FAR 91.509 over water ops

[stlpilot]

Bit confused on this reg a student brought up to me today. Part A Reads:

(a) No person may take off an airplane for a flight over water more than 50 nautical miles from the nearest shore unless that airplane is equipped with a life preserver or an approved flotation means for each occupant of the airplane.

(b) Except as provided in paragraph (c) of this section, no person may take off an airplane for flight over water more than 30 minutes flying time or 100 nautical miles from the nearest shore, whichever is less, unless it has on board the following survival equipment:

So how do I know which one I have to comply with? 50 miles equiptment in part "A" or 30 minutes or 100 miles equiptment in part "B"?

I have a guess at this but it just jumbles in my brain today when I try to reason it, please give me your interpretations and how they apply or a good example might clear my head. Thanks

 

[midlifeflyer]

Bit confused on this reg a student brought up to me today. Part A Reads:

(a) No person may take off an airplane for a flight over water more than 50 nautical miles from the nearest shore unless that airplane is equipped with a life preserver or an approved flotation means for each occupant of the airplane.

Which means that if you're going more than 50 NM from shore you need life preservers

(b) Except as provided in paragraph (c) of this section, no person may take off an airplane for flight over water more than 30 minutes flying time or 100 nautical miles from the nearest shore, whichever is less, unless it has on board the following survival equipment:

Which means that you you're going more than 100 NM from shore or more than 30 minutes away from shore, you need a whole bunch of stuff.

So how do I know which one I have to comply with? 50 miles equipment in part "A" or 30 minutes or 100 miles equiptment in part "B"?

I have a guess at this but it just jumbles in my brain today when I try to reason it, please give me your interpretations and how they apply or a good example might clear my head. Thanks

I don't see the conflict. Don't look at them in the abstract. You look at the mission and decide whether one or the other applies. For example,

35 NM from shore in wind conditions (or a really slow airplane) that means that you couldn't get back within 30 minutes: (b) applies.

You =do= realize this only applies to Large and Turbine-Powered Multiengine Airplanes and Fractional Ownership Program Aircraft?