Reamed out by Approach

If you hear a call for "Brsst 511" or "Bravo 511" and your tail
number ends in "511" you can safely assume it's for you.

that's a good assumption but don't assume, you should ask. On Norcal
appch over Hayward Airport, I was cleared to 4000. I read it back
and heard nothing. We then heard a HP 737 inbound to OAK cleared
to 4000. I said to my CFII if he could see the jet as I was under
the hood. He then asked and we were not cleared but a very similarly
sounded call sign was. No separation issues but if it were IMC,
it could have created a very dangerous area as we were flying
in the area of 3 cless C, a class B and 4 class D airports. Always
ask and don't assume.


If there are
two aircraft operating with the same or similar abreviated callsigns,
the controller is supposed to advise both aircraft and use the full
callsign for each aircraft.

'supposed to' but not required.

Gerald

G. Sylvester wrote:
If there are
two aircraft operating with the same or similar abreviated
callsigns,
the controller is supposed to advise both aircraft and use the full
callsign for each aircraft.

'supposed to' but not required.

Yes it is required. From the ATC handbook, Order 7110.65P :

2-4-9. ABBREVIATED TRANSMISSIONS

Transmissions may be abbreviated as follows:

a. Use the identification prefix and the last 3 digits or letters of
the aircraft identification after communications have been established.
Do not abbreviate similar sounding aircraft identifications or the
identification of an air carrier or other civil aircraft having an FAA
authorized call sign.


AND...

2-4-15. EMPHASIS FOR CLARITY

Emphasize appropriate digits, letters, or similar sounding words to aid
in distinguishing between similar sounding aircraft identifications.
Additionally:

a. Notify each pilot concerned when communicating with aircraft having
similar sounding identifications.

EXAMPLE-
"United Thirty-one United, Miami Center, U.S. Air Thirty-one is also on
this frequency, acknowledge."

John Galban=====N4BQ (PA28-180)