircraft burns less fuel when lighter so you can go further still if you take off at less than the maximum weight.
Also remember that figures stated are for still air. Have a look at the differences between flight times in each direction on FlightRadar24 and you will see the difference. Add in seasonal and day to day differences and you will see that you need a greater range than the great circle distance. Qantas had to offload a lot of passengers on the Perth - London route when faced with abnormal winds..
I saw an aircraft manufacturer (I can't remember if it was A or B) say that they were offering an aircraft with 8,000 nautical miles range but only expected it to be used on 6,000 nm routes to allow for large amounts of freight. A 777 300ER (77W) can accommodate 25 tonnes of cargo in the belly - but not between New York & Hong Kong.
A detailed discussion and charts are are available on the web. https://bigsynthesis.com/understandi...-range-diagram
The longest distance flight at the moment is Newark - Singapore (15,324 km). According to FR24 the flight on 7 August, a particularly long flight was airborne for 18 hrs 30 mins.
Now for some figures: I was recently reading an M.Sc. thesis on flying from Sydney to London non stop using a 777 200LR. The trip in the winter would take 21 hr 30 min but would require 23 hr 33 min. That looks rather high to me if you allow for reclearing en route but gives an allowance for exceptional headwinds. The weights (based on Jeppeson data) are:
Operating weight empty 144,846 kg
Fuel 145,559 kg
Payload 7,326 kg
Take off weight 297,732 kg
Fuel can be subdivided:
Trip fuel 21 hr 30 - 134,649 kg
Alternate 0 hr 14 - 1,614 kg
Hold....... 0 hr 30 - 2,565 kg
Reserves. 1 hr 19 - 6,761 kg
Total...... 23 hr 33 - 145,559 kg
Apologies - I've not sorted out how the tabbing works
However this is limited by tank capacity. You can add up to three auxilary tanks with an additional capacity of 17,095 kg which is still below the maximum take off weight (347,800 kg). Assuming that half in burnt the payload increases to around 16,000 kg or around 160 souls (say 140 pax). The flight wouldn't take longer but would burn an additional 400 kg / hr owing to the higher weight of the a/c. This would allow a full payload in an all business class configuration.
As I said, I'm neither a pilot or a despatcher and do not have access to flight planning software. Can anyone out there add to this?
You must have sufficient fuel including reserves (contingency, holding, alternate, enough for a go around etc). these have been discussed elsewhere. You can sometimes push this a bit by en route reclearance - if you are flying from Hong Kong to London you might initially clear to Copenhagen and if you have not used your contingency fuel (typically 3% but that's an oversimplification) to reclear to London.
Ultimately the limit will be the capacity of the fuel tanks. However, that might not leave much payload (possibly only 30,000 in or 135 pax for the 747SP.
Its even more complicated as an aircraft burns less fuel when lighter so you can go further still if you take off at less than the maximum weight.
Also remember that figures stated are for still air. Have a look at the differences between flight times in each direction on FlightRadar24 and you will see the difference. Add in seasonal and day to day differences and you will see that you need a greater range than the great circle distance. Qantas had to offload a lot of passengers on the Perth - London route when faced with abnormal winds..
I saw an aircraft manufacturer (I can't remember if it was A or B) say that they were offering an aircraft with 8,000 nautical miles range but only expected it to be used on 6,000 nm routes to allow for large amounts of freight. A 777 300ER (77W) can accommodate 25 tonnes of cargo in the belly - but not between New York & Hong Kong.
A detailed discussion and charts are are available on the web. https://bigsynthesis.com/understandi...-range-diagram
The longest distance flight at the moment is Newark - Singapore (15,324 km). According to FR24 the flight on 7 August, a particularly long flight was airborne for 18 hrs 30 mins.
Now for some figures: I was recently reading an M.Sc. thesis on flying from Sydney to London non stop using a 777 200LR. The trip in the winter would take 21 hr 30 min but would require 23 hr 33 min. That looks rather high to me if you allow for reclearing en route but gives an allowance for exceptional headwinds. The weights (based on Jeppeson data) are:
Operating weight empty 144,846 kg
Fuel 145,559 kg
Payload 7,326 kg
Take off weight 297,732 kg
Fuel can be subdivided:
Trip fuel 21 hr 30 - 134,649 kg
Alternate 0 hr 14 - 1,614 kg
Hold....... 0 hr 30 - 2,565 kg
Reserves. 1 hr 19 - 6,761 kg
Total...... 23 hr 33 - 145,559 kg
Apologies - I've not sorted out how the tabbing works
However this is limited by tank capacity. You can add up to three auxilary tanks with an additional capacity of 17,095 kg which is still below the maximum take off weight (347,800 kg). Assuming that half in burnt the payload increases to around 16,000 kg or around 160 souls (say 140 pax). The flight wouldn't take longer but would burn an additional 400 kg / hr owing to the higher weight of the a/c. This would allow a full payload in an all business class configuration.
As I said, I'm neither a pilot or a despatcher and do not have access to flight planning software. Can anyone out there add to this?
Last edited by Peter47; 30th Aug 2019 at 16:47.
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Hi, I am an aviation enthusiast. I am very curious about this.
So the 777-200 has a listed range of 9,700 km (See Wiki for 777 pls)
Suppose air distance between city A and city B is 9510 km. Would airlines fly this distance?
I.e. My question is, what is the maximum percentage of a range of an aircraft used by a flight?
So, for example if the air distance from city C to city D is 9690 km will it be allowed to fly from C to D
with only 10 km left of the full range??
How are these things decided??
