Hot answers tagged

60

Mass doesn't affect the maximum distance, only the maximum endurance. For example, image two identical planes A and B: A weights 50kg less than B. Assuming no wind (horizontal / vertical) and speed of best glide, both gliders will land at the exact same spot. The lighter airplane A however will arrive later than B, as the speed of best glide is less than ...


47

It isn't practical for a number of reasons: Intentional stalls are inherently dangerous. Stall-spin accidents are a major cause of accidents, stall recognition and recovery are taught specifically to avoid stalls. Some airplanes have docile stall characteristics, but even those can still bite you. A Cessna 172 will drop a wing if mishandled, especially ...


35

Nothing out of the ordinary here. You probably arrived at the airport a little bit earlier because ATC allowed your plane to go directly to the runway instead of taking a longer route (as confirmed by the radar data from FlightRadar24). It was probably a quiet moment at the airport and there was no need for your plane to fly to the back of a queue. Since you ...


28

According to FlightRadar24 here: at one point your flight was descending at more than 4000 feet per minute. This is a bit faster than usual, especially for the (relatively) low altitude you were at at the time. However, that is still well within the normal safe flying capabilities of the 737. In an emergency, when the plane needs to get down fast, they will ...


26

If you can forgive my limited Paint skills: It's the variable/constant speed that makes the difference. Weight changes endurance (time to ground) and not range (distance to ground) if speed is adjusted to match the new weight. Weight changes the speed for best L/D, but does not ever change the best L/D ratio (and thus best range) For gliders (which are ...


26

The economics of descent planning Normally the pilot wants to descent in an economic manner and also try to keep passenger comfort in mind. Let's start with the "economic" descent: An airplane will generally consume least fuel per distance at its "optimum cruising altitude". The exact altitude is dependent on the type of plane, the wind ...


25

Very frequent. Modern airliners are certainly fairly slippery, but it's not so much that they're super-gliders that we can't wrestle down onto the ground. It's more a function of busy airspace than a property of the aircraft. When you remove power from any aircraft, it's going to descend - the only question is the rate. I promise you that if you found ...


25

Airline pilots certainly do use gear/flaps/spoilers to descend more quickly if needed. However, SOP typically requires an approach to be stable upon reaching a certain altitude on the approach. This means having speed and airplane configuration set for landing, and being lined up with the runway and on the glideslope. Unstable approaches are more likely to ...


23

In addition to the other answers, let´s look at this L/D(=E) diagram of the enticing DG-1000 from DG Flugzeugbau (but fear not, 'tis true for all gliders) : The best L/D ratio is equal for different wing loadings, but is occuring at different speeds - the higher the load, the higher speed. You can also see that the minimum/stall speed is also higher for ...


21

You don’t need a new technique You don’t normally stall jetliners. And in a crisis the last thing you want to do is learn a new technique. Besides, they already have a trained practice for descending jetliners very quickly. It’s used for loss of cabin pressure. While the procedure normally levels at 10,000’/3000m, it could certainly be extended. Anyway, ...


19

Normally, a stall and controlled flight are mutually exclusive. That AF447 would descend as it did has to do with the relaxed static stability of the A330 and its rear cg location as well as the docile behavior of its airfoils with large separation on the upper side. In short: With some aircraft this is indeed possible and practical but with others it is ...


18

Glide ratio is the ratio of the distance a glider can travel horizontally to the altitude lost in transit. For instance, if a glider can travel 40 miles horizontally while losing one mile of altitude, the glide ratio is 40:1 (typical for a medium-high performance glider). The best glide ratio or maximum glide ratio is simply the best ratio a glider can ...


18

Using liveatc.net was somewhat helpful; more helpful was using a silence skipper. Hawaiian Thirty (HAL30) can be heard with: Sector 5 in the 6:00z recording (liveatc.net; archive.org) at 15, 19 and 28 minutes in. PDX Area in the 6:00z recording (liveatc.net; archive.org) at 28 minutes in. (Timestamps apply to the downloaded mp3s and not the site's/browser'...


17

Whether there are any formal policies for when to request descent will depend on the airline. However, I doubt formal procedures are established, since it should be pretty obvious to pilots when to request descent. From a controller point of view, I will expect you to request descent when you are ready for it - so a minute or so before reaching your top of ...


17

A couple of things that get drilled into you in first aid or emergency response training is 'if you aren't part of the solution you're part of the problem', second is 'don't become a casualty.' In other words, don't be a hero. In the scenario you describe there's going to be yelling and screaming from all around, raising your voice isn't going to help the ...


