Question: I recently flew from Rome to Philadelphia on a 767.
I noticed on takeoff that the flaps were never extended. The winds
were light. I cannot remember the last time I flew when the pilot did
not extend the flaps to a small degree on takeoff. Is this normal?
-- submitted by reader David in Tampa
Answer: A 767 extends the slats on the front of the wing for all takeoffs. Some models of the 767-200 barely, if at all, move the trailing edge for a "Flaps 1" takeoff. That may have been what you experienced.
Q: I was recently flying from London to San Francisco on United. Somewhere over the Atlantic/Canada we heard a very strange loud noise; I surmised that it was the flaps being put up, as if to slow the aircraft down. Is this possible? If not, why else would the flaps be up mid-flight, and/or a loud noise coming from the wings/engine?
-- Michelle, San Francisco
A: There is a maximum altitude when the flaps can be extended -- in many airplanes it is 20,000 feet -- making it unlikely that it was the flaps moving. Flaps are located on the trailing edge (back) of the wing.
If you saw panels on the top of the wing extend and heard a buffeting noise, it could have been the flight spoilers being extended.
Q: Why do spoilers sometime deploy while at cruise altitude?
-- Don Bach, Madison, Wis.
A: Usually the flight spoilers are extended to increase the rate of descent. Because jets are so aerodynamically designed, they do not descend rapidly. If Air Traffic Control gives the flight an altitude restriction (e.g. cross a point at a specific altitude), it may be necessary to increase the descent rate. This is done by extending the flight spoilers, which adds drag and decreases the lift produced by the wing. Occasionally, as perhaps in the case above, it is also necessary to use flight spoilers to decrease the airspeed.
MORE: Read previous columns
John Cox is a retired airline captain with U.S. Airways and runs his own aviation safety consulting company, Safety Operating Systems.
-- submitted by reader David in Tampa
Answer: A 767 extends the slats on the front of the wing for all takeoffs. Some models of the 767-200 barely, if at all, move the trailing edge for a "Flaps 1" takeoff. That may have been what you experienced.
Q: I was recently flying from London to San Francisco on United. Somewhere over the Atlantic/Canada we heard a very strange loud noise; I surmised that it was the flaps being put up, as if to slow the aircraft down. Is this possible? If not, why else would the flaps be up mid-flight, and/or a loud noise coming from the wings/engine?
-- Michelle, San Francisco
A: There is a maximum altitude when the flaps can be extended -- in many airplanes it is 20,000 feet -- making it unlikely that it was the flaps moving. Flaps are located on the trailing edge (back) of the wing.
If you saw panels on the top of the wing extend and heard a buffeting noise, it could have been the flight spoilers being extended.
Q: Why do spoilers sometime deploy while at cruise altitude?
-- Don Bach, Madison, Wis.
A: Usually the flight spoilers are extended to increase the rate of descent. Because jets are so aerodynamically designed, they do not descend rapidly. If Air Traffic Control gives the flight an altitude restriction (e.g. cross a point at a specific altitude), it may be necessary to increase the descent rate. This is done by extending the flight spoilers, which adds drag and decreases the lift produced by the wing. Occasionally, as perhaps in the case above, it is also necessary to use flight spoilers to decrease the airspeed.
MORE: Read previous columns
John Cox is a retired airline captain with U.S. Airways and runs his own aviation safety consulting company, Safety Operating Systems.
No comments:
Post a Comment