Eco Inform is a news agency. Why does a plane run out of fuel before landing? In what cases does a plane dump fuel?
Question: I've always wondered why planes making emergency landings these days don't dump fuel. Indeed, in the event of a crash, many people can survive thanks to modern safety equipment on board the aircraft, but die in the subsequent fire after the crash or suffocate from carbon smoke.
Answer: You think that pilots know that a crash is inevitable and do not try to avoid it until the last second. This is wrong. It is worth remembering that not all aircraft are equipped with an emergency fuel dump system.
Even if a crash occurs, a much smaller percentage of passengers die from burns or smoke than most publications claim. According to NTSB statistics, passengers who are involved in a major plane crash are much more likely to survive.
Question: What happens when a pilot dumps fuel? Does it dissipate and subsequently evaporate? And where is it usually prescribed to do this, over land or over water?
Answer: Yes, if necessary, fuel is discharged through a special nozzle, which disperses it into tiny droplets. Fuel dumping itself is permitted only in specially designated areas. To minimize impact on residential areas, we also must not harm people on the ground.
Question: In the past, almost all aircraft models were equipped with an emergency fuel dump system, but modern aircraft models usually do not have this system. Why did engineers abandon this safety system and are there any worthy alternatives to it in modern aircraft?
Answer: Modern aircraft, unlike their predecessors, are equipped with an emergency landing system when overweight, which gives pilots the opportunity not to make an emergency dump of excess fuel. After such a landing, the aircraft undergoes a thorough check to eliminate any problems and ensure that the aircraft is fully operational and ready to fly.
Each of us has used airline services at least once in our lives. They offer the safest and most comfortable mode of transport. In addition, with its help it is possible to significantly reduce travel time.
Surely many have seen a picture of a plane circling over the landing strip for hours and wondered: why is it doing this? After all, due to the extra hours of flight, a lot of aviation fuel is burned. This is exactly what a pilot achieves when he deliberately flies in circles without landing. He tries to burn as much fuel as possible. We’ll talk further about why the airliner runs out of fuel before landing.
Weight of the “iron bird”
When taking off, as when landing, the weight of the airbus is extremely important. Moreover, in each case it is calculated separately: for landing - landing, and for take-off - take-off.
The take-off weight of the aircraft is calculated taking into account the total weight of passengers, their luggage, the aircraft itself and fuel.
Moreover, if the weight limit is exceeded, the plane will not be able to gain the required altitude or will not take off at all.
The landing weight of the “iron bird” is calculated in the same way. The total weight of the crew and passengers, the aircraft itself and the luggage on board is also taken into account here.
Aircraft weight upon landing
There is a strictly limited weight of an aircraft approaching to land. Under no circumstances should this limit be exceeded, as this situation could cause an airliner to crash.
During landing, a kind of impact occurs between the landing gear and the surface of the landing strip. At the same time, the chassis and fuselage are designed for specific loads, which directly depend on the weight of the side. If this indicator is significantly exceeded, then the load will increase accordingly. The landing gear and fuselage may fail and break under the weight. The wings may also be damaged. That is why it is important to monitor the weight when landing.
Fuel dump
As a rule, the landing weight is slightly less than the takeoff weight. How is this possible, you ask? Everything is very simple. Any airbus is designed to use up most of the fuel from the tank during the flight. Thus, when landing it will weigh less than when taking off.
What to do in cases where the landing takes place earlier than planned? The reason for this may be an emergency or a change in flight course. In this case, all the fuel will not be consumed, because the plane’s path will be shortened. But landing with fuel in the tank is also dangerous.
In this case, some aircraft equipped with a special emergency fuel dump system can simply drain the fuel. If there is no such system, then the pilot has to circle over the landing strip, using up the remaining fuel. It will also have to be consumed if conditions do not allow the dumping of this fuel.
Is it true that planes dump their remaining fuel before landing?
The most interesting thing is that today planes practically no longer dump fuel. Previously, airplanes had such a reserve of fuel that they were designed only for the flight; in case of an unscheduled landing, the airplanes either circled the airfield to burn off the remaining fuel, or dumped it to prevent ignition during landing. Now progress has moved forward. Now a special powder is thrown into the fuel tank, which simply makes the fuel non-flammable and does not need to be dumped.
