PBI AIRSPACE USER EXPRESSED FRUSTRATION REGARDING ALT LIMITATIONS IMPOSED BY ZMA AND PBI LOA.

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AN UNSAFE SIT EXISTS IN THE AIRSPACE OF SOUTH FLORIDA THAT NEEDS SOME CONSIDERATION. I AM TOLD THAT AN 'LOA' EXISTS BTWN THE MIAMI ATC CTR AND PALM BEACH APCH CTL THAT REQUIRES ACFT DEPARTING FROM PBIA AIRSPACE TO THE E; OR RETURNING TO PBIA AIRSPACE FROM THE E TO STAY BELOW 6000 FT FOR 40 MI. JUST YESTERDAY; WHEN RETURNING TO PBIA FROM THE BAHAMAS; I WAS INSTRUCTED TO DSND TO 6000 FT BEFORE REACHING 42 MI TO THE E OF PBIA. NOT ONLY DOES THIS CAUSE EXTREME DISCOMFORT TO THE PAX BECAUSE IT CAUSES THE PLTS TO FLY THROUGH BUILDING CUMULOUS CLOUDS; BUT IT ALSO CAUSES AIRPLANES THAT ARE DESIGNED TO FLY AT HIGH ALTS TO BURN A SIGNIFICANT AMOUNT OF ADDITIONAL FUEL. IN ADDITION TO THESE 2 PROBS; THE RESTRS OF THESE LOA'S CREATE THE POSSIBILITY THAT THE PLT MAY INADVERTENTLY VIOLATE ONE OR MORE OF THE FOLLOWING FARS: 91.13; 91.103; 91.119; 91.123; 91.151; AND 91.167. I AM SURE THAT THE SUPVRS OF THE ZMA WILL SAY THAT THESE LOA'S ARE NECESSARY IN ORDER TO PROVIDE A SAFE ENVIRONMENT TO THE ACFT ARRIVING FROM THE NORTHEASTERN US; HOWEVER; IT IS CREATING AN UNSAFE ENVIRONMENT FOR THOSE OF US WHO ARE DEPARTING FROM AND RETURNING TO THESE SAME SOUTH FLORIDA ARPTS. THERE MUST BE A BETTER WAY!