The technique of the flute family is probably the highest and most refined of all the woodwinds. The bandestrator is thereby free to write nearly anything within the standard range of the instrument.
The only limitations are the bottom third of the instrument. With the exception of the combination of the low C to low D, all combinations of notes E-flat and lower require the sliding of the little finger. The D-flat to E-flat trill is the only impossible trill on the entire instrument.
For the entire flute family, the written low C is the standard bottom note. There are a few exceptions to this rule:
1. First, all Piccolos only descend to the low D. There are no exceptions.
2. The G Treble may or may not stop at the D, but this depends on the maker.
3. The C Flute itself is often equipped with a B-foot that allows the production of the lowest B natural. You should be fairly safe in the writing of this note as all professionals and most amateurs possess this extension.
4. The low B may or may not be present in the larger flutes. It is never present on the Alto and very rare on the Tenor. Consult with your players before using this note.
The upper written range for all flutes is given as the C three octaves above middle C, but again there are some exceptions. The top B and C on the Piccolo are extremely difficult to produce (owing surprisingly in part to the lack of the Low C) and can only be produced in forte. Advanced technique on the C Flute has pushed the range upwards to around an F, but in practicality, only the D above the high C should be used. The larger flutes are best kept out of their upper register (though the Alto has full use of all three octaves) and these notes are suspect and uncharacteristic of the instruments.
All flutes, from Piccolo to Contrabass, have the same sound signature. That is, their sound is soft in the bottom of the register and gradually gets louder as the pitch ascends. The softest sound in the flute family is a Contrabass on its lowest C (or B), while the absolute loudest sound is a Piccolo on its highest C.
By the way, the modern flute family, with all its new members, is the only family of winds that can cover virtually the entire range of the Piano (minus the low B-flat and A of the Piano).
One curious aspect of flute technique is that, as flutists are able to master the technique of their instrument fairly quickly (compared to most of the other woodwinds), many flutists venture out into performing works with extended techniques. These include quarter-tones, multiphonics, beat-boxing, glissandi, breathy sub-tones, and many more. Most of these techniques are used primarily in flute solos, and only rarely do they make their way into ensemble music.
When in doubt, ask a competent flutist.