I have been told by more than one person over the years that when a commercial airliner is on final approach, it is inadvertently dumping/spilling/venting fuel. They say this like it is an unavoidable design flaw in jet aircraft. One fellow asked me, “haven’t you ever noticed that the fields in front of runways are always full of dead grass?” I’ve never noticed this! Another friend mentioned to me once that since our office building is in the flight path of landing planes, he has to wash his car more frequently to get the jet fuel off of his car and that we really need to have our office building power washed to get the fuel off of that too. I just can’t imagine that the EPA would allow raw fuel to be dumped from planes and I can’t imagine the airline companies would put up with their expensive jet fuel being jettisoned on every landing. Perhaps I am just unobservant but I call “[censored]” on this but I’m willing to change my opinion if confronted with facts! BTW, I’m not talking about emergency landings but rather routine commercial jet landings.
Commerical jets dump fuel on landing?
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Everything I read says only in emergencies:
http://www.answerbag.com/question_commercial-aviation-commercial-jet-airplanes-dump-fuel_511548/
John
http://www.answerbag.com/question_commercial-aviation-commercial-jet-airplanes-dump-fuel_511548/
John
On routine flights, planes may have to get rid of excess fuel so that they are lighter when they hit the ground. They do this by flying in a holding pattern for a while AFAIK. I've never heard of a plane actually dumping fuel, although I can imagine that the option exists in an extreme emergency.
You are right, that would never get past the EPA, or FAA for that matter. Jet fuel is nasty stuff. The whole city would smell like jet fuel if this happened routinely. People would be going to hospitals.
Airline companies are very peticular with their fuel usage. They would never allow fuel to be wasted like that. Airliners only carry enough fuel to get where they are going, plus a 20-30 minute reserve. A little more if the weather is bad at their destination.
Now during an emergency, if they need to land right away and still have a lot of fuel left, then yes they would dump the extra fuel in order to decrease the fire potential as much as possible. It also helps the plane to land slower, and stop faster once they are on the runway. They would try very hard to dump the fuel in a non-populated area.
Airline companies are very peticular with their fuel usage. They would never allow fuel to be wasted like that. Airliners only carry enough fuel to get where they are going, plus a 20-30 minute reserve. A little more if the weather is bad at their destination.
Now during an emergency, if they need to land right away and still have a lot of fuel left, then yes they would dump the extra fuel in order to decrease the fire potential as much as possible. It also helps the plane to land slower, and stop faster once they are on the runway. They would try very hard to dump the fuel in a non-populated area.
Jetliners don't dump or vent fuel except in emergency situations. Jet fuel is too expensive a resource for today's cash-strapped airlines (who are struggling to make a profit) to waste in that manner. A flight that is on instrument flight rules (IFR - which means the pilot is flying using flight instruments rather than visually), and this would include most airline flights, have to have an alternate airport to go to in case it can't land at the intended airport. According to the Federal Aviation Regulations, an IFR flight has to have enough fuel to go to the intended airport, fly to the alternate airport, AND fly for an additional 45 minutes after that before landing. This is how airlines calculate the fuel load they carry on the airplane, and they carry very little extra. They basically don't legally have the fuel to vent unless they're in an emergency situation!
Nope!!!
Good. You guys are making me feel vindicated! Just to let you know how widespread this belief seems to be, a guy told me just last week that the wing votices you see on planes landing in humid weather was actually fuel. He told me it evaporated before hitting the ground though. Uh....huh.
Yup, those wing vortex vapors are due to pressure gradients at the wing tips in conditions of high humidity. No fuel venting going on there. You might have also seen pictures of vapor around fighter aircraft that are traveling at or above the speed of sound.
Also, near airports there is a lot of residue from burned jet fuel that can collect on cars and surfaces near the runway. This is not jet fuel itself, but particulate from burned fuel, which is basically kerosene. Modern jet engines put out a lot less of this stuff than they used to, but it still happens. Sometimes you can smell it if the wind is blowing in the right (or wrong!) direction.
