A PLT RPTS THAT AT CERTAIN APCH ANGLES AND DISTANCES THE RWY AND TXWY SIGNS APPEAR TO CREATE THE ILLUSION THAT THERE IS A VASI ON RWY 36 AT DCA. THERE IS NO VASI ON THIS RWY.

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THIS RPT IS TO BE A 'HEADS UP' ON A POTENTIALLY DANGEROUS SIT. ALTHOUGH RWY 36 AT DCA HAS NO VASI THE RWY AND TXWY MARKINGS ON THE L SIDE APCH END OF RWY 36 COULD EASILY BE MISTAKEN FOR A VASI. ON THE L SIDE OF RWY 36'S APCH END OF THE RWY THERE IS A TXWY SIGN (YELLOW) INDICATING; I BELIEVE; TXWY J. APPROX 1000 FT FURTHER DOWN ON THE L SIDE IS A (RED) RWY SIGN INDICATING RWY 15. WHEN ON FINAL THESE APPEAR TO BE A VASI SYS AND WILL ALWAYS INDICATE RED OVER WHITE; SHOULD THEY BE MISTAKEN AS SUCH. TO ILLUSTRATE THIS POINT; I MENTIONED THAT WE WERE SLIGHTLY HIGH ON THE ILS GLIDE PATH; BUT APPEARED TO BE RIGHT ON WITH REGARDS TO THE VASI. FOR A MOMENT THE 2 OTHER CREWMEMBERS AGREED. IT WASN'T UNTIL I MENTIONED THAT THERE WAS NO VASI THAT THEY REALIZED IT. I AM SURE THEY WOULD HAVE CAUGHT THAT FACT HAD I GIVEN THEM TIME. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR WAS FLYING A B727-200 INTO DCA WHEN HE FIRST NOTICED THE APPARENT VASI. HE RECHKED HIS APCH DATA AND NOTED THAT THERE WAS NO VASI SHOWN ON RWY 36; HOWEVER; AT CERTAIN APCH ANGLES AND DISTANCES THE TXWY AND RWY SIGNS WOULD APPEAR TO CREATE A VASI-TYPE DISPLAY. REF TO THE GS WOULD SHOW THAT ACTUALLY FOLLOWING THIS VASI WOULD PUT THE ACFT BELOW THE ACTUAL GS.