Today, such a phenomenon as fuel dumping practically does not occur in the flight practice of civil aviation pilots - and even on the contrary - they are rewarded in every possible way for saving fuel - this is a business today and only in the event of an emergency will pilots dump fuel. If fuel is constantly dumped, then an environmental disaster will quickly occur on Earth.
Airplanes do not dump remaining fuel before landing.
There is no need for them to do this if everything is going according to plan and the landing is not an emergency.
But if you need to land urgently, or an emergency situation has arisen, then there are rules that the crews of air vehicles are forced to adhere to, and in which the plane must be landed after dumping excess fuel.
Yes, this really happens in the event of an emergency landing. Once there was a rowdy passenger on board, whom the flight attendants could not calm down. It endangered the safety of passengers and cabin crew. And the pilot decided to land the plane. An emergency landing was made at the nearest airport, but there was a lot of fuel left in the tanks. As a result, the pilots had to dump fuel. The rowdy was arrested after the flight, and the airline sued him and recovered a large sum of money. The same can happen if there is a sick passenger on board or an emergency on board where an emergency landing is necessary.
Fuel is dumped only during an emergency landing immediately after takeoff. Kerosene costs a lot of money, so no one will dump it unless absolutely necessary. A black trail usually occurs not during landing, but during takeoff, when the engine is operating at maximum power in afterburner mode; the trail is left by soot from unburned kerosene residues.
An airplane dumps fuel when it is forced to make an emergency landing due to the risk of an explosion. The more fuel left in the tanks, the stronger the explosion may be in case of failure. If the landing is unplanned, but not an emergency, then the fuel is burned.
Here Sergey Rakitin answered absolutely correctly that the plane dumps fuel only in case of a forced landing, immediately after takeoff or somewhere in the middle of the journey, but even then if the situation allows, then kerosene does not reset, and is maximally developed to a safe weight. Emergency reset This is done only when the plane, for some emergency reason, cannot fly in circles while running out of fuel.
Landing an airplane with a large amount of fuel on board is risky. The flight route and refueling of the aircraft are calculated taking into account that there is enough fuel to reach the alternate airfield and that after landing at such an airfield there is still approximately one to three tons of kerosene left (this is for large airliners).
In the event of an emergency fuel dump, not a black trail will be visible from behind the plane, but a white one. The black trace is, as Sergey Rakitin writes, just soot and soot from kerosene.
Airplanes dump fuel only in case of an emergency emergency landing to avoid fire. In some cases, if the situation allows, the crew continues to fly specifically in order to maximize the fuel supply. And no one dumps fuel on purpose.
During emergency landings, fuel dumping is necessary. And a reset is made only in the case when it is impossible to reduce the amount of fuel simply by producing it. Planes simply fly in circles, running out of fuel. If this is not possible, then reset at high altitude.
By reducing the amount of fuel, the aircraft crew reduces the possibility of an explosion during an emergency landing and, accordingly, a fire.
When designing an aircraft (both civil and military, by the way) and in particular its landing gear, there is always such a parameter as the maximum landing weight. It is quite obvious that this is the maximum weight that the landing gear will support during landing.
When an aircraft is being prepared for a mission, it is filled with enough fuel to fly to the planned landing site + navigation fuel reserves. When everything is normal, the fuel is not drained. If the crew decides to land the vehicle and its weight exceeds the maximum landing weight, then the fuel is disposed of. To say that the aircraft burns fuel so that the load on the landing gear during landing does not exceed the maximum, otherwise the landing gear simply will not withstand it.
Such situations occur especially often in the event of a serious failure immediately after takeoff. It should also be noted that not all aircraft simply “burn” fuel in order to “lose weight”; some are equipped with an emergency fuel drain system.
To summarize, we can say that the aircraft burns fuel so that the load on the landing gear during landing does not exceed the maximum, otherwise the landing gear simply will not withstand it.