I've not noticed much dead grass near our airport but it is possible due to burned jet fuel particulates and the hot jet exhaust. That would be due more to aircraft taking off, when they are running the engines at full power, rather than planes landing. And since aircraft take off of a runway in both directions (depending on which way the wind is blowing), one would expect to see the effect on both ends of the runway.
Also, near airports there is a lot of residue from burned jet fuel that can collect on cars and surfaces near the runway. This is not jet fuel itself, but particulate from burned fuel, which is basically kerosene. Modern jet engines put out a lot less of this stuff than they used to, but it still happens. Sometimes you can smell it if the wind is blowing in the right (or wrong!) direction.
I've not noticed much dead grass near our airport but it is possible due to burned jet fuel particulates and the hot jet exhaust. That would be due more to aircraft taking off, when they are running the engines at full power, rather than planes landing. And since aircraft take off of a runway in both directions (depending on which way the wind is blowing), one would expect to see the effect on both ends of the runway.
Originally Posted By: John_K
Everything I read says only in emergencies:
http://www.answerbag.com/question_commercial-aviation-commercial-jet-airplanes-dump-fuel_511548/
John
Answerbag? Every bit as reliable as yourtube.
Everything I read says only in emergencies:
http://www.answerbag.com/question_commercial-aviation-commercial-jet-airplanes-dump-fuel_511548/
John
Answerbag? Every bit as reliable as yourtube.
Not only do airliners not dump fuel, except in emergencies, only aircraft with enough useful load for really long flights even have fuel dump capability.
Far from dumping fuel, airlines often actually tanker it.
It costs fuel to carry extra fuel for a given flight, so based upon the price of fuel at the departure airport vs the cost of fuel at the arrival airport, as well as pax load, temperature and runway length available at the departure airport, the airline may load considerably more fuel than required for the flight at the departure airport, to eliminate or reduce the amount of fuel purchased at the arrival airport for the next trip.
Another interesting point for non-pilots is that full potential engine output is not normally used in jet transports.
Rather, based upon what the aircraft weighs for a given departure, the amount of runway available, as well as ambient temperature, some fraction of the thermodynamic capability of the engines will be used in the takeoff run.
This saves a tiny bit of fuel, while greatly reducing per hour engine maintenance costs.
Far from dumping fuel, airlines often actually tanker it.
It costs fuel to carry extra fuel for a given flight, so based upon the price of fuel at the departure airport vs the cost of fuel at the arrival airport, as well as pax load, temperature and runway length available at the departure airport, the airline may load considerably more fuel than required for the flight at the departure airport, to eliminate or reduce the amount of fuel purchased at the arrival airport for the next trip.
Another interesting point for non-pilots is that full potential engine output is not normally used in jet transports.
Rather, based upon what the aircraft weighs for a given departure, the amount of runway available, as well as ambient temperature, some fraction of the thermodynamic capability of the engines will be used in the takeoff run.
This saves a tiny bit of fuel, while greatly reducing per hour engine maintenance costs.
Interesting. Did not know that about the airlines tankering fuel for return trips. Makes sense though, being how picky they are about fuel.
Im no pilot but aircrew in the military. We calculate max thrust for the day and apply a 10% thrust reduction for every takeoff. This is the rule rather than the exception. The only exception would be, a hot summer day and we are heavier than normal. Then maybe we use a 5% thrust reduction. Only one time I have seen max thrust used for takeoff and that was because we were on a short runway away from home. Throttles came back as soon as we were airborne.
The military couldn't care less about saving fuel; we do this purely to reduce wear and maintenance on the engines.
Im no pilot but aircrew in the military. We calculate max thrust for the day and apply a 10% thrust reduction for every takeoff. This is the rule rather than the exception. The only exception would be, a hot summer day and we are heavier than normal. Then maybe we use a 5% thrust reduction. Only one time I have seen max thrust used for takeoff and that was because we were on a short runway away from home. Throttles came back as soon as we were airborne.
The military couldn't care less about saving fuel; we do this purely to reduce wear and maintenance on the engines.
