Re: landing flaps

From:         spanman@primenet.com
Organization: Primenet
Date:         03 Sep 95 22:53:02 
References:   1 2 3
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arch6@inlink.com (Archibald McKinlay) wrote:

>....the flaps do usually have a higher design deployment speed......
>

This has not been my experience piloting Boeing 757 (currently) and
737 (previously) aircraft.

In the 757,  for example,  the maximum indicated airspeed for
extending flaps (or maneuvering with flaps extended) is 240 knots.
Landing gear can be extended at up to 270 knots.

In the 737,  the corresponding flaps limit speed is 230 knots.  Gear
can be extended at 270 knots, and the aircraft can be manuevered at up
to 320 knots once gear extension is complete.

It is routine practice to decelerate gradually and maneuver with flaps
extended prior to extending landing gear.  However, I would hesitate
to call this "normal" as it is equally "normal"  to extend gear first
under certain circumstances.

The  landing gear make very effective spoilers/speed brakes, and when
kept high or fast on approach by ATC, early gear extension is often
the best way to simultaneously descend on (or down to the) glide slope
and decelerate through the flap extension speeds.

>This type of ad hoc checklist change has also resulted in gear up
>approaches and some gear up passes.....

It's important to realize that Boeing's landing checklists do not
specify a sequence for flaps and gear extension; the checklists are
simply used to verify, prior to touchdown, that gear and flaps are
indeed positioned for landing.  In as much as Boeing's training
literature discusses sequence, it acknowleges that "operational
factors and/or terminal area procedures may....require adjustments to
meet the new requirements."

---
Don Steinman
Capt., B757
America West Airlines
spanman@primenet.com