My understanding is Pitch Trim should hold current Pitch position, Roll Trim should hold roll position and Rudder Trim should hold Rudder position to relieve pilot of holding the yoke/stick or pedal continuously.
But why there is Up-Down/Left-Right (Pitch/Roll) switches on yoke or stick?
Appreciate, explanation of trim fundamental with respect to this.
The basic idea is that you adjust trim to relieve the control forces that you would otherwise have to hold. For instance, any time that you change airspeed, the amount of air passing over the elevator changes and changes the amount of nose up/down force that it creates, requiring you to hold pressure forward or aft on the yoke in order to maintain the new airspeed. You would then adjust the pitch trim to neutralize that force so that you don't have to hold it. Because airspeed (and therefore pitch trim) is changed so often during the flight when hand flying the aircraft, it is very convenient to be able to adjust it right on the your where you hands already are. Not as many airplanes have aileron trim on the yoke since you don't need to change it as often, but the idea is the same.
I might be mistaken, but it appears to me that you're missing an important piece on how trimming works. It's not a button you press to magically remove the control forces, but rather, you need to adjust the trim tabs (on most smaller aircraft at least, some aircraft, especially new large ones, have other mechanisms, but that's outside the 'basics' scope) to achieve the desired result.
I'll use the elevator as an example, but it applies to ailerons and rudder as well. This is a common image used when showing trim tab movement:
Basically, the trim tab extends into the airflow, pushing the elevator in the other direction. This is key though, as it's using airflow, its effectiveness diminishes when airspeed is reduced and it becomes more effective when airspeed is increased, which is exactly how the elevator itself is affected. This means that, should the airspeed change, both elevator and trim-tab will be affected the same way and the forces, and as a consequence the elevator deflection, will remain in an equilibrium. Maintaining a specific elevator deflection will cause the (aerodynamically stable) aircraft to remain at a selected angle of attack and therefore airspeed. In order to change airspeed, you need to change angle of attack, and so you need select a different elevator deflection, prompting the need to 're-trim' fairly often during a flight, especially during departure and approach. This applies to elevator trim, I've never flown with (in-flight adjustable) aileron or rudder trim, but I assume it is primarily used to counter effects of engine torque and P-factor, so it would be adjusted whenever you're changing the power setting.
You could, theoretically, skip the trimming step and hold it with arm strength, but your arms would eventually go numb and it would be virtually impossible to keep it on airspeed while accomplishing the other tasks in the cockpit during high workload periods. The March/April 2014 issue of FAA Safety Briefing talks a bit about trimming, and mentions that the Weber-Fechner law, which discusses the concept of Just-noticeable difference, states that you need about 14% of difference to the pressure you're manually holding to notice a difference, so trusting the feel of your hand pulling the yoke is not a particularly good idea. I do believe some aircraft, in particular larger ones, would require more force than humanly possible for the needed elevator deflection in certain situations, suggesting the need to use trim, but I might be mistaken on that point.
The movement of the trim tab is sometimes driven by an electric motor (or otherwise powered, hydraulics for example) in which case you have up and down buttons, and sometimes it's manual, in which case you usually have a wheel which can be rotated to pull the tabs up or down.
Up and down, which is often referred to as 'nose up' and 'nose down', signify what kind of control forces you want to remove. If you find yourself constantly pulling the nose up to maintain the desired airspeed and attitude, you'll need to apply nose up (or 'up') trim while simultaneously releasing the back pressure and vice versa. This sounds harder than it is, it just means you hold the yoke in place, and you will notice the amount of pressure needed to hold it there drops until it's completely gone. This is one of those things which is actually harder to do in a home simulator than in real life, as you'll have to move the control while applying trim. Note that the 'up' and 'down' labels do not mean the tab will move up or down, remember the tab travels in the opposite direction of the elevator, and to pull the nose up, the elevator needs to move up into the airflow, meaning the tab will actually move down, as can be seen in the picture.
As a bonus; in aircraft with no autopilot and autothrottles, if you do not apply any control forces the aircraft (aerodynamically stable) will maintain a particular airspeed. This means that for a specific configuration (flaps, landing gear, weight, power, etc) it's possible to trim the aircraft for a specific speed, this is very handy when it's crucial to maintain a specific airspeed such as during departure or approach.
This also means, which might not be obvious for someone not familiar with aircraft, that it's not possible to trim an aircraft to maintain altitude. Sure, there's usually a specific airspeed which will keep the aircraft in level flight, but that's only until you enter the next up- or downdraft, or until you've burned off a bit of fuel and aircraft has become lighter. So you will either need constant speed or power adjustments to keep it on altitude, most aircraft without autothrottles use the former.
