Is there an explanation for this? A: Subsonic jets are most efficient around 40, feet. Jet engines are much more efficient than they used to be, but the altitudes have remained relatively constant due to the cost of flying higher and the limited benefit.
Q: When approaching stall speed in a commercial airliner, can a pilot without engine power maintain level flight, thereby avoiding a wing from dipping down and increasing the chance of a sudden crash? A: Stalls are not related to engine power. A stall occurs when the air flowing over the wing is no longer attached to the wing and producing lift. Perhaps now there'll be a more formalized approach to that aspect of our craft. Back to basics, back to basics, training, training.
In the begining, in the middle and during high time flying. Flying the basics will never ends, being part of the whole process. Nice flights Happy landings for all. My instrument instructor had me do several sessions of partial panel flying. Merely holding the same Pitch Attitude and Power Setting and ignoring the three associated Pitot Static Indicators would have kept them out of trouble.
There a many things that cannot be accurately depicted in the simulator. Windshear recovery comes to mind, because of varying factors. In training, there should be demonstrations showing different factors eg. How much education have you had in high-altitude aerodynamics - or any aerodynamics for that matter - but at least before you began flying jets? In a word; use gliders. They are inexpensive high aspect ratio airfoils and force pilots to use ONLY aerodynamics instead of engine performance to resolve angle of attack issues.
I'll probably get lambasted for saying this but so what. As a glider pilot, we learned all about coffin corner, adverse yaw, etc. As Bach related it, the students in this hypothetical school build and fly balloons and gliders, not unlike those built and flown by the early pioneers of flight. Then the students move to building engines and powered airplanes and flying them, too, continuing this step-by-step approach to more complex aircraft.
They learn to recognize when their aircraft is reaching the limits of its capabilities and can tell when the engine is running poorly by its sound. Their experiences serve them well, regardless of how heavy, fast or complicated the aircraft they eventually fly are. It was the ultimate flight training for real pilots.
Nevertheless, the point is sound. As many others have said in so many words, pilots need good initial training and much experience in the basics and good recurrent training in both common and rare emergencies. Admitting that we don't 'know it all'. Re-learning basics. Quality training. All of us come from different aviation backgrounds and have had different aviation experiences that we tap into throughout our careers.
All of us have 'holes' in our knowledge and understanding, either by never learning a topic, never learning properly or having forgotten. The hardest thing for an experienced pilot to admit about any aviation-related topic is "I don't understand this".
Most of us make it through a career with 'holes', never falling into them, or flying with someone that doesn't have the same holes. But for those valiant AirFrance and Colgane crews, they shared the same holes at the wrong time. What a wealth of informed comment! After 50 years from Tiger Moth to Gulfstream via the RAF I am amazed that there now have to be special schools for upset training and situational awareness.
Isn't that what pilots do to become proficient? I was fortunate to have had high altitude training in a single jet but not before a comprehensive aerodynamics course.
Ask any navy pilot about AoA, the unsung hero of aerodynamics. Not just for high speed jet jocks, it also shows the most efficient configuguration in cruise. It has kept me out of trouble when in the Q corner in turbulence and unable to raise ATC for a lower level. Rolland's comment on the number of systems needing pitot input is particularly relevent.
Wasn't Sully a glider pilorichardc-j. Once the airplane is stalled, it will lose altitude about feet per second. The pilots have to unstall to stop severe altitude loss by lowering the nose by manually reposition the All Flying Horizontal Stabilizer Trimmable Horizontal Stabilizer - THS nose down. If close to the ground, reducing altitude loss would be of up most importance during the recovery. A stall at high altitude would allow a generous degree of nose down pitch and altitude loss during the recovery.
Air France and other airlines need a serious review of basic aerodynamic facts and amend their stall recovery procedure. The crash of Air France flight into the Atlantic Ocean, killing all passengers was caused by the co-pilot induced stalled glide condition and the airplane - Airbus A remained in that condition until impact.
To recover from stall is to set engine to idle to reduce nose up side effect and try full nose down input. Pilots lack of familiarity and training along with system malfunction contributed to this terrible accident. Also the following contributed to the accident 1 the absence of proper immediate actions to correct the stalled glide 2 Insufficient and inappropriate situation awareness disabling the co-pilots and the captain to become aware of what was happening regarding the performance and behaviour of the aircraft 3 lack of effective communication between the co-pilots and the captain which limited the decision making processes, the ability to choose appropriate alternatives and establish priorities in the actions to counter the stalled glide During most of its long descent into the Atlantic Ocean, Airbus A was in a stalled glide.
Far from a deep stall, this seems to have been a conventional stall in which the Airbus A displayed exemplary behavior. The aircraft responded to roll inputs, maintained the commanded pitch attitude, and neither departed nor spun. The only thing the Airbus A failed to do well was to make clear to its cockpit crew what was going on. Its pitch attitude was about 15 degrees nose up and its flight path was around 25 degrees downward, giving an angle of attack of 35 degrees or more.
Its vertical speed was about knots, and its true airspeed was about knots. It remained in this unusual attitude not because it could not recover, but because the co-pilots did not comprehend in darkness, the actual attitude of the aircraft. The co-pilots held the nose up.
Induced drag is directly related to lift production and is greatest at low speeds and high angle of attack. Conversely, parasitic drag increases in proportion to the square of the aircraft speed.
Total drag, at any given speed, is the sum of its two components and, as can be demonstrated graphically, its minimum value occurs where the induced drag and parasitic drag curves intersect. The speed corresponding to the point of minimum total drag is known as the minimum drag speed or V imd sometimes V md and will vary as a function of aircraft weight.
Obviously, level flight at speeds greater than or less than V imd is possible. To fly slower than V imd , a greater angle of attack is necessary and an increase in thrust is required to compensate for the increase in induced drag caused by the increased angle of attack. Angle of attack can be increased to the point that there is insufficient thrust available to maintain level flight or until reaching the wing's stall angle of attack, whichever occurs first.
Conversely, increasing speed above V imd requires a reduction in the angle of attack to maintain level flight. Additional thrust will be required to offset the increase in parasitic drag produced due to the additional speed that is required to enable the airfoil to generate the equivalent amount of lift at a lower angle of attack. At speeds above V imd , the aeroplane is in stable flight whereas at speeds below V imd , an aeroplane is in unstable flight.
The question of stability is illustrated by the effect of any encounter with air turbulence. This is referred to as being on the "back side of the drag curve". Certification of aircraft types includes the setting of M mo [1]. This is based upon setting a suitable margin from the Critical Mach Number M crit , at which airflow over a wing becomes transonic , that is, reaches the local speed of sound, and forms shock waves.
These shock waves induce Wave Drag and disturb previously smooth airflow leading to a loss of lift and. The margin between this upper limit and the prevailing TAS for a low speed stall, which increases as altitude increases and air density decreases, narrows with an increase in altitude resulting in a flight regime often referred to as Coffin Corner.
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