So the 777-200 has a listed range of 9,700 km (See Wiki for 777 pls)
Suppose air distance between city A and city B is 9510 km. Would airlines fly this distance?
I.e. My question is, what is the maximum percentage of a range of an aircraft used by a flight?
So, for example if the air distance from city C to city D is 9690 km will it be allowed to fly from C to D
with only 10 km left of the full range??
How are these things decided??
Put simply, you MUST arrive at your destination with enough fuel for:
A. An approach, go-around, cruise and descent to the alternate airport; and
B. Arrive at the alternate airport with 30 minutes holding fuel.
In addition, you SHOULD arrive at your destination with enough fuel (extra to A and B) to enable some holding at destination before having to decide whether or not to divert. That extra fuel will depend on weather, NOTAMS, pilot experience of the destination, company statistics, etc.
To estimate some actual figures:
A. Obviously will vary with the distance from the destination to the alternate, but for a “Large Twin”, in a “non-remote” location, assume about 6 tonnes.
B. Depends on type and weight at the alternate but assume 3 tonnes.
C. Most crew would want 15-20 minutes extra time, especially after a very long flight, so allow an extra 2 tonnes for that.
D. Then there is the fuel consumed during start-up and taxi (0.5 tonnes).
E. In addition, there is the contingency fuel, the amount of which depends on the approvals and SOPs held by the operator, and the extra fuel which may be required due to ETOPS. Let’s assume 3 tonnes for this.
F. Finally, all of this “extra” fuel will increase the weight (mass) of the aircraft, which will further increase the fuel burn. On a super-long flight, we might burn an extra 1.5 tonnes, just to carry our additional “extras”.
So, in summation, the fuel we must deduct from the total carrying capacity, in order to calculate a figure that we can use just for the flight from departure to destination is:
A. 6.0
B. 3.0
C. 2.0
D. 0.5
E. 3.0
F. 1.5
Total 16 tonnes.
So for a total capacity of 145.5 tonnes, you could use 129.5 from departure to destination. Assume an average burn of 7.5 tonnes per hour and an average groundspeed of 480 kts gives a flight time of 17hrs 15mins and a range of 8,288 nms.
The actual fuel remaining in tanks on arrival at the destination will depend on how much (if any) contingency fuel has been used. If you’ve used the ETOPS fuel, it means you’ve diverted en-route and so this fuel should still be available to you at the end of a normal flight. The only fuel that you will definitely have used will be D and F so you might arrive at destination with as much as 14 tonnes.
A. An approach, go-around, cruise and descent to the alternate airport; and
B. Arrive at the alternate airport with 30 minutes holding fuel.
In addition, you SHOULD arrive at your destination with enough fuel (extra to A and B) to enable some holding at destination before having to decide whether or not to divert. That extra fuel will depend on weather, NOTAMS, pilot experience of the destination, company statistics, etc.
To estimate some actual figures:
A. Obviously will vary with the distance from the destination to the alternate, but for a “Large Twin”, in a “non-remote” location, assume about 6 tonnes.
B. Depends on type and weight at the alternate but assume 3 tonnes.
C. Most crew would want 15-20 minutes extra time, especially after a very long flight, so allow an extra 2 tonnes for that.
D. Then there is the fuel consumed during start-up and taxi (0.5 tonnes).
E. In addition, there is the contingency fuel, the amount of which depends on the approvals and SOPs held by the operator, and the extra fuel which may be required due to ETOPS. Let’s assume 3 tonnes for this.
F. Finally, all of this “extra” fuel will increase the weight (mass) of the aircraft, which will further increase the fuel burn. On a super-long flight, we might burn an extra 1.5 tonnes, just to carry our additional “extras”.
So, in summation, the fuel we must deduct from the total carrying capacity, in order to calculate a figure that we can use just for the flight from departure to destination is:
A. 6.0
B. 3.0
C. 2.0
D. 0.5
E. 3.0
F. 1.5
Total 16 tonnes.
So for a total capacity of 145.5 tonnes, you could use 129.5 from departure to destination. Assume an average burn of 7.5 tonnes per hour and an average groundspeed of 480 kts gives a flight time of 17hrs 15mins and a range of 8,288 nms.
The actual fuel remaining in tanks on arrival at the destination will depend on how much (if any) contingency fuel has been used. If you’ve used the ETOPS fuel, it means you’ve diverted en-route and so this fuel should still be available to you at the end of a normal flight. The only fuel that you will definitely have used will be D and F so you might arrive at destination with as much as 14 tonnes.
If it helps, the range figures quoted by manufacturers typically list a set of assumptions, for example those Wikipedia Boeing figures assume:
Standard day, zero wind [as referenced by previous posters]
0.84 Mach step cruise
Typical mission rules [i.e. reserves]
Normal power extraction and air conditioning bleed
Specified seating configuration
Standard day, zero wind [as referenced by previous posters]
0.84 Mach step cruise
Typical mission rules [i.e. reserves]
Normal power extraction and air conditioning bleed
Specified seating configuration
So for a total capacity of 145.5 tonnes, you could use 129.5 from departure to destination. Assume an average burn of 7.5 tonnes per hour and an average groundspeed of 480 kts gives a flight time of 17hrs 15mins and a range of 8,288 nms.
If the total fuel capacity is 145.5 tonnes, then using the same assumptions, the time from take-off to flame-out would be
145/7.5 = 19hrs and 20mins.
The distance travelled would be 9,280 nms.
Both of these values show that in my previous example, the aircraft used 89% of its ultimate range and endurance.