Consider the following scenario: You're in a 747 close to touch down and you see another airplane taxi onto the runway. You're trimmed for landing, with the engines burning about 3,000 lbs per hour each, but now you go to go to max power to go around so you're going to give each engine around 20,000 lbs per hour (from old memory so don't quote). You're going to need a lot of trim change very quickly, and that need is going to continue while you clean up the airplane.
Never heard of aileron trim on the yoke.
My understanding is Pitch Trim should hold current Pitch position, Roll Trim should hold roll position and Rudder Trim should hold Rudder position to relieve pilot of holding the yoke/stick or pedal continuously. But why there is Up-Down/Left-Right (Pitch/Roll) switches on yoke or stick? Appreciate, explanation of trim fundamental with respect to this.
Quoting from page 162 of the book "Fatal traps for helicopter pilots" by Greg Whyte: Hydraulic jack stall (servo transparency) in (AS-350) helicopter is an aerodynamic phenomenon can occur when the helicopter is flown outside it is normal flight envelope and subjected to positive maneuvering (g-loading). It results in uncommanded aft and right cyclic and down-collective motion accompanied by pitch up and right roll of the helicopter. My question: What is reason for uncommanded aft and right cyclic collective down pitch up and right roll?
Provided an aircraft with a fly-by-wire system, there are basically two possible choices when it comes deciding how to let the pilots interface with it: rate control / attitude hold: a deflection of the stick will command a certain rate, releasing it will make the system maintain the current attitude. See the Airbus Normal control law. direct control: a deflection of the yoke will directly translate to a deflection of the surfaces, mimicking the "old" mechanical control setup. It is my understanding that this is the design choice of Boeing in its new aircrafts. I do not wish to discuss
I have a question regarding this Missed Approach Procedure Im in my final approach segment and reach DME 1.1 and the runway is not in sight so I start my Missed approach, how should it be executed? Since I have to hold I'd start a tear drop entry turning to heading 125° and then left turn intercepting 275° course inbound. This option sounds viable to me I first do a right 360° as charted (???) and going to the VOR and then starting probably a parallel entry into the hold. This doesn't sound viable to me Textual description is also clear about that 360° If it 1.) why would they chart
I've never seen a 727's aft stairs open, but presumably, based on an Wikipedia image and common sense, they do reach the ground when the aircraft is on the ground. Furthermore, (as I understand it), airliners land with a positive pitch, which means that assuming a level runway, the rear of the aircraft will touch down first. However, this suggests that if the aft stairs of the 727 were open during landing, they would impact the ground during landing and, given the pitch, do more than scrape the ground and cause damage to the aircraft. However, DB Cooper's jump left the aft stairs open
I've heard three methods you should use in a multi-engine aircraft when engine-out, each recommending a different amount of bank: Wings level, hold aileron to maintain roll and correct using rudder. Ball centred, ailerons flush and correct using rudder. 5 degrees bank angle, hold aileron to maintain roll and correct using rudder. Which one of these will result in the highest climb rate, and are there any advantages to other methods which don't give the best climb rate?
As a private pilot I have zero knowledge about how big jets are being flown so I was a little surprised to see that smaller Airbuses (A32x) only use spoilers for roll control on final approach. During the initial phase of the approach ailerons are being used but at a certain point they stay put in the neutral position and roll is controlled by the spoilers. When I mentioned this to the pilot when exiting the aircraft he was a little annoyed by the question and he said I must have seen it wrong. I've seen this numerous times since then so I'm pretty sure I wasn't mistaken. Is this actually
In flight training, you're always told not to cross-control, (for example, rolling right aileron, and stepping on the left rudder), but it seems to me that is exactly what a slip is doing. Is it that a slip is intentional, and a cross-controlled situation is typically unintentional?
I know that historically pilots used to trim an aircraft to relieve continuous application of force during climb/cruise/descent, and at that trim tabs existed on control surfaces (elevator, ailerons, etc) which could be used to hold the position of the control surface without the pilot applying any force. But now, we don't usually have trim tabs, and with fly-by-wire systems forces have been...? Apart from pilot workload and fuel efficiency (I know that trimming an aircraft can produce drag), what other benefits does trim offer? Without trim tabs, how is trimming accomplished?
On the sidesticks of Airbus aircraft, there is a Priority Takeover button. Wikipedia has this to say: In typical Airbus side-stick implementations, the sticks are independent. The plane's computer either aggregates multiple inputs or a pilot can press a "priority button" to lock out inputs from the other side-stick. On US flight 1549, the CVR transcript shows that Sully hit the Priority T/O button, after the co-pilot (Skiles) handed over control of the aircraft: 15:27:23.2 - Sully: My aircraft. 15:27:24.0 - Skiles: Your aircraft. 15:27:26.5 - FWC: Priority left. I'm