Originally Posted By: stranger706
Airliners only carry enough fuel to get where they are going, plus a 20-30 minute reserve. A little more if the weather is bad at their destination.
Enough fuel to fly to their destination then to the alternate plus 45 minutes, actually.
Airliners only carry enough fuel to get where they are going, plus a 20-30 minute reserve. A little more if the weather is bad at their destination.
Enough fuel to fly to their destination then to the alternate plus 45 minutes, actually.
Originally Posted By: sparkplug
Originally Posted By: stranger706
Airliners only carry enough fuel to get where they are going, plus a 20-30 minute reserve. A little more if the weather is bad at their destination.
Enough fuel to fly to their destination then to the alternate plus 45 minutes, actually.
Plus contingency fuel (not required) but i have never operate a flight without it. It's for longer taxi than expected, holding, reroute. etc.
Here's the breakdown (ignor the red circle) on top of the pic.
Originally Posted By: stranger706
Airliners only carry enough fuel to get where they are going, plus a 20-30 minute reserve. A little more if the weather is bad at their destination.
Enough fuel to fly to their destination then to the alternate plus 45 minutes, actually.
Plus contingency fuel (not required) but i have never operate a flight without it. It's for longer taxi than expected, holding, reroute. etc.
Here's the breakdown (ignor the red circle) on top of the pic.
Contingency fuel is always a good thing!! Morning departures from KPHL almost always require it.
I lived near JFK when I was growing up. We were in the final apporach of Runway 22 Left IIRC. They would dump fuel many times. You could see it floating in swimming pools and the houses that had gray roof shingles were badly discolored from it. Seems people and their health didn't mean much because not all of those landings were emergency landings.
Originally Posted By: zulu
Originally Posted By: sparkplug
Contingency fuel is always a good thing!! Morning departures from KPHL almost always require it.
Don't forget my favorite (and yours too probably): THUNDERSTORMS
How how could I forget!! I love those!! But really seeing lightening while airborne (a good distance away!) is just awesome.
Originally Posted By: sparkplug
Contingency fuel is always a good thing!! Morning departures from KPHL almost always require it.
Don't forget my favorite (and yours too probably): THUNDERSTORMS
How how could I forget!! I love those!! But really seeing lightening while airborne (a good distance away!) is just awesome.
Originally Posted By: demarpaint
I lived near JFK when I was growing up. We were in the final apporach of Runway 22 Left IIRC. They would dump fuel many times. You could see it floating in swimming pools and the houses that had gray roof shingles were badly discolored from it. Seems people and their health didn't mean much because not all of those landings were emergency landings.
Trust me, they were not "dumping" fuel so much as they were literally spitting it out the back of their terribly in-efficient low bypass turbojets. In the age of 707s, 727s, DC-9s, and early 737s, their engines were HORRIBLE at low altitudes. Actual fuel dumping occurs in the upper teens to low 20 thousands of feet unless the aircraft is an emergency upon departure still stuck in TRACON airspace. Even then, they only dump over VERY rural areas. I have never worked a fuel dump that wasn't an emergency, FWIW.
I lived near JFK when I was growing up. We were in the final apporach of Runway 22 Left IIRC. They would dump fuel many times. You could see it floating in swimming pools and the houses that had gray roof shingles were badly discolored from it. Seems people and their health didn't mean much because not all of those landings were emergency landings.
Trust me, they were not "dumping" fuel so much as they were literally spitting it out the back of their terribly in-efficient low bypass turbojets. In the age of 707s, 727s, DC-9s, and early 737s, their engines were HORRIBLE at low altitudes. Actual fuel dumping occurs in the upper teens to low 20 thousands of feet unless the aircraft is an emergency upon departure still stuck in TRACON airspace. Even then, they only dump over VERY rural areas. I have never worked a fuel dump that wasn't an emergency, FWIW.
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Kestas
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If true, this would be incredibly insolent in light of Nippon Airways' requirement to have passengers "lighten their load" at the bathroom before flying.
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