Hello

Hmmmmm..... When your sustaining notes especially at the end of pieces how can you prevent the note from getting flat?? It sounds horrible

THANX

You need to direct your air upward more, and be sure to support through the end of the phrase. Don't let the air pressure drop, or your pitch will too. This probably is an especially big problem if you're decrescendoing at the end, so do some Trevor Wye long tones (slurring chromatically between two pitches) where you work specifically on decrescendoing without losing pitch.

Well one thing it could be is the weather is changing so your flute changes shape, by only a little but just so you become ether flat or sharp. if you have a tunner use it and ether pull out on your head joint or push in if this is the problem.
Another thing is the cork in the head joint could be getting old and warn out. Yes there is a cork, if you mess with the screw on the top it drys out, if so go to a repaire shop.

Moving the head in and out really isn't the best way to tune. You should do that with your air, as pushing in does not make all notes go equally sharp and pulling out does not make them all go equally flat. There's one position for the head where the scale is at it's best (the most notes are the most in tune). You should try to get the head into that position, and then make any necessary adjustments with your air/embouchure. Temperature can make a flute play slightly differently depending on whether it's cold or hot, but these changes are generally manageable unless it's extremely hot or cold. I've played piccolo (a metal one) in 27 degree whether here in CO, and even that didn't mess with my pitch all that much. Playing with the crown or adjusting the cork's position will not cause it to dry out any faster than it would normally. If you move the cork constantly (which you shouldn't be doing anyway), I suppose a certain amount of wear would be expected, and you might need the cork replaced sooner. Anyway, a leaky cork doesn't affect pitch as much as it does tone. I played on my Yamaha this summer with a cork in it that could be pulled about half way out of the tube, crownside, and while the tone and response weren't great, the pitch was just about where it usually is. However, if you have reason to believe the cork is dry or not sealing for any other reason, it's a good idea to have it replaced. It's fast, cheap, and can make a big difference to the way the flute plays.