82

Aircraft altitude is measured (inferred) by atmospheric pressure. The aircraft is usually flown at an altitude that maintains constant ambient pressure (by pilot or autopilot, as the case may be). Changes in local barometric pressure (provided by air traffic control) are used to recalibrate the aircraft altimeter. As long as the aircraft is flown at a ...


74

The engine in a typical light airplane (say a Cessna 172 or a Piper Cherokee) has a lot in common with the engine in a classic 1960s VW Beetle (Type 1): Both engines are horizontally opposed four-stroke four-cylinder spark ignition gasoline engines. Their parts even have similar metallurgy, and broadly similar failure rates. In fact if you remove the gearbox ...


71

There is no adjustment needed as the aircraft will naturally follow the curvature of the earth without any input from the pilot. This is because the aircraft flies through the atmosphere which also follows the curvature of the earth.


64

I'd like to answer this question by debunking the premise of the question: that most plane crashes happen when planes fall out of the sky, and that it's like rock climbing where the higher you are, the more likely a fall will kill you. While it sounds believable, it's almost entirely false, and since it isn't diving out of the sky that kills you, lowering ...


61

It would likely create a more deadly situation. In aviation altitude is your friend. Generally speaking altitude in the case of an emergency buys you time to work the problem. Generally you want to be as high as practical for the aircraft in question. Altitude also buys you glide distance to find a suitable landing location in an emergency. Airplanes ...


55

There is an excellent answer at http://scottlocklin.wordpress.com/2014/07/21/can-the-su-25-intercept-and-shoot-down-a-777/ The SU-25 is a ground attack fighter unsuited to intercepting and/or shooting down 777s. If the Ukrainian air force wanted to do so, they have better aircraft available. The SU-25 max speed is slower than a cruising 777. The SU-25 has ...


45

The simple answer is that the Concorde had no single assigned altitude, it was allowed to climb freely above ~FL450; this is discussed in depth in episode 166 – Flying the Concorde (worth the listen as it answers just about every Concorde question!). As @pilothead alludes to in their answer it climbed as it burned fuel but the aircraft never actually ...


42

In short: acclimatization, both chronic and acute. During your Tibet-trip, you had probably spent days at high altitudes, allowing your body to acclimatize to the lower oxygen partial pressure (similar to how some elite endurance athletes prepare themselves for competition), by increasing your hemoglobin count (and other mechanisms), making you better ...


41

You're asking 4 things here: Can aircraft fly higher than their stated service ceiling? Service ceiling can be exceeded, depending on the aircraft type, loadout, atmospheric conditions, and flight profile, but usually not very far or for very long. Does an SU-25 have afterburners? The SU-25 (NATO reporting name Frogfoot) has no afterburners, so that part ...


39

Quite simply, it's because sometimes you fly below sea level. There's a couple stories out there of aircraft navigation systems acting a bit odd due to their flight below sea level. For example, there is this one, which involves a C-130 landing on an airfield that is 1,210 feet below sea level. There are numerous areas in the world that are below sea level. ...


37

Flight levels use QNE or pressure altitude, while altitude references QNH or local pressure adjusted to sea level pressure. Altitudes are used at low levels and flight levels at higher levels. The transition between altitudes and flight levels differs by country and is generally just above the highest obstacle in that country. In the US the transition ...


33

A plane descends when it does not have enough thrust to maintain its altitude. A plane can descend with its nose pointed up or down so long as there is not enough thrust to maintain altitude. Altering the pitch of an aircraft is used to control airspeed: pitching up slows an aircraft down (and may cause a climb if done from a level attitude) and pitching ...


31

For the stalled flight to recover, the nose needs to be pointed in the airstream, and then the aircraft pulled up with load factor below the ultimate load. From the accident report: The recordings stopped at 2 h 14 min 28. The last recorded values were a vertical speed of -10,912 ft/min, a ground speed of 107 kt, pitch attitude of 16.2 degrees nose-up ...


29

The pressure in the cabin does not remain the same. It decreases, but much more slowly, in such a manner that when the aircraft is at 37000 feet the pressure in the cockpit is the equivalent of 7000 or 8000 feet. Keeping the cabin pressure at sea level would pose incredible stress on the fuselage, due to huge difference in pressure between the inside and the ...


28

There isn't an adjustment for altitude. An aircraft flying level at a given altitude and trimmed for level flight will stay at that altitude. That means the flight path will have a gentle nose-down curve (looking from far away from the earth) as the direction of down (towards the centre of the earth) changes. Think about the gravitational potential energy ...