16

There are a few possibilities, there's no way to know which is correct without more information: There could have been an emergency on board. If someone is showing signs of a serious illness pilots will get the plane on the ground in a hurry to get the person medical attention as soon as they can. Or there could have been an issue with the airplane or a ...


16

Descent planning for jets can get a little tricky at times, and you have pointed out some of the things to look at when deciding when to start down (assuming that ATC gives you the option to choose your own top of descent). The descent point is dependant on your aircraft and how much drag there is at your descent speed. Anything that adds more drag allows ...


16

I actually got asked a similar question on a checkride two weeks ago. Right after I was asked to demonstrate an emergency descent through a hole. I heard the talk about the advantages of the substantially increased drag of the Fowler flap, and was quizzed about impact of drag with higher speeds. Meanwhile I extended full flaps, and slowed the plane. ...


15

If the pilot reduces the airspeed while he increases the rate of descent, you will not notice any change in pitch attitude when the aircraft descends. With jets you should be able to hear a change in engine pitch when thrust is reduced. Turboprops run their engines at constant speed, and a reduction in power here means a reduction in propeller pitch. This ...


15

I’ve been a passenger on a plane in an emergency depressurization. The first thing to realize is that everything happens amazingly fast. Even as a (GA) pilot myself, it was almost over before I even realized what was happening. The second is that pretty much everyone on the plane grabbed their masks and started putting them on as soon as they dropped, then ...


14

FLC mode maintains airspeed during a climb or descent, while VS mode maintains a specific vertical speed. Often air traffic controllers will request that you "maintain 250 knots in the descent" or something to that effect, which is much easier to achieve when using Flight Level Change. As another answer points out, by maintaining airspeed, climbs are made ...


14

It is smarter to roll onto your side and maintain unstalled flight, executing a emergency spiral descent. G loads on the wings are much lower as there is no need to maintain altitude, only to control airspeed. With all due respect to our beloved Langewiesche, "mushing glide" technique is for much lower wing loaded gliders that are easily unstalled ...


14

Best thing you can do is remain calm, and let the trained personnel handle the situation. Panic is a state of mind impenetrable to reason, and you being a random person amongst passengers will absolutely not help in communicating with your peers. One of the major reasons for crew wearing uniforms is that it gives them authority. This helps them control the ...


13

I'm tuning in more than 3 years late because I'm not fully satisfied with the answers here. Yes, Lnafziger, when you want to stay up as long as possible, the plane should be as light as possible. But sometimes you need to get down fast: This is when water ballast is added. Force is right: Water ballast speeds everything up. But there is more to it. Also ...


13

Basically, it's a combination of historical significance, passenger comfort, and ease of mental calculation. Historically, before aircraft were pressurized a rapid descent would be uncomfortable for passengers. At the speeds typically flown, a 300ft/min descent was deemed to be comfortable enough for the typical passenger. Many aircraft had a cruising ...


13

For a comfortable decent you generally want to come down at 500 Ft/Min on the Vertical speed indicator. The 152 is doing about 95Kts over the ground (assuming no wind). So you are covering about 1.5 miles a minute to round it off. So you need to drop 5000 ft on your approach to the area. At a comfortable rate that will take about 10 minutes. In that time, ...


13

There are two reasons I can think of off the bat: Its possible the controller asked them to hold a slow speed due to increased traffic ahead. The brakes may have been deployed to match the speed requested. I have heard this called on occasion over the radio in the terminal area I fly. The controller cleared them for a steeper decent than usual this would ...


12

Normal descent rates will vary by operator and by airframe, but in general they follow this logic: Power at flight idle, Airspeed at or near max mach number or max KIAS, Spoilers stowed. Generally they wont push airspeed right up to the limits and incorporate a small margin, but this is general idea. This is the most efficient descent because it means you ...


12

If the pilot commands a certain glide path angle, any change in airspeed will also change vertical speed, because both are connected by the glide path angle $\gamma$. Note that the vertical speed is air speed$\cdot\sin\gamma$. Climbing or descending makes no difference; only the sign of $\gamma$ changes (positive $\gamma$ means the aircraft climbs). Also ...


12

For ATC planning of jet transport aircraft, 3NM per 1000 ft, plus 10 NM for deceleration is used as a rule of thumb. $$FL300=3\times30+10=100NM$$ Most of the 10NM for deceleration will be consumed at around FL100. Weight should not change the descent distance a lot, it mainly affects the speed. The lighter the slower.


Only top voted, non community-wiki answers of a minimum length are eligible