What's the tail number of the airplane involved in the accident described as crashed?
CREATE TABLE "table1_229917_2" (
  "date_dd_mm_yyyy" text,
  "tail_number" text,
  "location" text,
  "fatalities" text,
  "brief_description" text
);
SELECT "tail_number" FROM "table1_229917_2" WHERE "brief_description"='Crashed';