27

There are many examples of aircraft with high service ceilings. While most commercial aircraft have service ceilings of FL410 and rarely fly even that high, many business jets have a service ceiling of FL510, such as the Dassault Falcon 7X, Gulfstream G650, and Bombardier Global Express. That being said, military jets can fly higher and will be talking to ...


27

The only reason for your flight to operate at such low altitude is because it is cheaper for them to do so. As you said it is due to weather, other route/altitude may not be available. They can cancel the flight but that is likely to be costly. They may have to find accomodation for you and crew until they can put you to the next flight. Sub-optimal flight ...


26

An airship pilot has three ways of adjusting lift: Every lighter-than-air vehicle needs some ballast to adjust its weight. This could be sand, but mostly water is used. A blimp is only partially filled with helium. The envelope is held taut by filling a bag inside with air, called a ballonet. If you press a little more air in this bag, the overall density ...


26

I used the playback function of Flightradar24 for the 18th at 23:00 UTC, and the amount of traffic above 10,000' (filtering by altitude) seemed very normal compared to other days. I'm baffled as to why they flew so low, but I can address your fuel question in some detail. The difference in fuel consumption is ~693 kg of fuel, and would cost an extra ~$415, ...


25

Altimeters are calibrated to a standard atmosphere model (International Standard Atmosphere, ISA). What the altimeter shows you is the vertical distance between the altitude equivalent to your current pressure (pressure altitude) and a reference "pressure altitude". The reference pressure altitude is set in pressure units (hPa or In. Hg) on the altimeter ...


24

There's no legal limit of how high you're allowed to fly by law: there's no law that says It is illegal to fly above X,000ft In some juristictions there are more specific laws, eg It is illegal to operate an unpressurised aircraft above 25,000ft However, each aircraft has a service ceiling when it is certified, and it would be generally illegal to ...


24

Looking at the route your plane took, this low altitude flight was likely to avoid the polar jetstream. This is a band of wind that blows west to east in roughly the area the first half of your flight was flying through. It exists mostly between 30,000 and 39,000 feet altitude, and can range from about 60mph to over 200mph. I suspect that the low altitude ...


23

Concorde had a 10,000fpm climb and a max altitude of 60,000ft, so time to climb was not a problem. It had an optimum cruise altitude that varied with weight, so as it burned fuel it climbed higher to stay on the optimum. There were no other aircraft operating at those altitudes, so it would get clearances to climb 15,000ft at a time and would cruise climb ...


22

Severe convection will have anvil tops at the tropopause and overshooting tops can penetrate much higher (severe thunderstorm warnings often use a value of 60,000 ft for threats to aircraft). How high the overshooting tops can get is a balance of the positive buoyancy during parcel ascent against the negative buoyancy once it gets into the warming ...


22

Typical height for helicopters is 500-1,500 AGL, and almost all flights are conducted in this regime. Below 1,500 AGL the surface is quite close and the ground moves by fairly quickly, so you have a good point of reference. At 3,000 AGL, you can feel quite disconnected from the earth and can have a bout of altitude fear. When I had to circle up above ...


22

At lower altitudes, "useful" consciousness doesn't end when you are unable to act. Rather, what happens is that your ability to make sound decisions and carry them out effectively degrades: for example, instead of responding to an alarm buzzer by figuring out what's causing it, you might simply hit the "silence" button, or you might be so fixated on keeping ...


21

The brief period of leveling off is not unique to the flight on that day. Looking at track logs for previous days, it always levels off at around 7,000 feet for some period. As Terry commented, this is most likely to deal with the congested airspace. Other routes coming into and out of the London area probably pass through the same space, and keeping ...


20

Like with fixed wing aircraft, it is called the ceiling. Usually two ceilings are distinguished; service ceiling, where the aircraft can still achieve a positive rate of climb of either 100 fpm (propeller) or 500 fpm (jet). absolute ceiling, the theoretical altitude at which no positive rate of climb can be achieved. In other words: the maximum altitude at ...


20

This is more of a physics question rather than an aviation question. While other answers have addressed the question from the aerodynamics point of view, let me try answering it from a physics perspective: frame of reference. Frame: where are you going? How do you know an object is moving? The answer is you don't - there is nothing like a "fixed absolute ...


20

When asked for altitude, you report the altimeter reading, utilizing the correct barometric pressure entered into the Kollsman window. ATC separates traffic based upon indicated altitude. The indicated altitude may include errors, such as the pressure ATC provides, but all aircraft in the area will presumably be using the same barometric pressure, and will ...


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