A Qantas A380 lands at Sydney International Airport on Sept. 13, 2016.(Photo: Rob Griffith, AP)
Question: Can a larger aircraft land on a shorter than recommended runway in an emergency? What tactics would a pilot use — slower approach speed, maximum reverse thrust, brakes to the firewall, etc. — to execute this?
— Steve Pontious, Beaumont, Texas
Answer: Yes, it can be done.
Every airplane has a required runway length due to the physics of decelerating. It is much shorter than many people realize. Large airplanes have operated into short airports. The Boeing 727 was a very good short field airplane due to its remarkable wing.
When landing on very short runways, the pilots will very carefully control the speed, touch down on the touchdown point and use all of the deceleration devices (brakes, spoilers and reverse thrust).
Q: What is the position of flaps for takeoff and landing?
— Tom, Scottsdale, Ariz.
A: It varies by the airplane type, weight, airport elevation, temperature, runway length and climb requirements.
Short runways usually require more flap extension to get airborne in the minimum amount of runway. Landing is the same, so as to touch down at the minimum speed and stop quickly. The ability to climb is decreased due to the extra drag of the flaps.
On longer runways or higher elevations, less flap is used so the climb performance is maximized.
Every takeoff and landing is calculated with multiple flap setting to determine the best one for that particular day.
Q: I was recently on a flight into SNA (John Wayne Orange County Airport) that had to divert to LAX. Per the captain, on approach to SNA, one flap was stuck in an incorrect position, so the landing was aborted. We landed at LAX on a longer runway without incident. I was wondering what issues pilots face when the flaps are stuck in an incorrect position during landing. Also, if an emergency is declared, does the captain take control of the aircraft, or does the first officer continue to fly?
— Michael, Calif.
A: I can understand the decision to divert to LAX with a flap asymmetry problem. Airplanes monitor and compare flap position; if there is a significant difference between flaps, a protection system stops the movement before it causes controllability problems. In the cases where I have had asymmetric flaps, the airplane was easily controllable but we did have to counter the difference in lift caused by the flap difference. The correction was to hold opposite roll control during the approach.
It is up to the captain if s/he wants to fly the airplane in an emergency or let the F/O fly it. This judgment is based on the type of emergency, experience of the F/O and conditions.
Q: Why does the Airbus A380 have thrust reversers only on the inboard engines?
— Cliff Clement, Oklahoma City
A: The outboard engines sit so far out that there was concern about causing damage to the airport surfaces near the runway. The wingspan of an A380 can be greater than the width of the runway.
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